diagnostic x-ray imaging systems quality...
TRANSCRIPT
MINISTRY OF HEALTH AND SOCIAL SERVICES
Ministry of Health and Social ServicesP/ BAG 13198Ministerial BuildingHarvey StreetWindhoek 9000.Namibia
Tel: + 264 (61) 2032417Fax: 264 (61) 230 424
E-mail: [email protected]: aebofnamibia.org
NATIONAL RADIATION PROTECTION AUTHORITYCODE: DIAGNOSTIC X-RAY IMAGING SYSTEMS
QUALITY CONTROL
REPUBLIC OF NAMIBIANATIONAL RADIATION PROTECTION AUTHORITYCODE: DIAGNOSTIC X-RAY IMAGING SYSTEMS
QUALITY CONTROL
REPUBLIC OF NAMIBIANATIONAL RADIATION PROTECTION AUTHORITY
CODE: DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL
Table of Contents
1. Introduction.................................................................................................................................... 1
2. GENERAL REQUIREMENTS.............................................................................................................. 2
2. TABLE 1 INDIVIDUAL EQUIPMENT RECORD (IER).......................................................................... 3
3. Table 2: Quality control tests.......................................................................................................... 4
3.1 General tests.................................................................................................................................. 4
3.2 X-ray Tubes and Generators............................................................................................................ 4
3.3 Fluoroscopy Equipment.................................................................................................................. 6
3.4 Computed Tomography................................................................................................................... 7
3.5 Mammography Screen film........................................................................................................... 8
3.6 Mammography Digital.................................................................................................................... 11
3.7 Processor Monitoring..................................................................................................................... 14
3.8 Intensifying Screens and Darkroom................................................................................................ 14
3.9 Dental Radiography......................................................................................................................... 15
4. Table 3: HVL values......................................................................................................................... 16
5. REFERENCES.................................................................................................................................... 17
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL1
1. Introduction
X-ray technology has developed extensively over the years with remarkable improvement in the quality of imaging, mainly due to improved technological adaptations. We must remain vigilant of our role as health care provider and the principles of primary health care. In the framework of imaging technology we are endeavouring to provide quality health care services through diagnostic imagining techniques while we should also be mindful to keep the deleterious effect to a minimum. At the centre of this approach is the concept of optimisation which is to derive maximum benefit from the technology while also keeping the potential harm to the minimum possible, taking into account economy, and social factors. Therefore any dose to any patient must be the minimum possible without compromising to achieve the desire diagnostic information. There are two parameters that are necessary to be optimised in order to achieve this objective.
The operator must have the competency to use the equipment, positions the patient, select the most appropriate parameters, deliver the exposure and process the image in a most effective and efficient manner to ensure that the patient derives maximum benefit from the service. The operator must also be equipped to monitor and observe discrepancies that may arise if the equipment is not performing optimally. Therefore the authority considers an important aspect that operators have the educational qualifications, experiences and skills to perform diagnostic imaging and shall continue to develop the means to equip them in terms of optimisation of protection.
The second parameter is that of the equipment which must conform to international standards and provide the optimal output necessary to obtain the desired diagnostic information. This output is dependent on a number of parameters such as the ma, Mas, kv, etc. These parameters must remain within recommended tolerance performance to ensure that the output remains constant and optimal. It is for this reason that this document is issues to all stakeholders to ensure that at all times during operation, after installation and maintenance that the tolerance levels are achieved and maintained.
In the context of the above I wish to re-iterate that the purpose of protecting the patient is to ensure that the radiation exposure remains low as reasonably achievable without compromising of the beneficial diagnostic information of the investigation. It is particularly the stochastic effect that we have in mind when we emphasis this concept. The immediate benefit should not be at the expenses of causing other major health effects later in life and thereby placing an extra burden on our health care system.
I trust that this document shall serve the purpose, for which it was formulated, especially by the manufacturers, suppliers, maintenance engineers and other professional who have a direct influence in the operation of devices that are used for patient exposures.
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 2
2. GENERAL REQUIREMENTS
THE LICENCE HOLDER SHALL:
1. Display the product licence number of equipment.
2. Compile an Individual Equipment Record (IER) containing the information as listed in table1 (column 2)
a. IER is for example a ring binder containing all the information as prescribed in table 1 for each piece of
equipment.
3. Perform the prescribed Acceptance- and Quality Control (QC) tests listed in this document
4. Acquire the relevant quality control manuals or compile in-house written protocols, which describe each
test step by step to ensure that QC tests listed in this document are correctly performed.
5. Ensure that radiographers that perform routine tests listed in the document are competent to execute
the tests.
6. Ensure that the required acceptance tests are performed before the diagnostic x-ray equipment is
put into clinical service when: Acquired or substantially upgraded. Acceptance tests are the initial tests
performed directly after installation and before the equipment is being put into clinical service. Acceptance
tests have three purposes, namely:
a. To ensure that the unit meets stated specifications,
b. To establish baseline parameters for the future quality control program,
c. And To familiarize the customer with operation of the unit.
7. Ensure that all the quality control tests are performed at the prescribed frequencies as listed.
QC tests may be performed more frequently than specified, influenced by the age, stability, make, model,
etc., of the equipment.
8. Ensure that image display monitors and reporting monitors comply with the requirements in this
document.
9. Establish a program to ensure that the radiation dose administered to a patient for diagnostic purposes is
optimised.
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL3
2.1 TABLE 1 INDIVIDUAL EQUIPMENT RECORD (IER)
General Radiography Equipment
Proccessor & Hard copy
device
CR Reader
DDR System
Film Viewer
Reporting Monitor
Fluoroscopy Equipment
Computed Tomography Equipment
Mammography equipment
a) Unit-make, model and serial number
x x x x x x x
b) Generator-make, model and serial number
x x x x
c) Product license number, date of the latest license
x x x x
d) Date of installation
x x x x x x x x x
e) Operators manual- (indication that the operator’s manual is available and reference where it is kept
x x x x x x x
f) Results of acceptance tests
x x x x x x x x
g) Results of routine quality control tests
x x x x x x x x x
h) Date of tube replacement
x x x x
i) Details of repairs/maintenance and/or modifications
x x x x x x x x x
j) Details of the company that perform the test(s)
x x x x x x x x
• Please note: for new equipment acceptance tests is the responsibility of the company that installed the equipment.
The x in each cell for each category of equipment indicates which information must be available in the IER.
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 4
3.Table 2: Quality control testsPhysical parameter (required test)
Frequency Acceptance Standard
Responsible person
References
3.1 General tests
3.1.1 Safety of premises
On acceptance & and when the workload increase or technique factors change that may jeopardise premises safety
Controlled areas ≤ 5mSv/year, for uncontrolled areas ≤ 1mSv/year
NRPA inspectors
3.1.2 Indicators, mechanical and other safety checks & warm-up
On acceptance & Daily
Results must be documented at least once every 3 months
Radiographer/RSO
3.1.3 Gonad shields, lead rubber aprons and gloves
3 monthly Available and free from holes or cracks (Visual check and if suspect perform an x-ray test)
Radiographer/RSO
Ref 2, 12
2.1.4 Appropriate technique chart displayed at x-ray
6 monthly unit Available, applicable and compliant with ALARA principle
Radiographer/RSO
Ref 11
3.2 X-ray Tubes and Generators
3.2.1 Accuracy of the source (focal spot)-to-image distance (SID) indicators
On acceptance & 12 monthly
The difference between the indicated focus to film distance (FFD) and the actual FFD must be ≤ 2%
Medical physicist/ Qualified service provider
Ref 2, 12
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL5
3.2.2 Brightness of the light field, which defines the x-ray field
On acceptance & 12 monthly
Average illuminance must be ≥ 100 lux at 100 centimetres or at the maximum FFD, whichever is less
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.3 Alignment of the centre of the X-ray field and the centre of the bucky
On acceptance & 12 monthly
Deviation must be ≤ ±1 cm @1m
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.4 The X-ray field dimensions in the plane of the image receptor must correspond with those indicated by the beam-limiting device
On acceptance &12 monthly
Deviation must be ≤ ±1 cm @1m SID
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.5 Congruence between the X-ray field and light field
On acceptance & 12 monthly
For any one side deviation must be ≤ ±1 cm isalignment @1 m SID
Radiographer/RSO
Ref 2, 12
3.2.6 Radiation output: reproducibility
On acceptance & 12 monthly
Baseline ± 10% Medical physicist/ Qualified service provider
Ref 2, 12
3.2.7 The accuracy of the timer for different settings
On acceptance & 12 monthly
Manufacturers’ specifications for specific model or if not available ≤ 5 %
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.8 The accuracy of the kV for different settings
On acceptance & 12 monthly
Manufacturers’ specifications for specific model or if not available ≤ 5%
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.9 Beam quality( (half value layer (HVL)
On acceptance & and annually
Limiting values are shown in table 3
Medical physicist/ Qualified service provider
Ref 2, 12
3.2.10 Leakage radiation from the diagnostic source assembly (x-ray tube)
At acceptance and annually
< 1 mGy in 1 hour at 1 m from the focus
Medical physicist/ Qualified service provider
Ref 2, 12
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 6
3.3 Fluoroscopy Equipment (in addition to tests in no 3.2)3.3.1 Display monitor
set–up On acceptance & 12 monthly
All steps visible and black/white circles using the SMEPT pattern test
Medical physicist/ Qualified service provider
Ref 13
3.3.2 Minimum requirements for monitors
On acceptance & 12 monthly
Comply with manufacturers recommendation
Medical physicist/ Qualified service provider
Ref 13
3.3.3 Field limitation requirement X-Ray field/Image intensifier
On acceptance & 12 monthly
The ratio of the areas ≤ 1.15
Medical physicist/ Qualified service provider
Ref 13
3.3.4 Dose rate at entrance surface of phantom (Skin dose)
On acceptance & 12 monthly
≤ 50 mGy/min (entrance air kerma) and baseline ± 25% or manufacturers specification
Medical physicist/ Qualified service provider
Ref 13
3.3.5 Entrance exposure rate to image intensifier
On acceptance & 12 monthly
Baseline ± 25% of manufacturers specification
Medical physicist/ Qualified service provider
Ref 13
3.3.6 Dose rate reproducibility ( under automatic exposure control )
On acceptance & annually
manufacturers specification
Medical physicist/ Qualified service provider
Ref 13
3.3.7 Radiation warning light at entrance, excluding theatres
On acceptance & Daily
Must work when beam is activated
Radiographer
3.3.8 Check of Dose area product meter (DAP/KAP meter) or the device that provides a dose read-out during fluoroscopy (total dose)
On acceptance & 12 monthly
DAP/KAP meter or dose read out device according to manufacturer’s specifications
Medical physicist/ Service provider
Ref 4
3.3.9 Overall Image quality
On acceptance & 12 monthly
Manufacturer’s specifications for a specific model
Medical Physicist/ Service provider
Ref 13
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL7
3.4 Computed Tomography3.4.1 Image noise On acceptance
& 12 monthly Baseline ± 10% Inter –slice variation; Mean ± 10%
Medical Physicist/ Service Provider
Ref 12
3.4.2 CT number values
On acceptance & 12 monthly
Water baseline ± 5 HU Other materials: baseline ± 10HU
Medical Physicist/ Service Provider
Ref 12
3.4.3 CT number uniformity
On acceptance & 12 monthly
Head phantom: ≤±10HU Body phantom: ≤±20HU
Medical Physicist/ Service Provider
Ref 12
3.4.4 Laser Alignment On acceptance & 12 monthly
Allowed misalignment ± 1mm
Radiographer/RSO Ref 12
3.4.5 Couch travel On acceptance & 12 monthly
Allowed misalignment ± 1mm
Radiographer/RSO Ref 12
3.4.6 High contrast spatial resolution
On acceptance & 12 monthly
Baseline ±20% Medical Physicist/ Service Provider
Ref 12
3.4.7 Computed tomography dose index (CTDI)
On acceptance & 12 monthly
Baseline ±15% Medical Physicist/ Service Provider
Ref 12
3.4.8 Image slice thickness
On acceptance & 12 monthly
Baseline ±20% or ± 1mm, whichever is greater
Medical Physicist/ Service Provider
Ref 12
3.4.9 CTDIvol for single slice or rotation
On acceptance & 3 yearly
≤ Reference dose - table 3 of reference 1.2
Medical Physicist/ Service Provider
Ref 12
3.4.10 CT warm up test Daily manufacturers specification
Radiographer Ref 12
3.4.11 Indicators, radiation warning light at entrance, mechanical and other safety checks
On acceptance & Daily
Must work properly Radiographer/RSO Ref 12
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 8
3.5 Mammography Screen film3.5.1 Image quality
evaluation (phantom images)
1 monthly or weekly
At a minimum, the 4 largest fibers, the 3 largest speck groups, and the 3 largest masses must be visible.
The background optical density must be at least 1.4 and the density difference should be at least 0.4 for a 4-mm thick acrylic disk.
Medical Physicist/ Radiographer
Ref 5, 9
3.5.2 Compression (force and alignment)
On acceptance & annually
manufacturers specification Radiographer/ RSO
Ref 5
3.5.3 Repeat and reject analysis
3 monthly May not increase with more than 2% from the previous determined rate and total rate shall not exceed 5%
Radiographer/RSO
Ref 5
3.5.4 Appropriate exposure technique chart (automatic and manual exposures) displayed near the control panel of the unit
6 monthly Available and applicable Radiographer/RSO
Ref 11
3.5.5 Analysis of fixer retention in film
6 monthly The residual fixer retention shall be ≤ 5 micrograms per square cm
Radiographer/RSO
Ref 5, 9
3.5.6 Assessment of locks, detents, angulations indicators, and mechanical support devices for X-ray tube and image receptor holder assembly
On acceptance & 12 monthly
Must function properly Medical Physicist/ Service Provider
Ref 5, 9
3.5.7 Collimation assessment: Deviation between X-ray field and light field
On acceptance & 12 monthly
The sum of left plus right edge deviations or anterior plus chest edge deviations must be ≤ 2% of SID
Medical Physicist/ Service Provider
Ref 5, 9
3.5.8 Collimation assessment: Deviation between X-ray field and edges of the image receptor
On acceptance & 12 monthly
The X-ray field may not exceed the image receptor at any side by more than 2% of SID and the X-ray field may not fall within the image receptor on the chest wall side
Medical Physicist/ Service Provider
Ref 5, 9
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL9
3.5.9 Collimation assessment: Alignment of chest-wall edges of compression paddle and film
On acceptance & 12 monthly
The chest-wall edge of the compression paddle may not fall within the image receptor or project beyond the chest-wall edge of the image receptor by more than 1% of SID
Medical Physicist/ Service Provider
Ref 5, 9
3.5.10 Evaluation of system resolution
On acceptance & 12 monthly
The resolution with the bars parallel to the anode-cathode axis must be ≥ 13 line–pairs/mm or with the bars perpendicular to the anode-cathode axis must be ≥ 11 line–pairs/mm
Medical Physicist/ Service Provider
Ref 5, 9
3.5.11
Automatic exposure control (AEC) : system performance
On acceptance & 12 monthly
Equipment sold prior to 01/01/2003:
The AEC system must maintain the film optical density within ±0.3 of the mean when the thickness of the phantom is varied over 2-6 cm and the kVp is varied over the range of those used clinically for these thickness. If this requirement cannot be met, a technique chart shall be developed showing appropriate techniques (kVp and density control settings) for different breast thickness and compositions that must be used so that optical densities within±0.3 of the average can be produced under photo timed conditions.
Equipment sold after 01/01/2003: The AEC system must maintain the film optical density within ±0.15 of the mean when the thickness of the phantom is varied over 2-6 cm and the kVp is varied over the range of those used clinically for these thickness.
Medical Physicist/ Service Provider
Ref 5, 9
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 10
3.5.12 Automatic exposure control (AEC) system performance: Density control
On acceptance & 12 monthly
Each step (density setting) shall result in a 12-15% change in mAs, or approximately a 0.15 change in film optical density
Medical Physicist/ Service Provider
Ref 5, 9
3.5.13 AEC reproducibility On acceptance & 12 monthly
The coefficient of variation for R (exposure) or mAs must be ≤ 0.05
Medical Physicist/ Service Provider
Ref 5, 9
3.5.14 Artefact evaluation On acceptance & 12 monthly
No significant artefacts must be visible
Radiographer/RSO
Ref 5, 9
3.5.15 kVp accuracy and reproducibility
On acceptance & 12 monthly
The mean kVp may not differ from the nominal kVp (set value) with more than ±5%, or the coefficient of variation may not exceed 0.02
Medical Physicist/ Service Provider
Ref 5, 9
3.5.16 Beam quality (HVL) measurement
On acceptance & 12 monthly
The measured HVL must be ≥ kVp/100 (mm Al) (Please note 0.03 must be added when filtration is performed with compression paddle
Medical Physicist/ Service Provider
Ref 5, 9
3.5.17 Average glandular dose
On acceptance & 12 monthly
The dose must be ≤ 300 mRad (3 mGy) for 4.2 cm effective breast thickness
Medical Physicist/ NRPA
Ref 5, 9
3.5.18 View box luminance, room illuminance and masking
On acceptance & 12 monthly
Luminance of the view box shall be ≥ 3000 cd/m2 and iluminance of the room shall be ≤ 50 lux Viewboxes must be masked to the exposed area of the film
Radiographer/RSO
Ref 5, 9
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL11
3.6 Mammography Digital 3.6.1 Repeat and
reject analysis 3 monthly May not increase with more
than 2% from the previous determined rate and total rate shall not exceed 5%
Radiographer/RSO Ref 5
3.6.2 AEC device: Long term reproducibility
On acceptance & 12 monthly
Variation of SNR in the reference ROI and dose < ± 10%.
Medical Physicist/ Service Provider
Ref 5
3.6.3 Image receptor homogeneity
On acceptance & 12 monthly Weekly ≤ ± 10%
Variation in mean pixel value < ± 15% (on images); Maximum deviation in SNR < ± 15% of mean SNR (on images); Maximum variation of the mean SNR between weekly images ≤± 10% (between images); Entrance surface air kerma OR tube loading (mAs) between monthly images
Radiographer/RSO Ref 5
3.6.4 Image quality evaluation (phantom images )
12 monthly At a minimum, the 5 largest fibers, the 4 largest speck groups, and the 4 largest masses must be visible. The background optical density must be at least 1.4 for hard copy.
Medical Physicist/ Radiographer
Ref 5
3.6.5 Assessment of locks, detents, angulations indicators, and mechanical support devices for X-ray tube and image receptor holder assembly
On acceptance & 12 monthly
Items that are hazardous, inoperative or fail to operate correctly should be repaired by the appropriate equipment manufacturer.
Medical Physicist/ Service Provider
Ref 5
3.6.6 X-ray source: Source-to-image distance – Only if adjustable
On acceptance & 12 monthly
Manufacturers specification, typical 600-650 mm
Medical Physicist/ Service Provider
Ref 5
3.6.7 X-ray source: Alignment of X-ray field/image receptor
On acceptance & 12 monthly
All sides: X-rays must cover the film by no more than 5 mm outside the film. On chest wall edge: distance between film edge and edge of the bucky must be ≤ 5 mm.
Medical Physicist/ Service Provider
Ref 5
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 12
3.6.8 X-ray source: Radiation leakage
On acceptance and after intervention on the tube housing.
≤ 1 mGy in 1 hour at 1 m from the focus
Medical Physicist/ Service Provider
Ref 5
3.6.9 X-ray source: Tube output
On acceptance & 12 monthly
>30 µGy/mAs at 1 metre and > 70% of value at acceptance
Medical Physicist/ Service Provider
Ref 5
3.6.10 Tube voltage reproducibility and accuracy
On acceptance & 12 monthly
Accuracy for the range of clinically used tube voltages: < ± 1 kV
Medical Physicist/ Service Provider
Ref 5
3.6.11 Half Value Layer (HVL)
On acceptance and after intervention on the tube
For 28 kV Mo/Mo the HVL must be over 0.30 mm Al equivalent
Medical Physicist/ Service Provider
Ref 5
3.6.12 AEC-system: Optical density control setting: central value and difference per step (if applicable)
On acceptance & 12 monthly
5 - 15% increase in exposure per step
Medical Physicist/ Service Provider
Ref 5
3.6.13 AEC-system: Short term reproducibility
On acceptance & 12 monthly
< ± 5% Medical Physicist/ Service Provider
Ref 5
3.6.14 AEC-system: Object thickness and tube voltage compensation
On acceptance & 12 monthly
Thickness indicator < ± 0.5 cm and density < ± 0.15 OD.
Medical Physicist/ Service Provider
Ref 5
3.6.15 Compression force
On acceptance & 12 monthly
130 - 200 N (13-20 kg) maintained unchanged for at least 1 minute and indicated compression force should be within ± 20 N of the measured value
Radiographer/RSO Ref 5, 12
3.6.16 Compression plate alignment
On acceptance & 12 monthly
≤ 5 mm Radiographer/RSO Ref 5, 12
3.6.17 Grid system factor (if present)
On acceptance, or if faulty
Manufacturer’s specification, typical value < 3.
Medical Physicist/ Service Provider
Ref 5
3.6.18 Grid imaging On acceptance & 12 monthly
No significant non uniformity Medical Physicist/ Service Provider
Ref 5
3.6.19 Image receptor response function
On acceptance & 12 monthly
R2 > 0.99, results at acceptance are used as reference
Medical Physicist/ Service Provider
Ref 5
3.6.20 Image receptor Noise evaluation
On acceptance & 12 monthly
Results at acceptance are used as reference
Medical Physicist/ Service Provider
Ref 5
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL13
3.6.21 Missed tissue at chest wall side
On acceptance Width of missed tissue at chest wall side ≤ 5 mm
Medical Physicist/ Service Provider
Ref 5
3.6.22 Image receptor homogeneity and Image receptor detector element failure (DR systems)
On acceptance & 12 monthly
Variation in mean pixel value < ± 15% (on images); Maximum deviation in SNR < ± 15% of mean SNR (on images); Maximum variation of the mean SNR between weekly images ≤± 10% (between images); Entrance surface air kerma OR tube loading (mAs) between annual images ≤ ± 10% .Limits of the manufacturer
Medical Physicist/ Service Provider
Ref 5
3.6.23 Inter plate sensitivity variations (CR systems)
On acceptance & 12 monthly
SNR variation ≤ ± 15%. Variation in entrance surface air kerma OR tube loading (mAs)≤± 10%.
Medical Physicist/ Service Provider
Ref 5
3.6.24 Influence of other sources of radiation (CR)
On acceptance The coins should not be visible.
Medical Physicist/ Service Provider
Ref 5
3.6.25 Fading of latent image (CR)
On acceptance Results at acceptance are used as reference.
Ref 5
3.6.26 Dosimetry On acceptance & 12 monthly
< 2.5 mGy for 4.5 cm PMMA Medical Physicist/ Service Provider
Ref 5, 12
3.6.27 Threshold contrast visibility (use contrast line pair test)
On acceptance & 12 monthly
manufacturers specification Medical Physicist/ Service Provider
Ref 5
3.6.28 Exposure time On acceptance & 12 monthly
manufacturers specification Medical Physicist/ Service Provider
Ref 5
3.6.29 Geometric distortion and artefact evaluation
On acceptance & 12 monthly
No disturbing artefacts, no visible distortion.
Medical Physicist/ Service Provider
Ref 5
3.6.30 Ghost image/erasure thoroughness
On acceptance & 12 monthly
“Ghost image”-factor < 0.3 Medical Physicist/ Service Provider
Ref 5
3.6.31 Monitors : Ambient light
On acceptance & 12 monthly
< 10 lux or manufacturers specification
Medical Physicist/ Service Provider
Ref 5
3.6.32 Monitors: Resolution
On acceptance & 12 monthly
All line patterns should be discernible.
Medical Physicist/ service Provider
Ref 5
3.6.33 Monitors: Luminance range: Maximum to minimum luminance ratio
On acceptance & 12 monthly
Primary display devices ≥ 250 Secondary display devices ≥ 100; Displays belonging to one displaying station should not exceed 5% of the lowest
Medical Physicist/ Service Provider
Ref 5
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 14
3.6.34 Monitors: Greyscale Display Function
On acceptance & 12 monthly
<± 10% of the GSDF for primary class displays and <± 20% of the GSDF for secondary class displays (default test pattern to be used)
Medical Physicist/ Service Provider
Ref 5
3.6.35 Monitors: Luminance uniformity
On acceptance & 12 monthly
Maximum luminance deviation of a display device should be less than 30% for CRT displays and LCD displays ((Lmax-Lmin)/Lcentre < 0.3).
Medical Physicist/ Service Provider
Ref 5
3.6.37 Monitors: Density uniformity
On acceptance & 12 monthly
Maximum optical density deviation should be less than 10% ((Dmax -Dmin)/Dcentre < 0.1)
SMEPT pattern
Medical Physicist/ Service Provider
Ref 5
3.7 Processor MonitoringTests must be performed before diagnostic films are processed. All measurements must be plotted on graph paper 3.7.1 Processing
temperature Daily Baseline ±1ºC Radiographer Ref 12
3.7.2 Base + Fog (B+F)
Daily Variance ≤ +0.03 OD. Maximum OD < 0.3
Radiographer Ref 12
3.7.3 Mid-density (MD) step (speed index)
Daily Variance ≤ ± 0.15 OD
Radiographer Ref 12
3.7.4 Density difference (DD) (contrast index)
Daily Variance ≤ ± 0.15 OD
Radiographer Ref 12
3.8 Intensifying Screens and Darkroom
3.8.1 Cleanliness of darkroom and screens
Written protocol for maintaining darkroom cleanliness, cassettes and screens clean, free from blemishes
Radiographer Ref 12
3.8.2 Condition of cassettes and screens
12 monthly Screen type, speed and date of installation Identification (cassette no.) and light tightness
Radiographer Ref 12
3.8.3 Darkroom fog Acceptance, 6 monthly & when fault reported
Density difference ≤ 0.05 for 2 minutes
Radiographer Ref 12
3.8.4 Relative speed of intensifying screens
Before initial use & 24 monthly
Baseline minus 10% Radiographer Ref 12
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL15
3.9 Dental RadiographyIntral oral, Panaromic and Cephalometric3.9.1 Filtration (HVL) Acceptance and
after equipment service
Table 3 Medical Physicist/ Service Provider
Ref 6, 12
3.9.2 Radiation output repeatability
Acceptance and 24 monthly
The actual peak X-ray tube voltage should not deviate from the indicated or selected value by more than 5%, or by the value specified by the manufacturer. It must not be possible to set or operate the X-ray tube with the tube voltage below 50 kilovolts (peak).
Medical Physicist/ Service Provider
Ref 6, 12
3.9.3 Beam alignment and collimation
Acceptance and 24 monthly
The primary radiation beam must be collimated in size at the end of the applicator to a circle not more than 7 cm in diameter
Medical Physicist/ Service Provider
Ref 6,12
3.9.4 Irradiation switch Acceptance and 24 monthly
There must be an irradiation switch to start and terminate X-ray production. This switch must be of a type that requires continuous pressure by the operator to produce X-rays. Where the irradiation switch is a foot switch it must be so constructed that operation of the X-ray tube cannot occur inadvertently should the foot switch be overturned. Where the irradiation switch is mounted at the end of a cable, the cable must be of sufficient length to enable the operator to stand at least 3 metres from the tube housing and the patient. If the switch is in a fixed location, it must be at least 3 metres from the tube housing
Medical Physicist/ Service Provider
Ref 6, 12
3.9.5 Focal spot to skin distance
Acceptance and 24 monthly
A position-indicating device must be provided to limit the minimum focal spot to skin distance to not less than 18 cm. The applicator must be an open-ended type. Pointed cone or close-ended applicators must not be used
Medical Physicist/ Service Provider
Ref 6, 12
3.9.6 Exposure timer reproducibility
Acceptance and 24 monthly
coefficient of variation ≤5% Medical Physicist/ Service Provider
Ref 6, 12
3.9.7 Exposure timer accuracy
Acceptance and 24 monthly
Limit: ≤10 % error for I-O units ≤ 5% error for all other units
Medical Physicist/ Service Provider
Ref 6, 12
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL 16
3.9.8 X-ray tube leakage
Acceptance At every rating specified by the manufacturer, the air kerma from leakage radiation at a distance of 1 m from the focal spot, averaged over an area not exceeding 100 cm2, does not exceed 1mGy in one hour
Medical Physicist/ Service Provider
Ref 10
3.9.9 Total filtration Acceptance < 2.5 mmAl or less then manufacturers recommendation
Medical Physicist/ Service Provider
Ref 10
3.9.10 Slice thickness Acceptance and 12 monthly
±20% or 1mm (whichever is greater) Medical Physicist/ Service Provider
Ref 10
3.9.11 High contrast spatial resolution
Acceptance and 12 monthly
As per manufacturers recommendation
Medical Physicist/ Service Provider
Ref 10
3.9.12 Image uniformity Acceptance and 12 monthly
As per manufacturers recommendation
Medical Physicist/ Service Provider
Ref 10
3.9.13 Radiation output accuracy
Acceptance and 12 monthly
The actual peak X-ray tube voltage should not deviate from the indicated or selected value by more than 5%, or by the value specified by the manufacturer
Medical Physicist/ service Provider
Ref 10
3.9.14 Radiation output reproducibility
Acceptance and 12 monthly
±5 % Medical Physicist/ Service Provider
Ref 10
3.9.15 Radiation field size
Acceptance and 12 monthly
Maximum 2 mm deviation between the light field and the radiation field
Medical Physicist/ Service Provider
Ref 10
3.9.16 Dental cone beam CT: DAP
Acceptance and 12 monthly
As per manufacturers recommendation
Medical Physicist/ Service Provider
Ref 10
4. Table 3: HVL values (IAEA Material)X-ray tube voltage (kVp) 71 80 90 100 110 120 130 140 150
Minimum HVL (mmAL) 2.1 2.3 2.5 2.7 3.0 3.2 3.5 3.8 4.1
HALF-VALUE LAYERS for intermediate selected voltages are to be obtained by linear interpolation.DentalX-ray tube voltage (kVp) 60 70 80 2.3 90
Minimum HVL (mmAL) Intra Oral 1.5 1.5 2.3 2.5
Minimum HVL (mmAL) Panaromic and Cephalometric 1.8 2.1 2.3 2.5
DIAGNOSTIC X-RAY IMAGING SYSTEMS QUALITY CONTROL17
5. REFERENCES
1. AAPM report 29, Equipment requirement and quality control for mammography, 1990.
2. AAPM report 74, quality control in Diagnostic Radiology, 2002.
3. Department of health (DOH), Code diagnostic QC, version7, https://sites.google.com/site/
radiationcontroldoh.
4. Dosimetry in Diagnostic Radiology: An international code of practice. IAEA TRS 457.
5. European guidelines for quality assurance in breast cancer screening and diagnosis – fourth edition,
European Communities, 2006,
6. Health Canada’s Recommendations for a quality assurance program in Dental Radiography, sites.google.
com/site/introdentalradiographyi/page
7. IMAGING QUALITY ASSURANCE MANUAL Published by the Radiation Safety Office for the University of
Rochester Medical Center, Revision 1, Dated 3/05, http://extranet.urmc.rochester.edu/radiationSafety/ Î
Forms, Manuals & Posters Î Radiology QA Manual
8. KCARE; Protocols for QA of CR System – Routine and Annual; Protocols for QA of DDR Systems – Routine
and Annual, http://www.kcare.co.uk Î Education Î Protocols, CR system: Commissioning & Annual tests;
CR system: Routine QA tests; DDR system: Commissioning & Annual tests, and DDR system: Routine QA
tests.
9. Quality assurance programme for screen film mammography, IAEA Human Health series No.2, 2009.
10. Recommendation for the design of x-ray facilities and quality assurance in dental cone beam (CT) system,
J Holroyd and A Walker, North Western Physics, HPA-RPD-065
11. Ministry of Health and Social Services, Radiation Protection and Waste Disposal Regulations, 2011.
12. www.rpop.iaea/training material/ Radiation protection in Diagnostic and Interventional Radiology
13. www.IPEM.org.uk (institute of Physics and Engineering in Medicen) Recommended standards for routine
performance testing of diasnostic X-ray imaging systems report 91, 2005
Edition 1
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