radio 13-14
DESCRIPTION
radiologyTRANSCRIPT
digital rad
Which type of digital image receptor is most common at this time?
CID (charge injection device)
• CMOS/APS (complementary metal oxide semiconductor/active pixel sensor)
• CCD (charge-coupled device)
1copyright O 2013-2014- Dental Decks
RADIOLOGY
digital rad
Which of the following are advantages of direct digital radiography.
Select all that apply.
superior gray-scale resolution
' reduced patient exposure to x-radiation
•
increased speed of image viewing
'
lower equipment and film costs
• sensor size
• increased efficiency
• effective patient education tool
• enhancement of diagnostic image
RADIOLOGY
i
2
copyright © 2013-2014- Dental Decks
^>tA4S03lS
^
Digital imaging
• filmless imaging system
• method of capturing a radiographic image
with a sensor, breaking the image into electronic
pieces and presenting & storing the image using
a computer
Direct digital image production requires
• x-ray source
• digital intraoral sensor
• computer
• high-resolution monitor
• software & printer
Digital intraoral sensor
• small intraoral detector used to capture a
radiographic image
• when x-rays strike the sensor, an electronic
charge is produc ed on the surface of the
sensor, this electronic charge is digitized or
converted to digital form
• may be wired or wireless
• sensor transmits information to computer
Pixel or picture element
• discrete unit of information
• consists of a small electron well where the x-
ray or light energy is deposited upon exposure
(/digital image is composed ofpixejsh
• CCD (charge-coupled device)
(CCDTjHiarge-coupled device)
• most common digital image receptor
• in the intraoral sensor, a solid-state detector
that contains a silicon chip with an embedded
electronic circuit
• sensitive to light or x-rays
• 640 x 480 pixels in size
CMOS/APS (complementary metal oxide
semiconductor/active pixel sensor)
•Jatest development in direct digital sensor
tecnnSlogy
• externally identical to CCD
i • differs in the way pixel s are read
• • advantages include lower production cost of
* the chip, lower power requirement s & greater
'. durability
• • smaUef.acjtive
a r e a
f °
r image acquisition
VCIDjJfcharge injection device)
• another sensor technology
• silicon based solid-state imaging receptor
similar to CCD
• no computer is required to process the images
• system features CID x-ray sensor, cord and
plug that are inserted into a light source on a
camera platform
Advantages of digital imaging
• superior gray scale resolution
256 shades of gray used instead of the 16-25 shades
used with film
• reduced exposure to radiation
radiation exposure is 50% to 90% less than what is
used to expose E-speed film
• increased speed of image viewing
images can be viewed instantly which allows for
immediate intetpretation
• lower equipment and film cost
no need for purchase of film and related processing
supplies and equipment
• increased efficiency
allows dental professionals to be more productive;
image storage and communication are easier with
digital networking
• enhancement of diagnostic image
features such as colorization and zooming allow for
highlighting of conditions; the gray scale may be re-
YSBjed. (digital subtraction)
• effective patient education tool
the size of images displayed monitor are easier for
the patient to see; allows for chairside education and
interaction
8
' superior gray-scale resolution
' reduced patient exposure to x-radiation
> increased speed of image viewing
> lower equipment and film costs
' increased efficiency
' effective patient education tool
' enhancement of diagnostic image
Disadvantages of digital imaging
• sensor size
some sensors are thicker and less flexible than
film and may stimulate the gag reflex
• initial set up costs
significant initial cost for purchase of digital
equipment as well as maintenance and repairs
• resolution / image quality
conventional x-ray film has a resolution of 12
•n - 20 lp/mm (linepairs per millimeter); digital
Mmaging using a CCD has a resolution of 10
lp/mm; because human eye can only perceive 8
N> - 10 lp/mm — digital imaging performs at
least as well as traditional radiography
• infection control
some sensors cannot withstand heat steriliza
tion; barrier protection is required
• wear & tear
sensors are subject to damage, wear & tear and
have a limited lifespan
• legal issues
because digital images can be enhanced, there
may be legal implications
digital rad
A method of obtaining a digital image where the sensor captures the image
and immediately transfers it to a computer is termed:
indirect digital imaging
• direct digital imaging
• storage phosphor imaging
3
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RADIOLOGY
digital rad
A patient is extremely concerned about radiation exposure. Which of the fol
lowing is best for limiting the amount of exposure he will receive during a ful l
mouth series?
• use of digital imaging
• use of E-speed films
• use of F-speed films
• substitute a panoramic image for the ful l mouth series
4copyright © 2013-2014- Dental Decks
RADIOLOGY
' direct digital imaging
Digital imaging• filmless imaging system• methods of obtaining a digital image:direct and indirect
Direct digital imaging• required components- x-ray machine- intraoral sensor- computer & monitor• utilizes a sensor with a fiberoptic cable that islinked to a computer• sensor is placed intraorally and exposed tox-radiation
• images are captured via a sensor(CCD, CMOS/APS or CID)
• the sensor transmits the image to a computermonitor• images appear on monitor within seconds ofexposure• software is used to enhance & store the image
Indirect digital imaging• scanning of traditional films• storage phosphor imaging
Scanning of traditional films• required components- CCD camera- computer & monitor
• existing films are scanned and digitized using aCCD camera
• CCD camera scans radiograph, converts theimage and displays it on monitor• is inferior to direct digital imaging• image is a "copy" not an "original"
^ S t e a g e ,
phosphor imaging ss P£{>
• required components.-phosphor- coated plate
- electronic processor/scanner- computer & monitor• a "wireless" digital imaging system
• a reusable imaging plate coated with phosphorsis used instead of a sensor with a fiberoptic cable• plates are similar to intraoral film in size, shape& thickness• image recorded on plate
• after exposure, plate is placed in electronicprocessor where a laser scans the plate; imageis transferred to the monitor within time framenf'jQ.s.gcciridr
1
to
5 minutes
• also referred to as photo-stimulable phosphorimaging or PSP imaging
• use of digital imaging
Digital imaging
• requires LESS radiation than conventional films because the sensor is more sensitive to
x-rays than dental film
• exposure time for digital imaging is approximately 5-0% less than what is required for F-
speed film
• intraoral, panoramic and other extraoral films may all be obtained digitally
Intraoral film
speed
• E-speed film is no longer available
• Only D-speed film and F-speed film are available for use with intraoral radiography
• F-speed film is recommended by the ADA
Q * ^ £ ^ £ S d j £ 2
u
j
r e s
6p%_qf the exposure time of D-speed
Other ways to limit exposure to x-radiation
• proper prescribing of dental radiographs based on individual needs of patient
• use of lead apron & thyroid collar
• use
of proper dental x-ray equipment
• use of rectangular position-indicating device (PID)
• use of beam
alignment devices
• use of proper technique
• proper sensor handing
• proper image retrieval
image char
A radiograph that exhibits areas of black and white is termed high contrast
and is said to have a short contrast scale; a radiograph the exhibits many
shades of gray is termed low contrast and is said to have a long contrast scale.
To limit image magnification, the longest target-receptor distance and short
est object-receptor distance are used. ^He
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
5
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RADIOLOGY
image char
Rank the following from LEAST radiopaque to MOST radiopaque.
amalgam
• bone
• dentin
> maxillary sinus
• enamel
copyright © 2013-2014- Dental Decks
RADIOLOGY
• both statements are true
contrastthe difference in degrees of blackness (densi-
tjg£) between adjacent areas on a dental radi
ograph.• high contrast describes an image that ap
pears mostly black & white; shades of gray
are absent
• low contrast describes an image with
many shades of gray; few areas of black
and white
scales of contrast
the range of useful densities seen on a dental
radiograph.
short-scale contrast
describes a high contrast image
with densities of black & white
that results from using a .low
kilovoltage.^Mi l ium V ,
long-scale contrast
describes a low contrast image
with many shades of gray that
results from using a highkilo-
voltaee.
magnification
a radiographic image that appears larger than
the actual size of the object it represents; mag
nification is influenced by the target-receptor
distance and the object-receptor distance.
target-receptor distance -
• distance between the source of x-rays and
the image receptor ilm / W . * ^
• a longer PID
results in a longer target-recep
tor distance and helps to limit magnification
object-receptor distance
s
*f-
Q^
• distance between the tooth and the image
receptor
• the closer the receptor is to the tooth, the less
magnification is seen on the image
to limit magnification
• use a long target-receptor distance/I
target-
receptor distance
• use a short object-receptor distance/J, object
-receptor distance
bus cm
LOW CONTRAST •• LONG-SCALE CONTRAST
HV**t kvp
'image receptor=digital sensor or x-ray film
• s i n us — b o n e — d e n t i n — enamelfit
radiolucent structures
• lack density
• permit
the passage of x-radiation
• absorb very little x-radiation
more x-rays to the receptor*
• appear dark or black on an image
amalgam
radiopaque structures
• are dense
• resist the passage of x-radiation
• absorb the x-radiation
• allow few_xjay.s to reach the receptor
• appear light or white on an image
Examples of radiolucent structures/mate
rials — BLACK or DARK
• air space images
• soft tissue images
• canals
• foramens
• fossas
• sinuses
• sutures
• caries
• pulp cavities
• periodontal ligament space
• denture acrylic
• some composite restorations
Examples of radiopaque structures/mate
rials _ WHITE or LIGHT
• enamel
• dentin
•bone
• lamina dura
• septa
• tubercles
• tuberosities
• ridges
• processes
• amalgams, metal restorations
• implants
• gutta percha
LUCENT means TRANSPARENT and
suggests something that lacks density —
something that lacks density permits the pas
sage of x-rays & appears RADIOLUCENT
^ S
OPAQUE means NOT TRANSPARENT
and suggests something that is more dense
— something that is more dense resists
the
passage of the x-rays & appears RA
DIOPAQUE
*receptot=digital
sensor or x-ray film
misc.
Dental radiographs are the legal property of the:
patient
• dentist
• state
>
none of the above
7
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RADIOLOGY
misc.
A dental hygienist in your practice has an adult recall patient without evi
dence of caries who states she needs bite-wing x-rays because it has been 6
months since her last dental images. The hygienist should tell the pat ient
that:
• yes, she is correct, it is time for new x-ray images
• bite-wings should be taken only once per year, not twice
• images should be taken based on patient need instead of a set time frame
• none of the above
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RADIOLOGY
Dental radiographs
• original radiographs are legally theproperty of the dentist even though thepatient or an insurance company may havepaid for them• the radiographs are the property of thedentist because they are indispensable to thedentist as part of the patient record• radiographs should be kept indefinitely
Patient access to radiographs• patients have a right to reasonable accessof their dental radiographs
• access includes copies of original radiographs (not originals) forwarded to thedentist who will be responsible for the patient's dental care
• dentist
Patients who refuse dental radiographs
• when a patient refuses to have dental radiographs, the dentist must decide whetherdiagnosis and treatment can take placewithout the recommended radiographs• no document can be signed by the patientthat releases the dentist from liability
Very important: the patient record, including radiographs, is legal documentation of apatient's condition.
Patient record must contain documentation of
• informed consent• number & type of radiographs exposed• rationale for taking radiographs• diagnostic information obtained from in
terpretation
• images should be taken based on patient need instead of a set time
Prescribing dental radiographs
• the dentist is responsible for prescribing the number, type and frequency of dental ra
diographs
• each patient's condition is different and therefore each patient must be evaluated for
radiographs on an individual basis
• a radiographic examination should never include a set number and type of images at
a set interval
• guidelines for prescribing dental radiographs are published by the American Dental
Association (ADA) in conjunction with the Food & Drug Administrations (FDA)
• visit www.ADA.org for current guidelines
• patients with caries, periodontal disease, tooth mobility, pain and impacted teeth need
more frequent radiographic examinations
Guidelines for radiographs in the recall patient
with clinical caries or risk of caries
• bite-wings at 6 - 12 month intervals
with no clinical caries or risk of caries
• bite wings at 24 - 36 month intervals
with periodontal disease
• clinical judgement for radiographs needed to evaluate periodontal disease; selected
bite-wings & periapicals
normal anat
Identify the structures indicated in the images below.
Image 1 Image 2
Reprinted from Haring, Joen Iannucci and Laura Jansen: Dental Radiography:
Principles and Techniques: Third Edition. © 2000, with permission from Elsevier.
copyright © 2013-2014- Dental Decks
RADIOLOGY
normal anat
The coronoid process often appears on what periapical image?
•maxillary incisor
• maxillary molar
• mandibular incisor
• mandibular molar
10copyright €> 20 13-2014- Dental Decks
RADIOLOGY
Res
Image 1- hamulus v
• a.k.a. hamular process
• small, hook-like projection of bone
• extends ..fmm the medial Pterygoid
jg|atejof^e
m
sjp;hjenoidjbone
• located posterior to the maxillary
tuberosity
• appears radiopaque
• on a maxillary molar periapical image,
appears as a hook-like radiopaque struc
ture
• varies in length, shape & density
• not always visible, depends on receptor
placement
hamulus
' maxillary tuberosity
*b
Image 2- maxillary tuberosity
• rounded prominence of bone that ex
tends distal to the third molar region
• appears radiopaque
• on a maxillary molar periapical
image, appears as a rounded ra
diopaque bulge distal to the third
molar region
• varies in size, shape and density
• not always visible, depends on re
ceptor placement
maxillary molar
Coronoid process
• coronoid means "resembling the beak of a crow"
• large prominence of bone on anterior ramus of mandible
• is thin and triangular in shape
• serves as an attachment site for one of the muscles of mastication
• appears radiopaque
• on a maxillary molar periapical image, appears as a beak-shaped radiopacity located
inferior to, or superimposed over, the maxillary tuberosity
• varies in shape and density
• not always visible, depends on receptor placement
Reprinted from Haring, Joen Iannucci and Laura Jansen Lind: Radiographic
Interpretation for the Dental Hygienist. © 1993, with permission from Elsevier.
normal anat
Identify the structures labeled 1 - 8 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." y\
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RADIOLOGY
normal anat
Identify the structures labeled 1 - 7 on the image below.
"Courtesy Dr. Stuart C White, UCLA School of Dentistry." 1 2
copyright ©2013-2014-Dental Decks
RADIOLOGY
' answers 1-8 below
1. lateral wall of the incisive (nasopalatine) canal
radiopaque line
2. anterior wall of the maxillary sinus
radiopaque line
3. nasopalatine fossa
radiolucent space
4. floor of nasal fossa
radiopaque line
5. soft tissue outline of the nose
slightly radiopaque outline
6. lamina dura
radiopaque line
7. border of maxillary sinus
radiopaque line
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
8. periodontal ligament space
radiolucent line
• answers 1 -7 below
1. anterior nasal spine
radiopaque line
2..lateral wall of nasopalatine canal
radiopaque line
3. median palatal suture
radiolucent line
4. floor of nasal fossa
radiopaque line
5. incisive (nasoplatine) foramen
radiolucent structure
6. soft tissue outline of tip of nose
slightly ra^oplique'^uTrihe
7. alveolar crest
radiopaque line
"Courtesy Dr. Stuart C White, UCLASchool of Dentistry."
normal anat
Identify the structures labeled 1- 5 on the image below.
Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
13
copyright©2013-2014-Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1 - 8 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry.'
14
copyright © 2013-2014- Dental Decks
RADIOLOGY
• answers 1-5 below
1. nutrient canal
radiopaque
lines
2. bony trabecular plate
radiopaque line
3. inferior border of mandibular canal
radiopaque line
4. submandibular gland fossa
radiolucent space
5. inferior border of mandible
radiopaque structure
1. anterior wall of maxillary sinus
radiopaque line
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
< answers 1 - 8 below
2. inferior nasal conchae A -
radiopaque mass
3. floor of nasal fossa
radiopaque line
4. inferior border of zygomatic process of maxilla
j - shaped radiopaque line C/*
5. posterior wall of zygomatic process of maxilla
radiopaque line
6.jnieiifljLboxd£t:.QLzygoma # ^
radiopaque line
7. floor of maxillary sinus
radiopaque line
8. mucosa over alveolar bone
slightly radiopaque structure
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
normal anat
Identify the structures labeled 1- 7 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." .. _
copyright ©2013-2014- Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1- 4 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
16
copyright © 2013-2014- Dental Decks
• answers 1 - 7 below
1. lingual cusp of 1st premolar
radiopaque area
2. periodontal ligament space
radiolucent line
3. film holder
radiopaque area
4. genial tubercles
donut shaped radiopacity
5. lingual foramen
radiolucent circle
6. bony trabeculations
radiopaque lines
7. marrow space
radiolucent area
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
• answers 1 - 4 below
1. periodontal ligament space
radiolucent line
2. mental foramen
ovoid radiolucency
3. submandibular gland fossa
radiolucent area
4. film clip mark
radiolucent artifact
"Courtesy Dr. Stuart C. White, UCLASchool of Dentistry."
normal anat
Identify the structures labeled 1 - 3 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
17
copyright©2013-2014-Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1- 7 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 1 8
copyright e 2013-2014- Dental Decks
RADIOLOGY 18
• answers 1 - 3 below
1. cement-enamel junction (CEJ)
radiopaque line
2. mental foramen
ovoid radiolucency
3. submandibular gland fossa
large radiolucent area
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
1 . inferior nasal conchae
radiopaque mass
• answers 1- 7 below
2. anterior wall of maxillary sinus
radiopaque line
3. floor of nasal fossa
radiopaque line
4. maxillary sinus
radiolucent space
5. floor of maxillary sinus
radiopaque line
6.inferior border of the zygomaticTiV lll lll lWW II » IIIIMI ijitilllll mi I I . Nil,? ,
process of the maxillaradiopaque area
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
7. lingual cusp of 1st premolar
radiopaque band
normal anat
Identify the structures labeled 1- 6 on the image below.
Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 19
copyright © 2013-2014- Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1 - 6 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
20copyright C 2013-2014- Dental Decks
RADIOLOGY
• answers 1 - 6 below
1. floor of nasal fossa
radiopaque line
2. lateral wall
in incisive canal )
radiopaque line
3 .
ala
of nose
radiopaque line
4. anterior wall
of maxillary sinus
radiopaque line
5. maxillary sinus
radiolucent space
6. lingual cusp of 1st premolar
radiopaque band "Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
1. dentino-enamel junction (DEJ)
radiopaque line
' answers 1 - 6 below
2. periodontal ligament space
radiolucent line
3. lamina dura
radiopaque line
4. periodontal ligament space of
palatal root
radiolucent line
5. film holder
radiopaque area
6. mucosa over alveolar bone
slightly radiopaque structure
"Courtesy Dr. Stuart C. White, UCLASchool of Dentistry."
normal anat
Identify the structures labeled 1- 3 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
21
copyright ©2013-2014-Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1 - 4 on the image below.
Courtesy Dr. Stuart C. White, UCLA School of Dentistry."
copyright © 2013-2014- Dental Decks
RADIOLOGY
• answers 1-3 below
1. mandibular tori
radiopaque masses
2. lingual foramen
radiolucent circle
3. genial tubercles
donut shaped radiopacity
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
• answers 1 - 4 below
1. alveolar crest of bone
radiopaque structure
2. lamina dura
radiopaque line
3. periodontal ligament space
radiolucent line
4. bony trabeculations
radiopaque lines
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
normal ant
Identify the structures labeled 1- 8 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 2
3
= =
_ _ _ _ ^ _ _ ^ _ _ copyright ©2013-2014-Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1 - 9 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 24
copyright ©2013-2014- Dental Decks
RADIOLOGY
1. marrow space
radiolucent space
• answers 1- 8 below
2. periodontal ligament space
radiolucent line
3. bony trabecular plate
radiopaque line
4. lamina dura
radiopaque line
5. pulp canal
radiolucent space
6. alveolar crest
radiopaque area
7. dentin
radiopaque area"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
8. enamel
radiopaque area
1. dentin
radiopaque area
• answers 1 - 9 below
2. bony trabeculations
radiopaque lines
3. marrow space
radiolucent area
4. pulp canal
radiolucent space
5. periodontal ligament space
radiolucent line
6. lamina dura
radiopaque line
7. alveolar crest
radiopaque structure
8. enamel
radiopaque band
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
9. pulp chamber
radiolucent space
normal anat
Identify the structures labeled 1-12 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 25
copyright © 2013-2014- Dental Decks
RADIOLOGY
normal anat
Identify the structures labeled 1 - 8 on the image below.
"Courtesy Dr. Stuart C. White, UCLA School of Dentistry." 2
6
copyright © 2013-2014- Dental Decks
RADIOLOGY
• answers 1-12 below
1. bony trabeculations
radiopaque lines
2. marrow space
radiolucent area
3. tooth #10
maxillary lateral incisor
4. lamina dura
radiopaque line
5. dentin
radiopaque area
6. periodontal ligament space
radiolucent line
7. alveolar crest
radiopaque structure
8. pulp canal
radiolucent space
9. pulp chamber
radiolucent space
10. enamel
radiopaque band
ll«jraU£dJiJmdot
radiopaque circle
12. dentino-enameTjunction
radiopaque line
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
• answers 1- 8 below
1. tooth #3
maxillary first molar
2. amalgam restoration
3. plastic bite block
faint opacity
4. film dot
rounajradiolucency
5. black letters - PLS
indicates Kodak Ektaspeed plus film
6. lamina dura
radiopaque line
7. periodontal ligament space
radiolucent line
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
8. lamina dura
radiopaque line
normal anat
Identify the structures labeled 1 -15 on the image below.
"Courtesy Dr. StuartC. White, UCLA
School of Dentistry."
RADIOLOGY
27
copyright©2013-2014-Dental Decks
normal anat
Identify the structures labeled 1 -13 on the image below.
"Courtesy Dr. Smart
C. White, UCLASchool of Dentistry."
28
copyright © 2013-2014- Dental Decks
RADIOLOGY
answers 1-15 below
1. air in nasal fossa
raHTolucenTspace
2. nasal septum
radiopaque line
3-lateralwaU of nasal septum
medial wall of maxillary sinus
radiopaque lines
4. infraorbital rim
radiopaque line
5- wall of infraorbital canal
radiopaque line
6. pterveomaxillary fissure
radiolucent space
7. pterygoid spine of sphenoid
radiopaque line
8. zygomatic arch
radiopaque mass
9. posterior wall of maxillary sinus
radiopaque line
10 . posterior wall of the zygomatic
process of the maxilla
radiopaque line
11. ear lobe
radiopaque mass
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
12. inferior border of the mandibular canal
radiopaque line
13. anterior nasal spine
v-shaped radiopacity
14. inferior border of the mandible
radiopaque band
15. hyoid bone
radiopaque structure
• answers 1-1 3 below
1. tip of nose
radiopaque area
2. hard palate / floor of nasal fossa
radiopaque line
3. orbit
radiolucent area
4. hard palate / floor of nasal fossa
radiopaque line
5. floor of maxillary sinus
radiopaque line
6. soft palate
radiopaque structure
7. air between soft palate & tongue
radiolucent space
8.._dorsum of the tongue
radiopaque line
9. ghost ima^eofop^>ositerartius
^TndTcateTrjy radiopaque dote
10 .
mental foramen
ovoid radiolucency
11. shadow of cervical spine
diffuse opacity
"Courtesy Dr. Stuart C. White, UCLA
School of Dentistry."
12. submandibular gland fossa
broad radiolucent area
13. articular eminence / articular tubercle
radiopaque prominence
processing
The pattern of stored energy on an exposed film is termed the latent image;
this image remains invisible unt il it undergoes processing.
The function of the developer solution is to chemically reduce the exposed,
energized silver halide crystals to black metallic silver.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
29copyright©2013-2014-Dental Decks
RADIOLOGY
processing
Which ingredient in the fixer solution functions to remove all unexposed and
underdeveloped silver halide crystals from the emulsion?
• fixing agent
• acidifier
• hardening agent
• preservative
• none of the above
30copyright © 2013-2014- Dental Decks
RADIOLOGY
both statements are true
Film processing
converts the latent image to a visible image and
preserves the image on film
Latent
image
• the film emulsion absorbs x:
rays during ex-jffgnni «r^ W e s the energy,within the silver
halide crystals
• the stored energy forms a pattern and creates
an invisible image
• the pattern of stored energy cannot be seen
and is referred to as the latent image; it re
mains invisible until chemical processing
Black areas of the visible image
• appear radiolucent f-;y
• created by deposits of black metallic silver
• structures that permit the passage of the
x-ray beam allow more x-rays to reach the
film & energize more silver halide crystals
• more energized silver halide crystals result
in more deposits of black metallic silver
White areas of the visible image
• appear radiopaque ^?Ci
• results from .unexposed silver halide crystals
• structures that resist the passage of the x-ray
beam restrict or limit amount of x-rays that
reach the film resulting in no energized silver
halide crystals and no deposits of black metal
lic silver
Film processing steps
1. development - developer solution removes
halide portion of exposed silver halide crystals;
this reduction of exposed crystals results in pre-
cipitated.Wackjnel^icjy]yer 6^FJsJheopti-
mal temperature for developer)
2. rinsing - water removes developer & stops
development process
3. fixing - fixer solution removes unexposed sil
ver
halide crystals
& hardens the
film
4. washing - water removesaTTexcess chemi
cals from the emulsion
5. drying
Developer composition
• developing agent contains 2 chemicals hy-
Cdroquinone
& cloijj
hydroquinone slpjvly
con
verts silver halide crystals & generates black
tones ;elon-quickly converts silver halide crys
tals & generates gray tones
• preservative is Sodium sulfite; prevents oxi
dation of developer agents
• accelerator is sodium carbonate; activates
the developer & softens emulsion^
^t^*-*******
««..«——"""-'^
• restrainer ts;potassium bromide; prevents
developer from deveToping
unexposed crystals
Fixer composition
• fixing agent (a.k.a. clearing agent or
hypo) is^xliu^Jhiojul&teorammonium
t h i o s u l f a t e ; removes or clears" all un-
exposed & underdeveloped silver halide
crystals from emulsion; clears the film so
that black image produced by the devel
oper can be seen
• preservative is,si»{Uumjmlfite (same as
in developer); prevents the deterioration of
the fixing agent
• hardening agent is potassium alum;
shrinks and hardens the gelatin in the
emulsion
• acidifier is acj^ j ic id j ) r sulfuric acid;
neutralizes the alkaline developer and
stops development process & provides
necessary acidic environment for fixer
Safelighting
• lighting that is required in darkroom for
safe illumination while processing x-ray
film
Q
J
^JJQdak^BXd
t
£S^hMM?r with a
15-watt bulb at least 4 feet away from
working surface
• fixing agent
Film processing steps
1.
development
2. rinsing
3. fixing
4. washing
5. drying
Manual film processing
• a.k.a. hand processing or tank processing
• method used to process films where all
steps are performed manually
• equipment needed includes processing
tanks with covers, thermometer, timer,
film hangers and stirring rod
• typical processing times include:
5 min utes in developer —> 30 second rinse
—> 10 minutes in fixer —• at l e a s t d Q a n m -
utgsjriwash
• as a rule, fixing time is twice as long as
developing time
Automatic film processing
• method used to process films using
where all steps of film processing are au
tomated
• automatic processor is required
• total processing time is 4-6 minutes
processing
Your assistant has processed three panoramic films today. She noticed the
films are progressively getting lighter and lighter. What should be done to
correct the problem?
• decrease the temperature of the developer
• increase the temperature of the fixer
• replenish the developer
• process the films a second time
• decrease the time in the developer
31copyright S> 2013-2014- Dental Decks
RADIOLOGY
processing
Your assistant has just processed a film that appears too dark. Identify each of
the potential causes of this problem.
• inadequate time in developer
• excessive time in developer
• developer solution too cool
• developer solution too hot
• depleted developer
• concentrated developer
RADIOLOGY
32copyright 6> 2013-2014- Dental Decks
' replenish the developer
Replenisher solutions
• a replenisher is a superconcentrated solu
tion that is added to the existing processing
solutions to compensate for the loss of vol
ume and strength that occurs due to oxida-
tion
• '
:
-
r
'
• both the developer and fixer must be re-
plenished daily to maintain adequate fresh-
ness
• replenishment main tains adequate con
centrations of chemicals which ensures uni
form processing
• failure to use replenishing solutions results
in non-diagnostic radiographs
Processing solutions
• include developer, fixer & replenisher
• must follow manufacturer directions for
storage, mixing & replenishing
• the developer and fixer must be changed at
the same time every 3-4 weeks or more often
with high volume of processing
• tanks must be scrubbed and cleaned when
changing solutions
Developer solution life is affected by
• cleanliness of tank
• size of films processed
• number of films processed
• temperature
• evaporation
Depleted developer
• is weakened, lacks concentration
• does not fully develop the latent image
• produces a non-diagnostic image with red
uced density and contrast
• results in underdeveloped films
• underdeveloped films appear light
Underdeveloped film
• appears light
• causes
- time/inadequate time in developer
- temperature/developer too cool
- concentration/depleted developer
• solutions
- t i m e / time in developer
- temperature/t temperature
- concentration/replenish developer
• excessive time in developer
• developer solution too hot
• concentrated developer
Time and Temperature: Problems and Solutions
Example
Underdevelopedfilm
Overdevelopedfilm
Reticulation of
emulsion
Appearance
Light
Dark
Cracked
Problems
- Inadequate development time
- Developer solution too cool
- Inaccurate timer or thermometer
- Depicted or contaminateddeveloper solution
- Excessive developing time
- Developer solution too hot- Inaccurate timer or thermometer- Concentrated developer solution
Sudden temperature changebetween developer and water bath
Solutions
- Check development time
- Check developer temperature
- Replace faulty timer or thermometer
- Replenish developer with freshsolutions as needed
- Check development time- Check developer temperature- Replace faulty timer or thermometer
- Replenish developer with freshsolutions as needed
Check temperature of processing
solutions and water bath; avoid
drastic temperature differences
Reprinted from Iannucci, Joen M. and Laura Jansen: Dental Radiography Principles and Techniques. Fourth Edition, d
from Elsevier Saunders
2012, with permission
processing
Black branching lines appear on a processed him. Which of the following is
the most likely cause?
• fixer cut-off
• developer cut-off
• fingernail damage
• static electricity
• air bubbles
33copyright © 2013-2014- Dental Decks
RADIOLOGY
Dose equivalent is expressed in terms of:
• coulombs/kilogram (C/kg)
• gray
(Gy)
• sievert (Sv)
• quality factor (QF)
rad biology
RADIOLOGY
34
copyright © 2013-2014- Dental Decks
• static electricity
Film Handling: Problems and Solutions
Example
Developer
cut-off
Fixer
cut-off
Over
lapped
films
Air
bubbles
Fingernail
artifact
Finger
artifact
Static
,eh?ctricity
Scratched
film
Appearance
Straight white
border
Straight black
border
White or dark areas
appear on film where
overlapped
White spots
Black crescent-
shaped marks
Black fingerprint
Thin, black,
branching lines
White lines
Problems
Underdeveloped portion of
film due to low level of
developer
Unfixed portion of film due to
low level of fixer
Two films contacting each
other during processing
Air trapped on the film
surface after being placed in
the processing solutions
Film emulsion damaged by
the operator's fingernail during
rough handling
Film touched by fingers that
are contaminated with fluoride
or developer
- Occurs when film packet is
opened quickly
- Occurs when film pack i s
opened before the radiographer
touches a conductive object
Soft emulsion removed from
the film by a sharp object
Solutions
Check developer level before
processing; add solution if
needed
Check fixer level before pro
cessing; add solution if needed
Separate films so that no contact
takes place during processing
Gently agitate film racks after
placing in processing solutions
Gently handle films holding
them on the edges only
Wash and dry hands thoroughly
before processing
- Open film packet slowly
- Touch a conductive object
before unwrapping films
Use care when handling films
and film racks
Reprinted from lannucci, Joen M. and Laura Jansen: Denial Radiography Principles and Techniques. Fourth Edition. © 2012, with permissionfrom Elsevier Saunders
sievert (Sv)
Exposure measurement
• exposure refers to the measurement of ion
ization in air produced by x-rays
• roentgen (R)
is a way of measuring radia
tion exposure by determining the amount of
ionization that occurs in air
• R is limited to measurement in air
• there is no SI unit for exposure that is equiv
alent to the R
• exposure expressed in Coulombs per kilo
gram (C/kg)
Dose measurement
• dose refers to amount of energy absorbed
by a tissue
• rad is a unit of absorbed dose that is equal
to the deposition of 100
ergs/g of tissue
• the SI unit for rad is gray (Gy)
Dose equivalent
• rem is traditional unit of dose equivalent
used to compare the biologi&.£ffects_of dif
ferent Jypes
of radiation on a tissue or organ
• is the product of Gy x QF (quality factor)
specific for the radiation type
• for x-rays, QF=1
5Tumt
for rem is sievert (Sv)
Unit Definition Conversion
Traditional System (older system)
roentgen (R)
radiation
absorbed close
(rad)
1 rem = rads X QFroentgen
equivalent (in)
man (rem)
SI system (newer system)
lR = 87erg/g
1 rad = 100 erg
1R =
2.58X10 'C/kg
1 rad = 0.01 Gy
Coulombs
per kilogram
(C/kg)
gray (Gy)
sievert (Sv)
1 Gy = 0.01 J/kg
lSv = GyXQF | 1
1 rem = 0.01 Sv
1 C/kg = 3880 R
is*si«
rads
: Sv = 100 rerh>
rad biology
List the following cells from most RADIORESISTANT to most RADIOSENSITIVE.
muscle
small lymphocyte
skin
thyroid gland
35copyright © 2013-2014- Dental Decks
RADIOLOGY
rad biology
After the bombings of Hiroshima, there were many persons exposed to radi
ation. Symptoms such as hair loss did not occur until days following the ex
posure. The time between exposure and onset of symptoms is termed:
latent period
• period of cell injury
• recovery period
• cumulative effects period
36copyright © 2013-2014- Dental Decks
RADIOLOGY
muscle — thyroid gland — skin — small lymphocyte
• all ionizing radiations are harmful
to living tissues
• radiation produces chemical changes
that results in biologic damage in living
tissues
• not all cells respond to radiation in the
same manner
• cells respond to radiation based on mi
totic activity, differentiation and cell
metabolism
• cells that are dividing and immature
are most susceptible to radiation
• radiosensitive cells are susceptible to ra
diation exposure
• the most radiosensitive cell is the small
lymphjaq&e
• radioresistant cells are resistant to radi
ation exposure
• the most radioresistant cells are muscle
anrlnjejye
• radiation effects are classified as somatic
(occur in person irradiated) or genetic
(passed on to future generation)
Sensitivity Radiosensitive Radioresistant Cells Sensitivity
high
high
high
high
fairly high
fairly high
fairly high
small lymphocyte
bone marrow
reproductive cells
intestinal mucosa
skin
lens of eye
oral mucosa
muscle tissue
nerve tissue
mature bone/cartilage
salivary gland
thyroid gland
kidney
liver
low
low
fairly low
fairly low
fairly low
fairly low
fairly low
latent period
Mechanisms of radiation injury
• ionization & free radical formation are re
sponsible for cell injury
• free radical formation is the primary mecha
nism responsible for damage
Theories of radiation injury
• direct theory - cell damage results when ra
diation directly hits critical areas within the cell
& direct alteration of the cell occurs
• indirect theory - suggests that x-ray photons
are absorbed within the cell and cause the for
mation free radicals & toxins which result in cell
damage K- f*W+ wa - ^W , W * eeA i ,
Dose-response curve
• a dose-response curve is used to demonstrate
the response of tissues to the dose of radiation
received
• a threshold dose does not exist & response of
tissues is directly proportional to the dose
• injury from radiation depends on total dose,
.„dose ratej^anjount of tissue affected, cgjl sen
sitivity and age
Stochastic & nonstochastic effects
• stochastic effects occur as a direct function of
dose (cancer, genetic mutations)
• nonstochastic effects have a threshold and in
crease in severity with increased dose (hair loss,
decreased fertility)
Radiation injury sequence
• latent period - period of time between exposure
and onset of symptoms
• period of injury - follows latent period and may
result in cell death, change in cell function or ab
normal mitosis
• period of recovery - follows injury; depending on
a number of factors, cells can repair the damage
caused by radiation
Radiation effects
• short term effects occur when large amounts are
absorbed in a short period of time (not applicable
to dentistry)
• long term effects occur when small amounts are
absorbed over a long period of time; linked to in
duction of cancer, birth & genetic effects
• cumulative effects occur; radiation damage is ad
ditive and unrepaired damage accumulates in the tis
sues and leads to health problems (cancer, cataract
formation, birth defects)
Radiation effects on cells
• the cell nucleus is more sensitive to radiation than
cytoplasm; DNA is affected
• cell division is disrupted which may lead to dis
rupted cell function or cell death
• radiation causes cell death by damaging chromo
somes
rad biology
A patient with a large squamous cell carcinoma of the lateral border of the
tongue is scheduled for a radical neck dissection. Prophylactic extractions of
hopeless teeth must be done to prevent which of the following?
osteoradionecrosis
bisphosphonate osteoradionecrosis
• periodontal disease
• rampant caries
none of the above
37copyright © 2013-2014- Dental Decks
RADIOLOGY
rad biology
The most common oral problems that occur following radiation and
chemotherapy include mucositis, infection, pain and bleeding.
The oral cavity is irradiated during the course of treating radiosensitive oral
malignancies, usually squamous cell carcinoma.
• both statements are true
• both statements are false
> the first statement is true, the second is false
«the first statement is false, the second is true
38
copyright © 2013-2014- Dental Decks
RADIOLOGY
Definition
• most serious possible complication facing the
oral cancer patient
• condition of non-vital bone in a site of radio
therapy; bone dies as a complication of radio
therapy
• is not
an infection
Cause
• radiation therapy destroys cancerous cells but
also destroys normal cells, damag ing small ar
teries and reducing circulation
• insufficient blood supply to the irradiated area
decreases the ability to heal, and any subse
quent infections to the jaw can pose a huge
risk
to the patient
• patients receiving high dQjt££_Qf,xadiation
£>40 Gv) to the jaw area are at risk
Histologic features- 3 H's
v* hypocellular bone
v^hypovascular tissue
v""hypoxic tissue & bone
Prevention
• extr act all hopeless teeth 3 weeks prior to ra
diotherapy
• if extracting after radiotherapy, use of systemic
antibiotics is warranted
• hyperbaric oxygen treatments before and
after radiotherapy may be helpful
• osteoradionecrosis
Clinical features
• may involve the maxilla or mandible
• more common in the mandible
• most frequently occurs when an insult to the bone
is sustained in the irradiated area, such as related
subsequent surgery, biopsy, tooth extractions or
denture irritations
• may also be precipitated by periodontal disease
or occur spontaneously
• symptoms may include pain, swelling, reduced
mobility, drainage, exposed bone in the involved
area and destruction of bone
• symptoms may occur months or years after the
radiotherapy
Management
• difficult to manage
• preventio n is key
• debridement of infected bone may be required
• advanced cases may require radical surgery
• patients must be followed closely by physicians
and dentist regularly
• both statements are true
Radiation therapy of oral cavity
• used to treat radiosensitive oral malignant tu
mors, usually squamous cell
carcinoma
• indicated when the tumor is radiosensitive,
advanced, or, cannot be treated surgically be
cause it is deeply invasive
• fractionation
- total radiation dose is delivered in smaller
multiple doses
- provides greater tumor destruction than a sin
gle large dose
- allows for increased cellular r epai r of nor
mal tissues
- increases mean oxygen tension resulting
in
tumor cells that arc more radiosensitiveWMMIMM n
Radiation effects
on the teeth
• irradiation of developing teeth severely retards
growth
• adult teeth are radioresistant\3^<'
Radiation effects on bone
• irradiation of bone results in damage to the
fine vasculature
• normal marrow may be replaced with fatty
maiTOW
or fibrous connective tissue
• necrosis may occur and exhibits loss of os
teoblastic and osteoclastic activity
Radiation effects on oral tissues Ks
• occurs by end of 2
nd
weekpf
therapy *5»jf
• mucositis results; appears as areas of redness and
inflammation
• as therapy continues, the oral tissues break down
resulting in formation of white pseudomembranes
• oral condition worsens with continued therapy
and candidiasis often occurs
• following therapy, oral tissues heal within ap-
proximately 2 months ifogut 8
Radiation effects on taste buds /-'
• taste buds are radiosensitive
• radiation therapy damages taste buds
• a loss of taste may first occur during the 2
nd or
3
rd week of radiation therapy
Radiation effects on salivary glands
• radiation therapy damages salivary gland tissues
• there is a m ark ed & progressive loss of salivary
secretion; extent of reduced flow is dependent on
dose
• causes decreases in saliva, p H
& buffering ca
pacity
• causes increased viscosity
• dry moutn (xerostomia) results & makes the pa
tient susceptible to radiation caries - a rampant
form of caries
• xerostomia causes tenderness of oral tissues and
difficulty in swallowing
rad char
In the dental x-ray tube, the number of electrons flowing per second is meas
ured by:
• kilovoltage peak (kVp)
• milliamperage (mA)
• time (in seconds)
• all of the above
39
copyright © 2013-2014- Dental Decks
RADIOLOGY
rad char
When the PID length is changed from 8
to 16 , the target-receptor distance
is doubled. According to the Inverse Square Law, the resultant x-ray beam is:
• 1/4 as intense
• 1/8 as intense
• four times more intense
• eight times more intense
• none of the above
40
copyright e 2013-2014- Dental Decks
RADIOLOGY
W ~
TJu^-^ milliamperage (mA)
^rrv*4
^ V t i
x_
ra y beam intensity
time and distance
x-ray beam quality & kVp
• quality refers to the average energyor 7
intensity is the total energy contained in
penetra tin g power of the x-ray beam and the x-ray beam at a specific area at a given
is controlled by the kilovoltage peak (kVp) time
• kVp controls the speed & energy of the ~ Qrfntensity is affected by kVp, m A , exposure
electrons and determines the penet rating
power of the beam £>
• kVp range for dental radiography is s k ^
c^iookv^i Tt<y
x-ray beam quantity & mA ™ « - * .
• quantity refers to the number of x-rays J ^ ^ H , a*
1
produced and is controlled by the mil-' e
\^
l
%
liamperage (mA)
• mA
controls the amperage of the fila
ment current and the amount of electrons
that pass through the filament
• mA
controls the temperature
of the fil
ament
• as the mA increases, more electrons pass
through the filament and more x-rays are
produced
• J T I A range for dental radiography is
j ^ l 5 m A P
^ TiHmmiini iM urn
to remember, think alphabeti cal order ...
kVp= quali ty ( k & 1)
mA = quan tity ( m & n )
Adjustment
T
1
r
i
T
i
kVp
kVp
mA
mA
time
time
Film
appears
darker
lighter
darker
lighter
darker
lighter
to INCREASE film density & make it darker,
INCREASE:
• mA
•kVp
• time
to DECREASE film density & make it lighter,
DECREASE:
• mA
•kVp
• time
Inverse Square Law
• defined as:
the intensity of the radiation is inversely
proportional to the square of the distance
from the source of radiation
• inversely proportional means that as one
variable increases, the other decreases
• when
the target-receptor distance is in
creased, the intensity is decreased
original intensity . new intensity
new distance2 original distance
2
OS
V£
closer
Reprinted from lannucci, Jocn M. and Howerton,Laura Jansen: Dental Radiography Principles andTechniques. Fourth edition © 2012, with permissionfrom Elsevier Saunders.
• 1/4 as intense
Example:
If the PID
length is changed from 8" to 16", how
does this increase in target-receptor distance af
fect the intensity of the beam?
plug numbers into the mathematical for
mula:
x /82
4*
/
U
K
IW
solve for x
1 / x= 162 / 8
2
1 / x= 256 / 64
1 / x= 4 / 1
x= 1/4 answer
• doubling the distance results in a beam that
is % as intense
• the x-ray beam that exits an 8" PID is more
intense than one the exits a 16 " PID (see dia
gram)
The distance traveled by the x-ray beam affects
the intensity; distances to be considered include
the following:
• target-surface distance is the distance from
the source of radiation to the surface of the pa
tient's skin
• target-object distance is the distance from
the source of radiation to the tooth
• target-receptor distance is the distance from
the source of radiation to the receptor ffilm or
sensor)
rad char
A 6'5 muscular male with a large mandible requires a complete series of den
tal images. You plan to increase the kVp because of his size. Identify each of
the following that results with the increased kVp:
• a more penetrating beam
' a less penetrating beam
• a reduced subject contrast
• an increased subject contrast
• long scale contrast
• short scale contrast
41copyright © 2013-2014- Dental Decks
RADIOLOGY
rad char
Identify each of the following that influence the density of an image:
•kVp
• mA
• exposure time
• use of a 2 film packet
42
copyright©2013-2014-Dental Decks
RADIOLOGY
Increased kVp
• produces x-rays with increased energy
(speed) and shorter wavelength
• increases the penetrating power of the x-
ray beam
• is needed for larger patients with large
bones and significant amounts of soft tissue
• results in increased density (makes image
darker)
• results in reduced or low contrast which is
long-scale contrast
Contrast
• refers to how sharply dark and light areas
are separated or differentiated on an image
• the difference in degrees of blackness be
tween adjacent areas on a dental radiograph
• a more penetrating beam
• a reduced subject contrast
• long scale contrast
Long-scale contrast
• LONG scale =
JLOW contrast =
LOTS of gray
• a low contrast image exhibits many shades
of gray
• a low contrast image does not exhibit black
& white
Adjustment
T
(High)
4(Low)
kVp
kVp
Contrastscale
LONG
lots of gray
SHORT
black & white
Contrast
LOW
HIGH
Contrast & kVp
• adjustment of kVp affects contrast
• with low kVp (65-70), a high contrast
image results
• with high kVp (90), a low contrast image
results
Patient size & kVp
• large patients need increased kVp;
if not increased — image appears LIGHT
• small patients need decreased kVp;
if not decreased — image appears DARK
Density description
• a visual characteristic of a radiographic
image
• overall blackness or darkness of an image
• when a dental image viewed, the relative
transparency of areas depends on the distri
bution of black silver particles
• density is the degree of.silver blackening
• an image of correct density allows one to
view the black areas (air space images),
white areas (enamel, dentin, bone) and gray
areas (soft tissue)
Factors that influence density
• exposure factors
-kVp
- mA
- exposure time
• thickness of subject
adjustments in kVp, mA and exposure time
can be made to compensate for size variations
• an increase in any exposure factor , sepa
rately or combined, increases the density of
an image
\9
Adjustment
T
4
r
4.
T
4
tx
4
kVp
kVp
mA
mA
time
time
thickness
thickness
••
.
kVp
mA
exposure time
Densitv Film
t
4
t
4
T
4
4
T
appears
darker
lighter
darker
lighter
darker
lighter
lighter
darker
Size of patient
• thickness of subject also affects density;
with a large patient (thick bones, excess soft
tissue), fewer x-rays reach the receptor and
as a result, the image appears lighter
• with increased thickness, a decreased den
sity results
• with decreased thickness, an increased
density results
Note: the use of a 2-film packet does not affect
the density of the image
rad physics
Which of the following converts electrons into x-rays?
• positive anode
1 negative anode
' positive cathode
• negative cathode
43copyright © 2013-2014- Dental Decks
RADIOLOGY
rad physics
Which of the following focuses the electrons into a narrow beam and directs
the beam across the tube toward the tungsten target of the anode?
• copper stem
• tungsten filament
• insulating oil
• molybdenum cup
• lead collimator
44
copyright©2013-2014-Dental Decks
RADIOLOGY
•positive anode
X-ray tube• heart of the x-ray generating system
• critical to the production of x-rays
• glass vacuum tube from which all the air has
been removed
• component parts include leaded glass hous-
_ing, negative cathode & positive anode
Leaded-glass housing
• leaded-glass vacuum tube that prevents x-rays from escaping in all directions
• a "window" permits the x-ray beam to exitthe tube
Reprinted from Iannucci, Jocn M. and Howerton, Laura
Jansen: Dental Radiography Principles and Techniques.
Fourth edition © 2012 with permission from Elsevier-Saun-
ders.
to remember,think CATNAP...
cathode is negative
| Cathode/negative electrode
• supplies electrons necessary to generate x-rays
• consists of a tungsten wire filament in amolybdenum cup-shaped holder
• tungsten filament (coiled tungsten wire)
produces electrons when heated
• molybdenum cup focuses the electronsinto a narrow beam and directs the beamacross the tube toward the tungsten target ofthe anode
Anonode/positive electrode•odeisTnto x-• converts electronslivto x-ray photons
• consists of a wafer-thin tungsten plate em
bedded in a solid copper rod
• tungsten target serves as a focal spot and
converts bombarding electrons into x-ray
photons
• copper stem functions to dissipate the heat
away from the tungsten target
molybdenum cup
Production of x-rays
• tungsten filament is heated and electrons
are produced
• molybdenum cup focuses the electrons
into a narrow beam and directs the beam to
wards the tungsten target in the anode
• x-rays are generated when the beam is sud
denly stopped by the tungsten target
•4fafi.en£igy_of motion is converted to x-ray
energy (1%) and heat (99%)
• insulating oil that surrounds the x-ray tube
absorbs the heat
• x-rays that are produced are emitted in all
directions; leaded-glass housing of tube pre
vents the x-rays from escaping
• small number of x-rays exit the x-ray tube
through the unleaded glass window area
• x-rays travel through unleaded glass win
dow, through the tubehead seal and then the
aluminium disks
• the lead collimator restricts the size of the
beam and the x-ray beam travels down the
lead lined position -indicating device (PID)
and exits at the opening
Reprinted from Haring, Joen Iannucci and Laura lansen: Dental Radiogra
phy: Principles and Techniques: Third Edition. © 2000, with permission front
Elsevier.
Component functions
• tungsten filament of cathode produces
electrons when heated
• molybdenum cup of cathode focuses the
electrons into a narrow beam and directs
the beam towards the tungsten target in the
anode
• tungsten target in anode stops the elec
trons and converts the energy into x-rays &
heat
•(copper stenijjserves to dissipate the heat
that is createdwith the production of x-rays
|i_Metal
ji housing£ of x-ray1 tube-
1
J
a-lnsulating
: oil
K. . -
Lead Unleaded glasscollimator window of
x-ray tube
'osition
indicating
device
rad physics
Identify each of the following that are properties of x-rays:
• no weight
• travel at speed of sound
• have no charge
• cannot be deflected or scattered
• are invisible
• are absorbed by matter
• do not damage living cells
• do not cause fluorescence45
copyright O 2013-2014- Dental Decks
RADIOLOGY
rad physics
Rectification is the conversion of a direct current (DC) to an alternating cur
rent (AC).
The dental x-ray tube acts as self-rectifier in that in changes DC to AC while
producing x-rays.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
46copyright ® 2013-2014- Dental Decks
RADIOLOGY
Properties of x-rays
• appearance
invisible and cannot be detected by
any of the senses
• mass
have no mass or weight
• charge
have no charge
• speed
travel at the speed of light
• wavelength
travel in waves and have short wave
lengths with a high frequency\V""
• path of travel
travel in straight lines and can be de
flected, or scattered
• focusing capability
cannot be focused to a point and al
ways diverge from a point
• no weight
• have no charge
• are invisible
• are absorbed by matter
• penetrating power
can penetrate liquids, solids, and gases;
the composition of the substance deter
mines whether x-rays penetrate or pass
through, or are absorbed
• absorption
absorbed by matter; the absorption de
pends on the atomic structure of mat
ter and the wavelength of the x-ray
• ionization capability
can interact with materials they pene
trate and cause ionization
• fluorescence capability
can cause certain substances to fluo
resce or emit radiation in longer wave
lengths (e.g., visible light and
ultraviolet light)
• effect on film
can produce an image on photographic
film
• effect on living tissues
cause biologic changes in living cells
• electricity is the energy used to make x-
rays; electrical energy consists of a flow of
electrons through a conductor; this flow is
known as the electrical current
• electrical current is termed direct current
(DC) when the electrons flow in one direc
tion through the conductor
• alternating current (AC) describes an elec
trical current in which the electrons flow in
two, opposite directions
• rectification is the conversion of AC to DC
• dental x-ray tube acts as a self-rectifier in
that it changes AC into DC while producing
x-rays; ensures that current is always flowing
in the same direction from cathode to anode
• amperage is the measurement of the num
ber of electrons moving through a conductor,^,
c7irrentls~measured in amperes (A) or mil-
liampcres (mA)
• voltage is the, measurement of electrical
force that causes electrons to move from a
negative pole to a positive one; measured in
volts (V) or kilovolts (kV)
• circuit is a path of electrical current; two
electrical circuits are used to produce x-rays:
a low-voltage/filament circuit and a high-
voltage circuit
* % .
• both statements are false
• low voltage/filament circuit uses 3 to 5
volts, regulates the flow of electrical current
to the filament; controlled by mA settings
• high-voltage circuit uses 65,000 to 100,000
volts, provides the high voltage required to
accelerate; controlled by kVp settings
• transformer is a device that is used to either
increase or decrease the voltage in an electri
cal circuit; it alters the voltage of the incom
ing current and then routes the electrical
energy to the x-ray tube; three types of trans
formers are used to adjust the electrical cir
cuits (see below)
• step-down transformer is used to decrease
the voltage from the incoming 110- or 220-
line voltage to the 3 to 5 volts used by the fil
ament circuit
• high-voltage circuit uses both a step-up
transformer and autotransformer
• step-up transformer is used to increase the
voltage from the incoming 110- or 220-line
voltage to the 65,000 to 100,000 volts used
by the high-voltage circuit
• autotransformer serves as a voltage com
pensator that corrects for minor fluctuations
in the current
rad physics
Which of the following occurs only at 70 kVp or higher and accounts for a very
small part of the x-rays produced in the dental x-ray machine?
• compton
scatter
• coherent scatter
• characteristic radiation
• general (Bremsstrahlung) radiation
47copyright ©
2013-2014-
Dental Decks
RADIOLOGY
rad protection
Identify each component of inherent filtration:
• insulating oil
• unleaded glass window
• lead lined PID
• tubeheadseal
48
copyright © 2013-2014- Dental Decks
RADIOLOGY
> characteristic radiation
Types of x-rays
• not all x-rays produced in the x-ray tube are
the same; x-rays differ in energy and wave
length
• energy and wavelength varies based on how
the elections interact with the tungsten in the
anode
• kinetic energy_of electrons isconverted to
x-ray photons via general (braking or Brem-
sstrahlui'g) radiation or characteristic radiat-
ion
• genera l/braking radiation is produced
when speeding electrons slow down due to in
teractions with the nuclei of the tungsten tar
get atoms
- braking refers to the sudden stopping or
slowing of high-speed electrons when they
hit or come close to the tungsten target
- 70% of the x-ray energy produced is gen
eral radiation
• characteristic radiation is produced when
a high-speed electron dislodges an inner-shell
electron from the tungsten atom and causes
ionization " I
- the remaining electrons rearrange to fill the
vacancy resulting in a loss of energy & pro
duction of x-ray photon
- only a small % of x-rays produced; occurs
only at > 70 kVp
Definitions
• primary radiation is the penetrating x-ray
beam that is produced at the target of the
anode and exits the tubehead; a.k.a. primary
or useful beam
• secondary radiation is x-radiation that is
created when the primary beam interacts with
matter; ig less penetrating thanprimaryradia-
tion
• scatter radiation, a form of secondary rad
iation, is the result of an x-ray deflected from
its path by the interaction with matter; deflect
ed in all directions by the patient's tissues;
detrimental to tissues
• id Compton scatter] ionization takes place;
& \§ an x-ray photon collides with an n outer-shell
C *> > electron and gives up part of its energy to
'£ eject the electron from its orbit; x-ray photon
•*J*Hoses energy and continues in a different dir-
% ection (scatters) at a lower energy level; ac
counts forJ>2% of the scatter that occurs
• coherent or unmodified scatter occurs
when a low-energy x-ray photon interacts
with an outer-shell electron; no change in the
atom occurs; x-ray photon of scattered radiat
ion is produced; x-ray photon is scattered in
a different direction from that of the incident
photon; noJoss of energy and no ionization
occur; accounts for 8% of the interactions
insulating oil
< unleaded glass window
' tubehead seal
• inherent filtration takes place when the
primary beam passes through the glass
window of the x-ray tube, the insulating
oil, and the tubehead seal
• inherent filtration of the dental x-ray
machine is approximately 0.5 to 1.0 milli
meter (mm) of aluminum
• inherent filtration alone does not meet
the standards regulated by state and federal
laws; added filtration is required
OvtiioKjljtJ
. i
OMMUMHW <k<»
4r
^> -s tow e*<av*
Reprinted f rom Iannucci,
Joen
M. and Howerton, Laura Jansen: D e n ^ '
**^5l$
lal Radiography Principles and Techniques. Fourth edition © 2012 (/
willi
permission from Elsevier-Saunders.
Aluminum filter
~
r>K
- 1
Long and short
wavelengths
Shortwavelenotbs
Enlargement o detail
• added filtration refers to the placement
of aluminum discs in the path of the x-
ray beam between the collimator and the
tubehead seal
• aluminum discs can be added to the
tubehead in 0.5 mm increments
• purpose of the aluminum discs is to fil
ter out the longer-wavelength, low-en
ergy x-rays from the x-ray beam
• low-energy, longer wavelength x-rays
are harmful to the patient and are not
useful in diagnostic radiography
• filtration of the x-ray beam results in
a higher energy & more penetrating
useful beam
• state and federal laws regulate the re
quired thickness of total filtration = in
herent filtration + added filtration
• dental x-ray machines operating at ,<
70 kVp require a minimum total of 1.5
mm aluminum filtration
• dental x-ray machines operat ing at
> 70 kVp require a minimum total of 2.5
mm aluminum filtration
rad protection
Identify each of the following that is recommended for operator protection
during exposure.
•
stand 3 feet away from x-ray tubehead
• stand at a 45-75 degree angle to the beam
• wear a lead apron
•
stand behind a barrier
•
hold the
PID
• hold the film if the patient cannot stabilize it
49
copyright © 2013-2014- Dental Decks
RADIOLOGY
rad protection
Prior to x-ray exposure, the proper prescribing of radiographs and the use of
proper equipment can minimize the amount of radiation that a patient re
ceives.
Radiographs must be prescribed by the dentist based on the individual needs
of the patient.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
50
copyright © 2013-2014- Dental Decks
RADIOLOGY
rad protection
Identify each of the following that is recommended for operator protection
during exposure.
• stand 3 feet away from x-ray tubehead
• stand at a 45-75 degree angle to the beam
• wear a lead apron
• stand behind a barrier
•holdthe PID
• hold the film if the patient cannot stabilize it
49copyright © 2013-2014- Dental Decks
RADIOLOGY
rad protection
Prior to x-ray exposure, the proper prescribing of radiographs and the use of
proper equipment can minimize the amount of radiation that a patient re
ceives.
Radiographs must be prescribed by the dentist based on the individual needs
of the patient.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
50copyright © 2013-2014- Dental Decks
RADIOLOGY
Operator protection guidelines
• must use proper protection during exposure
to avoid the primary beam, scatter radiation
etc.
• must avoid the primary beam
• distance, position and shielding are all im
portant for protection
Distance recommendations
• must stand at least 6' away from the tube-head
• if distance is not possible, a protective bar
rier must be used
Primary beam
Y '
.••••.. ' -:.,.\:.-: ••:::•-::•• ' '
l W
'
Radiographer
135
Reprinted
from Iannucci, Joen
M. and Howerton, Laura Jansen:
Dental Radiography Principles and Techniques. Fourth edition
•D 2012 with permission from Elsevier-Saunders.
• stand behind a barrier
Position recommendations
• must stand perpendicular to the primary
beam, or, at a £0-135 degree angle to the
beam ' •
• never hold a film in place for a patient dur
ing exposure
• never hold the PID during exposure
Shielding recommendations
• whenever possible, stand behind a protec
tive barrier, such as a wall
Maximum permissible dose (MPD)
• MPD is the dose of radiation the body can
endure with little or no injury
• for non-occupationally exposed person limit
is 0.001 Sv/year
• for occupationally exposed person limit is
0.05 Sv/year
• for occupationally exposed pregnant person
— limit is 0.001 Sv/year
ALARA concept
•As Low As Reasonably Achievable concept
states that all exposure to radiation must be
kept to a minimum
• applies to patients & operators
Patient protection before exposure
• proper prescribing of dental radi
ographs
• use of proper equipment including
filtration, collimation and PID
• the rectangular PID (instead of
round) is most effective in reducing pa
tient exposure
• use of a long PID is more effective
than use of a short PID
Patient protection during exposure
• use of thyroid collar for intraoral
films and lead apron for all films
• use of digital imaging or use fastest
film
available (F-speed)
• use of beam alignment devices
• use of correct exposure factors (kVp,
mA & exposure time)
• use of proper technique
• both statements are true
Patient protection after exposure
• proper sensor or film handling
• proper image retrieval or film pro
cessing
Guidelines for prescribing of dental
radiographs
• dentist is responsible for ordering im
ages & uses professional judgment to
make decisions concerning the num
ber, type and frequency of dental radi
ographs
• radiographic exam should never in
clude a predetermined number of
films
• radiographs should never be taken at
predetermined time intervals
• radiographs should be ordered based
on the individual needs of the patient
• guidelines for prescribing dental ra
diographs have been determined by
the ADA and FDA
rad protection
Which of the following is used to restrict the size and shape of the x-ray beam
and to reduce patient exposure?
• aluminum discs
• collimation
• inherent filtration
• total filtration
51copyright
€>
2013-2014- Dental Decks
RADIOLOGY 51
tech
If a processed film appears light with herringbone or tire track pattern on it,
which of the following is the likely cause?
• the film was bent during placement
• the film was reversed (placed backwards) during exposure
• the film was exposed twice
• the patient moved during exposure
52
copyright © 2013-2014- Dental Decks
RADIOLOGY
collimation
Collimation
• used to restrict the size and shape of
the x-ray beam & to reduce patient
exposure
• a collimator is a lead plate with hole
in the middle, is fitted over the open
ing of the machine housing where the
beam exits
• collimator may have a round or rec
tangular opening
• rectangular collimator restricts the
size of the beam to slightly larger than
a size 2 film and significantly re
stricts patient exposure
• circular collimator produces a cone
shaped beam & restricts the size of the
beam to 2.75" in diameter
• when using a circular collimator, fed
eral regulations re quire that the
beam be restricted to 2.75" as it exits
the PID and reaches the skin of the pa
tient
Position indicating device (PID)
• the PID or cone is an extension of the
x-ray tubehead used to direct the
beam
• types of PID include conical, round
and rectangular
• a conical PID is a closed plastic cone
that produces scatter radiation;no longer
used in dentistry
• a round PID is a tubular open ended
lead- lined extension; no PID scatter is
produced
• a rectangular PID is a rectangular
open ended lead-lined extension; is
most effective in reducing patient ex
posure; no PID scatter is produced
• both round and rectangular PIDs are
available in two lengths: short (8")
and long (16")
^ VtMJangPID
is preferred because less
V'uivergence of me*x-ray beam occurs
• the film was reversed (placed backwards) during exposure
A reversed
film is light &
exhibits a
herringbone
pattern.
A double exposure appears dark &
exhibits a double image.
A bent film appears stretched & distorted. With movement of the patient or PID, a blurred
image results.
Images reprinted from Iannucci , Joen M. and Howerton, Laura Jansen: Dental Radiography Principles and Techniques. Fourth edition © 2012
with permission from Elsevier-Saunders.
tech
Of the following factors that influence the geometric characteristics of an
image, which one is NOT able to be changed by the operator?
• target-receptor distance
• object-receptor distance
• film composition
• focal spot size
• object-receptor alignment
53copyright© 2013-2014- Dental Decks
RADIOLOGY
tech
A periapical image shows stretched and elongated maxillary central incisors.
Which of the following is the likely cause?
• vertical angulation is excessive/too steep
• vertical angulation is insufficient/too flat
• incorrect horizontal angulation
• any of the above
54
copyright © 2013-2014- Dental Decks
RADIOLOGY•-.
• focal spot size
Magnification
• enlargement of an image that results
from the divergent paths of x-ray beam
• some degree of magnification is pre s
ent in every image due to divergent paths
• influenced by target-receptor distance
and object-receptor distance
• target-receptor distance (or source to
receptor distance) is the distance be
tween the sou rce of x-rays & image re
ceptor
• PID determines target-receptor distance
• shorter PID results in more magnifi
cation; longer PID results in l e s s j n a g n i -
JBcatjori
• object-receptor distance is the dis
tance between the tooth & image recep
tor
• if there is decr eased dist ance between
the tooth & receptor, less magnification
occurs
• if there is increased distance between
the tooth & receptor, more magnification
occurs
Focal spot size
• tungsten target in anode is focal spot
• size ranges from0.6
-1.0 minj^nd
is de
termined by the manufacturer (cannot be
controlled by operator)
• the size of focal spot influences the
image sharpness
• the smaller the focal spot, the sharper
the image
In dental radiography, the most accurate
image:
• use the smallest focal spot size
• use the L ONG EST target-receptor dis
tance
• use the SHORTEST object-receptor
distance
• direct the central ray of the x-ray beam
perpendicular to the receptor and tooth
• keep the receptor parallel to the tooth
being imaged
• vertical angulation is insufficient/too flat
Vertical angulation
• refers to the positioning of the PID in a
vertical, or up-and-down plane
• correct vertical angulation results in an
image that is the same
length as the tooth
• incorrect vertical angulation results in
ELONGATION or FORESHORTENING
• an elongated image appears long & results
from too flat vertical angulation
• a foreshortened image appears short & re
sults from too steep vertical angulation
• 0 degree vertical angulation = PID parallel
with floor
• positive vertical angulation = PID pointing
DOWN to floor/PID
above occlusal plane
• negative vertical angulation = PID point
ing UP to ceiling/PID
below occlusal plane
H
Vortical angulation
• refers to the positioning of the PID in a
horizontal or side-to-side plane
• when tire central ray is directed through the
interproximal contacts of the teeth, correct
horizontal angulation results and open con
tacts on seen the dental image
• incorrect horizontal angulation results in
overlapped contacts (contacts are superim
posed over each other)
ELONGATION resultswhen the vertical angulation is TOO FLAT;teeth look long &
stretched
FORESHORTENINGresults when the verticalangulation is TOOSTEEP; teeth look short
Both photos reprinted from Haring, Joen Iannucci and LauraJansen: Dental Radiography: Principles and Techniques: ThirdEdition. © 2000, with permission from Elsevier.
tech
Identify the cause of this panoramic image error seen below:
chin tipped too far upward
• chin tipped too far downward
' head tipped to one side
copyright © 2013-2014- Dental Decks
RADIOLOGY
Identify the cause of this distorted periapical film seen below:
tech
• film bending
• film creasing
• phalangioma
• double exposure
• movement
Reprinted from Haring,Joen Iannucci andLaura Jansen: DentalRadiography: Principles and Techniques:Third Edition. © 2000,with permission fromElsevier.
58
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RADIOLOGY 58
• chin tipped too far downward
chin tipped too far downward \ /
(see image on reverse side)
• mandibular incisors appear blurred
• loss of detail in anterior apical region
• condyles may not be visible
• results in severe interproximal over
lapping
• occlusal plane has excessive upward
curve
• exaggerated smile line is seen
chin tipped too far forward A
(see image below) ' ^
• hard palate & floor of nasal cavity ap
pear superimposed over maxillary teeth
• maxillary incisors appear blurred
• maxillary incisors appear magnified
• occlusal plane
downward curve
• reverse smile line (frown) is seen
film bending
Film bending
• images appear stretched & distorted
• occurs due to curvature of hard palate
Film creasing
• crease appears as a thin black line
• represents where the emulsion of the film has
cracked
Phalangioma
• the bone of the patient's finger seen on the
image
• results when finger is in front of the receptor
instead of behind it (seen with use of bisecting
technique where patient holds the film— not
recommended)
Light film
• may result from und erexposure— too short
of exposure time, too low kVp or too low mA
Dark film
• may result from overexposure - too long of
exposure time, too high kVp or too high mA
Fogged film - s ^ -
• appears gray & lacks contrast
• occurs when film is exposed to radiation other
than primary beam (e.g., scatter)
• may result from improper safelighting or light
leaks in dark room
All three photos reprinted from Haring, Joen iannucci and Laura Jansen:
Dental Radiography: Principles and Techniques: Third Edition. © 2000,
with permission from Elsevier.
Black film
• exposed to light
Clear film
• film is unexposed
A light film results from
underexposure
a dark film results
from overexposure
a fogged film appears gray and
lacks contrast
tech
A periapical image shows overlapped contacts. This error is cause by:
• vertical angulation is excessive/too steep
• vertical angulation is insufficient/too flat
• incorrect horizontal angulation
• beam not centered over receptor
• poor receptor placement
RADIOLOGY
56copyright © 2013-2014- Dental Decks
tech
Use the two images below to determine the spatial position of the round ob
ject. Following the exposure of image # 1 , the x-ray tubehead was moved and
the beam was directed from a mesial angulation in image #2. Given this in
formation, where is the round object located?
• lingual to the first molar
• buccal to the first molar
• in soft tissue
• in bone
<
c>
Film #1 Film #2
55copyright © 2013-2014- Dental Decks
RADIOLOGY
• incorrect horizontal angulation
Overlapped contacts
• if the central ray is not directed through
the interproximal contacts of the teeth, the
horizontal angulation is incorrect
• incorrect horizontal angulation results in
overlapped contacts seen on the image
Cone-cut
• if the beam is not centered over the recep
tor, a clear unexposed area or cone-cut is
seen on the image
• the PID or "cone" is said to "cut" the image
• a cone-cut may occur with the use of a rect
angular or round PID
• a conecut may occur with or without the
use of a beam alignment device
poor receptor placement
• a periapical image shows the entire tooth
and root, including the apical area and must
be placed to cover those areas
• incorrect periapical receptor placement
may result in absence of apical structures or
a tipped or tilted occlusal plane
• a bite-wing image shows the crowns of both
the maxillary and mandibular teeth, the inter
proximal areas and crestal bone
• incorrect bite-wing receptor placement
may result in absence of teeth or teeth surf-
faces on an image, tipped occlusal plane
Incorrect horizontal angulationresults in overlapped contacts.
If the beam is not centered over the receptor, a cone-cut results& a clear unexposedarea is seen.
Improper placement (if entireroot is not covered) will result inno apices appearing on the image.
Images reprinted from Haring, Joen Iannucci and Laura Jansen: Dental
Radiography: Principles and Techniques: Third Edition. © 2000, with
permission from Elsevier.
lingual to the first molar
Buccal object rule
• a.k.a. tube shift technique
• used to determine an object's spatial po-
sition/buccal-lingual relationship within
the jaws
• two images are obtained, each exposed
with a different angulation
• used to compare the object's position
with respect to a reference point (e.g., root
of a tooth)
Example
• if the PID is moved mesially and the ob
je ct in the second image appears to hav e
moved in the same direction, the object
lies to the lingual
• if the PID is moved mesial ly and the ob
je ct in the second image appea rs to have
moved in the opposite direction, the ob
je ct lies to the bu ccal
• use the acronym SLOB to remember the
buccal object rule
In image #1, notethe location of theobject in referenceto the mesial rootof the first molar.
In image #2, thePID was movedmesially; the ob
ject in referenceto the mesial rootof the first molarhas also movedmesially.
L - O - B RULE
Same = Lingual
extraoral
Identify the radiopaque areas labeled 1 & 2 on the image below.
Reprinted from Iannucci, Joen M. and Howerton, Laura Jansen: Dental Radiography Principles and
Techniques. Fourth edition © 2012 with permission from Elsevier-Saunders.
72copyright ©
2013-2014-
Dental Decks
RADIOLOGY
extraoral
Based on the image below, identify the approximate age of the patient.
Reprinted from Iannucci, Joen M. and Howerton, Laura Jansen: Dental Radiography Principles and Techniques.
Fourth edition © 2012 with permission from Elsevier-Saunders.
73
copyright o 2013-2014- Dental Decks
RADIOLOGY
• answers 1-2 below
Reprinted from Iannucci, joen M. and Howerton, Laura Jansen: Dental Radiography
Principles and Techniques. Fourth edition © 2012 with permission from Elsevier-Saunders.
1. Hoop earring
2. Ghost image of hoop earring
Ghost image
• defined as a radiopaque artifact on a
panoramic image that is produced when a
radiodense object is penetrated twice by the
x-ray beam
• occurs If all metallic or radiodense ob
jects (e.g., eyeglasses, earrings, necklaces,
hairpins, removable partial dentures, com
plete dentures, orthodontic retainers, hear
ing aids, napkin chains) are not removed
before exposure of panoramic receptor
•
obscures diagnostic information
Ghost image appearance
• resembles its real counterpart
• found on the opposite side of the image;
appears indistinct, larger, & highepthan
its actual counterpart
• a ghost image of a hoop earring appears
on the opposite side of the image as a ra-
diopacity that is larger & higher than the
real hoop earring; appears blurred in both
horizontal and vertical directions
• to avoid ghost images, instruct the pa
tient to remove all radiodense objects in the
head-and-neck region prior to exposure of
the panoramic receptor
' < 9 years old
Reprinted from Iannucci, Joen M. and Howerton, Laura Jansen: Dental Radiography Prin
ciples and Techniques. Fourth edition © 2012 with permission from Elsevier-Saunders.
The erupted permanent teeth are highlighted in gray in the charts below. Based on this in
formation, the panoramic film appears to represent a child of < 9 years old.
Permanent teeth
eruption charts
Maxillary
Central incisor
Lateral incisor
Canine
First premolar
Second premolar
First molar
Second
molar
Third molar
Age at eruption
7-8
8-9
11-12
10-12
10-12
6-7
12-13
17-21
Mandibular
Central incisor
Lateral incisor
Canine
First premolar
Second premolar
First molar
Second molar
Third molar
Age at eruption
6-7
7-8
9-10
10-12
11-12
6-7
11-13
17-21
tech
Identify each one of the followin g that is an advan tage of using the parallel
ing technique.
' receptor placement
i comfort
• accuracy
•simplicity
' duplication
59
copyright © 2013-2014- Dental Decks
RADIOLOGY
tech
Identify each one of the following that is a disadvantage of using the bisect
ing technique.
• decreased exposure time
• can be used without a beam alignment device
• distortion
• angulation problems
60copyright © 2013-2014- Dental Decks
RADIOLOGY
Parelling technique
• based on concept of parallelism
• preferred technique for intraoral films
Basic principles
• receptor is placed parallel to the long axis
of the tooth being imaged
• central ray is directed perpendicular to
both the receptor & long axis of the tooth
• a beam alignment device must be used to
keep the receptor parallel to the tooth
• the object-receptor distance must be in
creased to keep the receptor and tooth paral
lel
• the target-receptor distance must be in
creased to make certain the most parallel rays
will be aimed at the tooth and receptor (16"
target-receptor distance)
Long axisol toolh
• accuracy
• simplicity
• duplication
Advantages
• accuracy - image is highly representative
of the actual tooth
• simplicity - simple & easy to learn and use
• duplication - easy to standardize and can be
accurately duplicated when serial images are
needed
Disadvantages
• receptor placement - it may be difficult for
operator to place the beam alignment device
in some patients
• discomfort - the beam alignment device
may cause discomfort
^to Positions of the receptor, tooth and central ray in the paral-
>ft ^% leling technique. The receptor & long axis of the tooth are par-**
<*•
allel. The central ray is perpendicular to the tooth and receptor.An increased target-receptor distance (16 ) is required.
Reprinted from Haring, Joen Iannucci and Laura Jansen: Dental Radiography:
Principles and Techniques: Third Edition. © 2000. with permission from El
sevier.
Bisecting technique
• based on rule of isometry
• technique used for periapicals
Basic principles
• receptor must cover area of interest
• receptor must be placed so 1/8" ex
tending beyond the occlusal or incisal
surfaces
• central ray is directed perpendicular
to the imaginary bisector
• central ray is directed through the
cont act a reas of the teeth
• x-ray beam must be centered over the
receptor so that the entire receptor is ex
posed
• distortion
• angulation problems
Advantages
• can be used withou t a bea m align ment
device and therefore may be more read
ily accepted by patients
• requires a shorter exposure time
Disadvantages
• image distortion (magnification) oc
curs when a short (8") PTD is used
• angulation problems may occur be
cause no beam alignment device is used
resulting in images that are elongated or
foreshortened
Length of image
The image on the receptor is equal to the length of the
tooth when the central ray is perpendicular to the "imag
inary bisector". A short (8 ") target-receptor distance is
required.
Reprinted from Haring, Joen Iannucci and Laura Jansen: Dental Radiography: Princi
ples and Techniques: Third Edition. © 2000, with permission from Elsevier.