RT 244 -12 Wk 14Digital Artifacts amp Imaging ERRORS

The advantages of CR are its large dynamic range digital format portability and post-processing capability

But not PERFECT ndashImaging Errors can still occur

See NOTES at bottom of slides for additional information

Some information obtained from AR Online raquo Current Issue raquo Artifacts and misadventures in digital radiography

By Charles E Willis PhD DABR Stephen K Thompson MS DABR S Jeff Shepard MS DABRVolume 33 Number 1 January 2004 1

Artifacts

bull Any irregularity on an image that is not caused by proper shadowing of tissue by the primary x-ray beam

bull Are undesirable optical densities or blemishes on a radiograph

bull Can be very interesting at times You become the detective what caused that

2

bull CR artifacts require special attention bull This is due to the fact that CR artifacts may be

produced from various components of the CR system itself

bull Artifacts may also be generated by the users who are not aware of the proper imaging techniques or selection of appropriate image processing protocols

bull Since CR is also very sensitive to scattered radiation it is vital that anti-scattered grids be used as in conventional radiography

bull Radiographers should be concerned since these may generate unwanted artifacts that could not be corrected by any image processing algorithm

3

Artifact Classification Review of FilmScreen

4

Artifact Classification Digital ndash CR amp DR

5

OPTIMIZATION OF CR IMAGES

Quality of CR imagesbullTechnologists are the key personsbull delivering good quality radiographsbulldose given to the patients bullCR images can NOT always be adjusted after exposing bullCRITICAL to CRDR Imaging isTechnique Positioning Collimation

6

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

bull CR artifacts require special attention bull This is due to the fact that CR artifacts may be

produced from various components of the CR system itself

bull Artifacts may also be generated by the users who are not aware of the proper imaging techniques or selection of appropriate image processing protocols

bull Since CR is also very sensitive to scattered radiation it is vital that anti-scattered grids be used as in conventional radiography

bull Radiographers should be concerned since these may generate unwanted artifacts that could not be corrected by any image processing algorithm

3

Artifact Classification Review of FilmScreen

4

Artifact Classification Digital ndash CR amp DR

5

OPTIMIZATION OF CR IMAGES

Quality of CR imagesbullTechnologists are the key personsbull delivering good quality radiographsbulldose given to the patients bullCR images can NOT always be adjusted after exposing bullCRITICAL to CRDR Imaging isTechnique Positioning Collimation

6

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Artifact Classification Review of FilmScreen

4

Artifact Classification Digital ndash CR amp DR

5

OPTIMIZATION OF CR IMAGES

Quality of CR imagesbullTechnologists are the key personsbull delivering good quality radiographsbulldose given to the patients bullCR images can NOT always be adjusted after exposing bullCRITICAL to CRDR Imaging isTechnique Positioning Collimation

6

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Artifact Classification Digital ndash CR amp DR

5

OPTIMIZATION OF CR IMAGES

Quality of CR imagesbullTechnologists are the key personsbull delivering good quality radiographsbulldose given to the patients bullCR images can NOT always be adjusted after exposing bullCRITICAL to CRDR Imaging isTechnique Positioning Collimation

6

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

OPTIMIZATION OF CR IMAGES

Quality of CR imagesbullTechnologists are the key personsbull delivering good quality radiographsbulldose given to the patients bullCR images can NOT always be adjusted after exposing bullCRITICAL to CRDR Imaging isTechnique Positioning Collimation

6

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Optimization of a CR image quality may be achieved by optimizing the following

factors

bull OBJECT ARTIFACTSndashPositioning and collimation

bull Exposure techniquesbull Image processing selectionbull Lifetime of the PSP

7

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

CR Artifactsbull Positioning errorsbull Collimation errorsbull Backscatter radiationbull LUT selectionhistogram

8

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Positioning of Part Collimationbull 2 or more two projections on one IR bull Is not a good practice with CR technique bull since double or multiple exposures on a single

PSP) can lead to a failure of the image processing software to detect the image boundary

bull Matching the positioning and collimation with the image processing parameters is also crucial

bull Image processing will eventually fail to process since the input information is totally different

9

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

10

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image

contrast

11

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

12

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Positioning Errors

13

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Collimation Errors 14

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

15

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Loss of contrast due to partitioning errors

16

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

17

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Alignment Error Same technique different centering and collimation

S 592S 664

18

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

19

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

2 on 24 X 301048697Same technique1048697Rescaling error

10486972 on 24 X 301048697Technique adjusted

20

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Single field per plate - better

21

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

What is the problem

22

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Placement of gonadal shields is no longer trivial

but may adversely affect image quality

23

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Software to compensate for metal in patient

24

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Same pt ndash what improved this image

25

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Acquiring good quality images

bull Regardless of the acquisition technology good radiographic images can be produced only when certain fundamental requirements are met

bull Appropriate radiographic technique must be used bull proper tube potential (kVp) bull beam current (mAs) bull source-to-image distance (SID) bull collimation bull alignment of the X-ray central ray bull and positioning of detector and subject for the specific

anatomic projection

26

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Exposure techniquesbull CR may be operated at a different film speed

and then optimizing the exposure technique accordingly

bull Existing CR has a speed similar to medium speed film-screen system (200 -400) while spatial resolution is still generally inferior

bull Proper selection of an image processing algorithm specific to each type of x-ray examination is thus important

bull The technical skills of radiographers definitely play a crucial role in determining the quality of the radiographic image

27

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Exposure factor ldquocreepbull related to the wide exposure latitude of DR bull noise in DR images exposed at one-fourth to one-

half of the appropriate level bull artifacts are generally not apparent until the

exposure exceeds 10 times the appropriate level bull Technologists avoid repeating an underexposed

study by routinely increasing the radiographic technique

bull Thus the potential for gross overexposure exists in DR Image optical density (OD) the usual indicator of proper exposure is arbitrary in DR

bull Managment of exposure factor in DR must rely on the value of a derived exposure indicator

28

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Errors in the selection of the anatomic projection can cause inappropriate processing

29

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Wrong Algorithm

30

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

OverUnder Exposedbull Even though a CR image may be adjusted to improve

the image visibility in the cases of over- or under-exposures it would still be impossible for an image processing to improve the visibility of clinical features that were not available in the raw image

31

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

32

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

33

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

34

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

the same image now shows acceptable image quality as a result of proper selection of image processing

35

bull Example of artifacts in CR an image with loss of contrast as a result of improper selection of image processing

bull

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

36

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

37

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)

38

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images

39

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Different exam parametersin different rooms

40

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Double exposure is a classic operator error

bull that constitutes approximately 2 of all rejected images

bull The consequence of double exposure can be either a single repeated examination when an inanimate object is involved (Figure 11) or two repeated examinations when two patients are involved (Figure 12)

bull In DR double exposures can also be caused by power interruptions and communications errors as well as by inadequate erasure secondary to overexposure or erasure mechanism failure

41

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Double exposure (Figure 11)

42

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Double exposure 12

43

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

44

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

8

45

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Edge Enhancementbull The secondary function of image processing is to

customize contrast in the region of interest bull This type of image processing includes modifying the

image to enhance the contrast and sharpness of some features while compromising the contrast and sharpness of others

bull as well as modifying the image to make it appear more like a conventional film

bull This secondary image processing is applied in a manner that is usually specific to the anatomic projection

46

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

standard image edge sharpening

47

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

bull Halo effect with Edge enhancement48

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

49

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Post Processing

bull An auxiliary purpose of image processing is to improve the usability of the digital image

bull This includes imprinting demographic overlays adding annotations applying borders and shadow masks flipping and rotating increasing magnification conjoining images for special examinations like scoliosis and modifying the sequence of views

bull This processing may require a separate QC workstation

50

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

51

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

IR Artifact - Digital

bull Pixel Failure = CR amp DR plates should last for thousands of exposures Interpolation can be used to fix defects in a small area

bull Ghosting artifacts = exposure to environmental radiation or incomplete erasure

52

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

background radiation

53

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Image Receptor Artifacts

bull Debris on image receptor in DR can be confused with foreign bodies

54

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Image Receptor Artifacts

Line caused from dirt collected in a CR Reader

55

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

imaging plate was not fully erased before the chest examination was performed

56

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Dirt on screens

57

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

9

58

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

59

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

60

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

61

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

62

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Lifetime of the PSPbull One of the major advantages of CR is that the

phosphor plate is reusable bull However there are a number of factors that may

affect the lifetime of an imaging plate bull The plates are subjected to normal wear and tear

from scratches scuffs cracks and contamination with dust and dirt which may interfere with the production of a good image

bull The establishment of a well-organized quality control program will play an important role in assessing the clinical quality of the imaging plate This may easily be carried out by artifact assessment and uniformity evaluation across the plate

63

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Software Artifacts

64

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Processing Errors

65

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Digital Radiography Image Sampling

bull Image sampling the plate is scanned and the imagersquos location and its orientation are determined The size of the signal is then determined and a value is placed on each pixel A histogram is generated from the image data

bull The raw data used to form the histogram are compared with a ldquonormalrdquo histogram of the same body part by the computer

66

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

The Nyquist Theorem

bull States that when sampling a signal (such as the conversion from an analog to a digital image) the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect

bull At least twice the number of pixels needed to form the image must be sampled If too few pixels are sampled the result will be a lack of resolution

67

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Aliasing amp Grid errors = Moireacute

bull Spatial frequency is greater than the Nyquist frequency a wraparound image is produced moireacute effect

bull Stationary Grids grid lines and the scanning laser are parallel moireacute effect

68

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Moireacute effect

69

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Software Artifacts

bull Image Compression ndash Used with teleradiology

Compression techniques ldquolosslessrdquo or ldquolossyrdquo

70

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Image Compression

bull Lossless compression image can be reconstructed to be exactly the same as the original image Compressed 10 or 50

bull Lossy compression image is compressed 1001 Used only when fine detail is not required Not useful for medical imaging

71

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Image Compression

72

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

bull Wider dynamic range means that technologists have to pay attention to exposure indicator values instead of brightness and contrast Without this attention patient dose will escalate If exposure indicator logs are available they need to be evaluated If they arent this will need to be done manually

73

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include

Misuses of image processing include

bull compensating for inappropriate radiographic technique bull compensating for poor calibration of acquisition and display

devices bull and surreptitious deletion of nondiagnostic imagesbull Image processing to recover nondiagnostic images to prevent

re-exposure should be a last resort not a routine activity bull Routine reprocessing indicates a problem with automatic

image processing or technical practice Access to image-processing software is essential to develop and maintain appropriate processing parameters

74

• RT 244 -12 Wk 14 Digital Artifacts amp Imaging ERRORS
• Artifacts
• PowerPoint Presentation
• Artifact Classification Review of FilmScreen
• Artifact Classification Digital ndash CR amp DR
• OPTIMIZATION OF CR IMAGES
• Optimization of a CR image quality may be achieved by optimizing the following factors
• CR Artifacts
• Positioning of Part Collimation
• Slide 10
• Errors in collimation can cause mistakes in detection of the boundary with a dramatic loss of image contrast
• Slide 12
• Slide 13
• Slide 14
• Slide 15
• Loss of contrast due to partitioning errors
• Slide 17
• Alignment Error Same technique different centering and collimation
• Slide 19
• Slide 20
• Single field per plate - better
• What is the problem
• Placement of gonadal shields is no longer trivial but may adversely affect image quality
• Software to compensate for metal in patient
• Same pt ndash what improved this image
• Acquiring good quality images
• Exposure techniques
• Exposure factor ldquocreep
• Errors in the selection of the anatomic projection can cause inappropriate processing
• Wrong Algorithm
• OverUnder Exposed
• Slide 32
• Slide 33
• Slide 34
• Slide 35
• Slide 36
• Slide 37
• Too many X-rays are a disservice to the patient and may also produce poor images (Figure 3)
• Whether from underexposure or misalignment of a scatter reduction grid too few X-rays produce noisy images
• Different exam parameters in different rooms
• Double exposure is a classic operator error
• Double exposure (Figure 11)
• Double exposure 12
• Slide 44
• 8
• Edge Enhancement
• Slide 47
• Slide 48
• Slide 49
• Post Processing
• Slide 51
• IR Artifact - Digital
• background radiation
• Image Receptor Artifacts
• Slide 55
• imaging plate was not fully erased before the chest examination was performed
• Dirt on screens
• 9
• Slide 59
• Slide 60
• Slide 61
• Slide 62
• Lifetime of the PSP
• Software Artifacts
• Processing Errors
• Digital Radiography Image Sampling
• The Nyquist Theorem
• Aliasing amp Grid errors = Moireacute
• Moireacute effect
• Slide 70
• Image Compression
• Slide 72
• Slide 73
• Misuses of image processing include