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oral radiology > test 2 > Flashcards

test 2 Flashcards

1
Q

what are the 3 types of intraoral images

A
  1. bitewing
  2. periapical
  3. occlusal
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2
Q

how to know when to take xrays on a patient (4)

A
  1. prescribed by the dentist
  2. based on signs symptoms, and risk factors
  3. time intervals between exposures should be based on expert recommendations (selection criteria guidelines)
  4. guidelines for prescribing radiographs document
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3
Q

BITEWINGS

  1. The most ______ exposed image!
  2. Bitewings are taken to examine the ______ of teeth for _______ detection
  3. also taken to ___________ to diagnose and monitor ____________
  4. can be taken with the sensor _____ or _____
  5. When examining for periodontal disease, __________ are preferred
  6. Depending on patient considerations, size ___________ sensors or film may be used (___ is not commonly used).
A
  1. The most FREQUENTLY exposed image!
  2. Bitewings are taken to examine the PROXIMAL SURFACES of teeth for CARIES detection
  3. also taken to EXAMINE ALVEOLAR BONE LEVELS to diagnose and monitor PERIODONTAL DISEASE
  4. can be taken with the sensor HORIZONTALLY or VERTICALLY
  5. When examining for periodontal disease, VERTICAL BITEWINGS are preferred
  6. Depending on patient considerations, size 0, 1, 2, OR 3 sensors or film may be used (3 is not commonly used).
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4
Q

RECEPTOR SIZE 0

  1. recommended for use with THESE patients
  2. number and orientation of image receptor
A
  1. child with primary dentition
  2. 2 horizontal posterior
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5
Q

RECEPTOR SIZE 1

  1. recommended for use with THESE patients
  2. number and orientation of image receptor
A
    • child with primary or mixed dentition
    • adult for caries detection or the presence of periodontal disease
    • 2 horizontal posterior
    • 3 or 4 vertical anterior
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6
Q

RECEPTOR SIZE 2

  1. recommended for use with THESE patients
  2. number and orientation of image receptor
A
    • child with mixed dentition, PRIOR to eruption of permanent second molars
    • adolescence after the eruption of the permanent second molars
    • adult
    • adult with periodontal disease
    • 2 horizontal posterior
    • 4 horizontal posterior
    • 4 horizontal posterior
    • 4 vertical posterior
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7
Q

RECEPTOR SIZE 3

  1. recommended for use with THESE patients
  2. number and orientation of image receptor
A
    • adolescent after the eruption of the permanent second molars
    • adult
    • 2 horizontal posterior
    • 2 horizontal posterior
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8
Q

WHY ARE BITEWINGS THE MOST FREQUENTLY EXPOSED IMAGE?

We cannot examine the _________ of teeth _____

Nearly impossible on _____ of _____ teeth

bitewings are valuable in revealing ______

A

We cannot examine the PROXIMAL SURFACE of teeth CLINICALLY!

Nearly impossible on BROAD SURFACES of POSTERIOR teeth

Bitewings are valuable in revealing INCIPIENT DECAY

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9
Q

HORIZONTAL VS VERTICAL BITEWING EXAM

  1. Adults with caries risk or meeting selection criteria guidelines; a set of __ posterior, _______ bitewings is preferred:

a. One _____ image and one _____ image on the right and left sides using a size ___ sensor

  1. Adults with periodontal disease or meeting selection criteria, a set of _ _________ posterior bitewings or _ _______ posterior bitewings with 3 or 4 _______ vertical bitewings (total of 7 or 8)

a. Size __ for the posterior bitewings and size ___ for the anterior bitewings

A
  1. Adults with caries risk or meeting selection criteria guidelines; a set of 4 posterior, HORIZONTAL bitewings is preferred:

a. One MOLAR image and one PREMOLAR image on the right and left sides using a size 2 sensor

  1. Adults with periodontal disease or meeting selection criteria, a set of 4 VERTICAL posterior bitewings or 4 VERTICAL posterior bitewings with 3 or 4 ANTERIOR vertical bitewings (total of 7 or 8)

a. Size 2 for the posterior bitewings and size 1 for the anterior bitewings

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10
Q

PREPARE THE EQUIPMENT

  1. ___, _____, and ____ x-ray unit (we use a
    ________)
  2. Assemble _________, _________, ________, etc.

3.Set/check exposure factors (__, ___, ___)
a. Reduce exposure time for _________,
and _________
b. Anterior exposures require ______ radiation
than posterior exposures

A
  1. CLEAN, DISINFECT, and COVER x-ray unit (we use a PLASTIC BAG)
  2. Assemble IMAGE RECEPTOR, IMAGE RECEPTOR HOLDERS, AND COTTON ROLSS, etc.
  3. Set/check exposure factors (mA, kV (kVp), time)
    a. Reduce exposure time for CHILDREN,
    EDENTULOUS AREAS
    b. Anterior exposures require LESS radiation
    than posterior exposures
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11
Q

PREPARE THE PATIENT

  1. Explain the ________ to the client.
  2. Ask client to remove _______, _______, ________, __________, etc.
  3. Adjust the chair to a comfortable _______
  4. Adjust the patient headrest:
    * ________ perpendicular to the ____
    * ________ parallel to the ____
  5. Protect patient with ________ and _____
A
  1. Explain the PROCEDURE to the client.
  2. Ask client to remove EYEGLASSES, SAFETY GLASSES, REMOVEABLE DENTURES, RETAINERS, ETC.
  3. Adjust the chair to a comfortable WORKING HEIGHT
  4. Adjust the patient headrest:
    * MIDSAGGITAL PLANE perpendicular to the FLOOR
    * OCCLUSAL PLANE parallel to the FLOOR
  5. Protect patient with A LEAD SHIELD AND A THYROID COLLAR
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12
Q

BEFORE YOU BEGIN EXPOSING IMAGES:

Have ______ and _____ prepared.

Anticipate the ___________.

Try to begin with the ______ placement

complete all ________ images first (_______).

complete all _______ images on one side before moving to the other side.

Be ________ to avoid errors or ________

A

Have IMAGE RECEPTORS and HOLDERS prepared.

Anticipate the PATIENTS NEEDS

Try to begin with the EASIEST placement

complete all ANTERIOR images first (PREMOLAR).

complete all POSTERIOR images on one side before moving to the other side.

Be SYSTEMATIC to avoid errors or ACCIDENTLY EXPOSING AN IMAGE TWICE

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13
Q

what are the 4 steps to obtaining bitewings

A
  1. packet placement or sensor placement
  2. vertical angulation
  3. horizontal angulation
  4. centering
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14
Q

YOUR IMAGE RECEPTOR PLACEMENT IS TO CAPTURE AN AREA OF INTEREST

Each bitewing radiograph has a specific placement to capture the teeth of interest.

For molar bitewings, the area of interest is: _________

For the premolar bitewing, the area of interest is: _____________

A

For molar bitewings, the area of interest is: BETWEEN THE FIRST AND SECOND MOLAR

For the premolar bitewing, the area of interest is: BETWEEN THE FIRST AND SECOND PREMOLAR

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15
Q

STEP ONE: PLACE THE SENSOR CORRECTLY

Place image receptor ______ to ___________

For a premolar image, place the anterior edge of the image receptor to capture the ___________ portion of the _____

for a molar image, place the anterior edge of the image receptor to capture the _______ portion of the __________

To achieve this, we need to check the patient’s
_______

place image receptor near the ________ of the ______

A

Place image receptor PARALLEL to INTERPROXIMAL AREA OF INTERST

For a PREMOLAR image, place the anterior edge of the image receptor to capture the DISTAL portion of the MOST MESIAL CANINE

for a MOLAR image, place the anterior edge of the image receptor to capture the DISTAL portion of the SECOND PREMOLAR

To achieve this, we need to check the patient’s
OCCLUSION

place image receptor near the CENTER of the ORAL CAVITY

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16
Q

3 types of occlusion

A
  1. mesoganthic
  2. prognathic
  3. retrognathic
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17
Q

what teeth should be imaged for a premolar BW

A
  • distal portion of max and mand canines
  • 1st and 2nd premolars
  • mesial portion of 1st molar
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18
Q

what teeth should be imaged for a molar BW

A
  • distal portion of max and mand 2nd premolars
  • 1st, 2nd, and 3rd molars if present
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19
Q

for anterior bitewings (_________), focus on ________

how should a central incisor BW look

how should a canine BW look

A
  1. for anterior bitewings (VERTICAL), focus on CENTERING THE TOOTH ON THE IMAGE RECEPTOR
  2. center the image receptor behind the left and right central AND lateral incisors
  3. center the film packet or image receptor to line up behind the canine; include the distal half of the lateral incisor and the mesial half of the first premolar
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20
Q

VERTICAL ANGULATION (bitewings)

  • this is the _______ plane of the central xray beam
  • when free handing, use ____ vertical angulation
A
  • this is the UP/DOWN plane of the central xray beam
  • when free handing, use 10+ vertical angulation
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21
Q

HORIZONTAL ANGULATION (correct horizontal angulation for bitewings is CRITICAL)

  • this is the ____ plane of the central xray beam
  • first, position the image receptor _____ to teeth of interest
  • then, direct central ray _____ to the image receptor through the ______
A
  • this is the SIDE/SIDE plane of the central xray beam
  • first, position the image receptor PARALLEL to teeth of interest
  • then, direct central ray PERPENDICULAR to the image receptor through the CONTACTS
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22
Q

CENTER THE XRAY BEAM

  • Center means, ensuring the ___ and ________ covers all parts of the image receptor.
  • Have the patient _______ and position the PID so the __________ is the center of the ______ of the PID circle
A
  • Center means, ensuring the PID and CENTRAL RAY covers all parts of the image receptor.
  • Have the patient SMILE and position the PID so the BITE TAB is in the center of the OPEN FACE of the PID circle
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23
Q

If we have not performed one of our steps correctly, we will see _____ in our technique.

Pointing out these errors and understanding how to correct them is part of _______ our images!

Depending on how bad of an error we made we classify errors in technique as a ______ error or a _____ error

A

If we have not performed one of our steps correctly, we will see ERRORS in our technique.

Pointing out these errors and understanding how to correct them is part of INTERPRETING our images!

Depending on how bad of an error we made we classify errors in technique as a TECHNICAL error or a RETAKE error

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24
Q

what is the difference between a technique and retake error

A

technique error is small and does not result in client re- exposure.

A retake means we have a big error that affects the diagnostic quality of the image and results in client re-exposure

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25
Q

what happens if we do not place our image receptor correctly

A
  • too far anterior will show more of the anterior teeth
  • too far posterior will show more of the posterior teeth
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26
Q

HOW TO CORRECT PLACEMENT ERRORS

If you are not imaging the most ANTERIOR tooth in the image (i.e. the distal portion of the canine, distal portion of the 2nd premolar), move the image receptor __________

If you are imaging TOO MUCH of the most anterior tooth in the image (especially if it is affecting your horizontal angulation), move the image receptor __________.

If taking an anterior bitewing, if the tooth/teeth of interest are not _________, move the PID to the ________ accordingly to correct.

A

If you are not imaging the most ANTERIOR tooth in the image (i.e. the distal portion of the canine, distal portion of the 2nd premolar), move the image receptor ANTERIORLY

If you are imaging TOO MUCH of the most anterior tooth in the image (especially if it is affecting your horizontal angulation), move the image receptor POSTERIORLY.

If taking an anterior bitewing, if the tooth/teeth of interest are not CENTERED, move the PID to the LEFT/RIGHT accordingly to correct.

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27
Q

WHEN WOULD WE RE-EXPOSE THE CLIENT (placement error)

A
  • when the distal portion of the canine or distal portion of premolar are NOT imaged in one arch or ARE NOT SEEN IN ANY OTHER IMAGE IN THE SET OF BITEWINGS
  • for a practical in lab: if we do not image the needed distal in just ONE arch, REEXPOSE
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28
Q

what happens if our vertical angulation is not correct (bitewings)

A
  • excessive: seeing too much of the maxillary arch
  • inadequate: seeing too much of the mandibular arch
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29
Q

how to correct vertical angulation

A
  • To correct EXCESSIVE vertical angulation: DECREASE your vertical angulation
    (move the PID closer to zero) (raise it UPPPP)
  • To correct INADEQUATE vertical angulation: INCREASE your vertical angulation (move the PID more positively) (move it DOWNN)
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30
Q

when would we re-expose a client (vertical angulation)

A

TECHNIQUE ERROR in vertical angulation: results in UNEQUAL distribution of the arches

RE-EXPOSURE: occurs if you CANNOT SEE the alveolar bone in one arch COMPLETLY.

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31
Q

what happens if our horizontal angulation is incorrect

A
  • too far mesial: overlaps worsens in the distal/posterior
  • too far distal: overlap worsens in the mesial/anterior
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32
Q

how to correct horizontal angulation

A

To correct the PID being too far MESIAL: check that you have placed the image receptor
PARALLEL to the teeth of interest, and then move the PID to the DISTAL.

To correct the PID being too far DISTAL: check that you have placed the image receptor parallel to the teeth of interest, and then move
the PID towards the MESIAL

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33
Q

technique error vs retake error in horizontal angulation

A

TECHNIQUE ERROR: overlap between the contacts in the teeth of interest is SLIGHT in
BOTH arches and does NOT overlap past the DEJ.

RE-EXPOSURE: occurs when overlap in the teeth of interest is PAST the DEJ in BOTH arches or PAST the DEJ in ONE arch

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34
Q

what happens if centering is not correct

A
  • cone cuts

(clear/blank areas where NO x-rays reached the image receptor)

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35
Q

how to correct centering for bitewings

when do we re-expose

A
  1. more the PID in the DIRECTION OF THE CONECUT (PID needs to cover the entire sensor)
    • TECHNIQUE ERROR: conecuts ANYWHERE in the image
    • RETAKE ERROR: when conecut is IN the area of interest
36
Q

PERIAPICAL IMAGES

Peri = ______, Apex = ______

Exposed to image ______ and _______

Can be taken as a _________ exam or can be taken in combination with ____ in a series (____)

A

peri = AROUND; apex = ROOT END

exposed to image ROOT APICIES and ALVEOLAR BONE

can be taken as a STAND-ALONE exam or can be taken in combination with BITEWINGS in a series (FMS/FMX)

37
Q

WHAT SIZE IMAGE RECEPTOR IS USED FOR PA’s

size 1 is used for _______ : this include max and mand ______ and mandibular ______ PA

size 2 are used for _______ AND _______ : this includes max ________ and max __________

A

size 1 is used for ANTERIOR PA’s ON AN ADULT: this include max and mand CANINES and mandibular CENTRALS

size 2 are used for POSTERIOR PA’s AND MAX CENTRAL INCISOR : this includes max MOLAR AND PREMOLAR and max CENTRALS

38
Q

HOW SHOULD THE IMAGE RECEPTOR BE ORIENTED

for anterior

for posterior

A

anterior PA’s: the sensor is placed VERTICALLY intraorally

posterior: the sensor is placed HORIZONTALLY intraorally

39
Q

what are the reasons to take a PA (6)

A
  1. apical pathology
  2. fractures
  3. large carious lesions
  4. developmental anomalies
  5. unexplained pain or bleeding
  6. extensive perio (angulation must be precise and vertical bitewings are PREFERRED)
40
Q

all anterior exposures use a size one EXECPT

A

maxillary central incisors (size 2)

41
Q

what is the sequence for a FMS (14 steps)

A
  1. 3 maxillary anterior PAs
  2. 3 mandibular anterior PAs
  3. right max posterior premolar PA
  4. right max posterior molar PA
  5. Left mand posterior premolar PA
  6. left mand posterior molar PA
  7. right mand posterior premolar PA
  8. right mand posterior molar PA
  9. left max posterior premolar PA
  10. left max posterior molar PA
  11. right premolar BW
  12. right molar BW
  13. left premolar BW
  14. left molar BW
42
Q

what are the 2 techniques for exposing PAs

A

paralleling and bisecting

43
Q

the __________ principles are important in producing a ________ image when you are using ______ technique

The ____ of these you satisfy, the less ______ and _____ to your image:

A

the SHADOW CAST principles are important in producing a DIAGNOSTIC QUALITY image when you are using EITHER technique

The MORE of these you satisfy, the LESS MAGNIFICATION and DISTORTION to your image

44
Q

what are the shadow casting principles (5)

A
  1. SMALL FOCAL SPOT (TARGET)
    - focal spot is located inside the tube housing in the xray unit
  2. LONG FOCAL SPOT/TARGET TO TOOTH DISTANCE
    - use the longest PID possible (16 in)
  3. SHORT TOOTH TO IMAGE RECEPTOR DISTANCE
    - place the sensor close to the tooth when the patient bites down
  4. PARALLEL RELATIONSHIP BETWEEN THE TOOTH AND THE IMAGE RECEPTOR
    - place the sensor parallel to the teeth of interest
  5. PERPENDICULAR RELATIONSHIP BETWEEN THE XRAY BEAM, TOOTH, AND IMAGE RECEPTOR
    - direct your xray beam at a right angle to the teeth of interest and image receptor
45
Q

which technique meets MORE shadow cast principles and is considered the gold standard technique

A
  • paralleling
46
Q

The two basic principles of the paralleling technique meet the last two shadow cast principles; what are they?

A
  1. the image receptor is placed parallel to the long axis of the tooth
  2. the central ray is directed perpendicular to the image receptor and the long axis of the tooth
47
Q

what are the 3 advantages to the paralleling technique

A
  1. satisfies more shadow cast principles
  2. yields radiographs with minimal image distortion
  3. minimizes the superimposition of adjacent oral structures
48
Q

what are 3 disadvantages to the paralleling technique

A
  1. A parallel relationship between the image receptor and tooth may be difficult to achieve on some clients
  2. Paralleling requires a long PID to compensate for the placement of the image receptor being further away from the tooth to achieve a parallel relationship between tooth and film/image receptor
  3. requires the use of a image receptor holder
49
Q

describe the image receptor holder that is designed specifically for paralleling

A
  • long biteblocks
  • L-shaped backing
50
Q

WHAT MAKES A PA IMAGE OF DIAGNOSTIC QUALITY

The PA must have the image receptor positioned ________ for posterior PAs and _________ for anterior PAs.

A PA needs to image the _______ plus __mm of _______ beyond the apex.

A PA image needs about _____ in. beyond the _____ edge.

A
  1. The PA must have the image receptor positioned HORIZONTALLY for POSTERIOR PAs and VERTICALLY for ANTERIOR PAs.
  2. A PA needs to image the ENTIRE TOOTH plus 2mm of SUPPORTING BONE beyond the apex.
  3. A PA image needs about 1/4th in. beyond the INCISAL/OCCLUSAL edge.
51
Q

what are the 4 steps to exposing PAs

A
  1. placement
  2. vertical angulation
  3. horizontal angulation
  4. centering
52
Q

what is the patient positioning for PAs

A
  1. occlusal place parallel to floor
  2. midsagittal plane perpendicular to floor

SAME AS BITEWINGS

53
Q

PA PLACEMENT

What is important about placement when paralleling is that you are placing the sensor at a ______ angle to the teeth of interest and the patient is biting ________ on the biteblock.

EXECPTION – ______________

A

What is important about placement when paralleling is that you are placing the sensor at a PARALLEL angle to the teeth of interest and the patient is biting FAR AWAY on the biteblock.

EXCEPTION: MANDIBULAR PREMOLAR AND MOLAR IMAGES.
- for these images you can place the sensor CLOSER to the teeth and still remain parallel

54
Q

VERTICAL ANGULATION

  • vertical angulation is set by placing the PID ________ to the tooth and image receptor
A
  • vertical angulation is set by placing the PID PERPENDICULAR to the tooth and image receptor
55
Q

vertical angulation errors in paralleing and how to fix it

A

excessive: cut of incisal edge. How to correct: DECREASE THE VERTICAL ANGULATION

inadequate: cuts off the apex. how to correct: INCREASE THE VA

56
Q

HORIZONTAL ANGULATION FOR PA’s

For molar posterior PAs, you want to direct your central rays perpendicular to the image receptor through the _____________

For premolar posterior PAs, you want to direct your central rays perpendicular to the image receptor through the _____________

For central incisor PAs (maxillary or mandibular) you want to direct your central rays perpendicular to the image receptor through the ____________

For canine PAs, you want to direct your central rays perpendicular to the image receptor at the ___________

A

For molar posterior PAs, you want to direct your central rays perpendicular to the image receptor through the FIRST AND SECOND MOLARS

For premolar posterior PAs, you want to direct your central rays perpendicular to the image receptor through the FIRST AND SECOND PREMOLARS

For central incisor PAs (MAX OR MAND) you want to direct your central rays perpendicular to the image receptor through the LEFT AND RIGHT CENTRAL INCISORS (8 and 9 or 24 and 25).

For canine PAs, you want to direct your central rays perpendicular to the image receptor at the CENTER OF THE CANINE

57
Q

CENTERING FOR PA’s

A
  • center the image receptor within the path of the xray beam
  • direct the central rays at the CENTER of the image receptor
58
Q

the bisecting technique is the _______ technique

what is the main difference between bisecting and paralleling

central rays are directed where

A

the bisecting technique is the SUPPLEMENTAL technique

  • the image receptor IS NOT PARALLEL to the teeth or the image receptor
  • central rays are directed PERPENDICULAR to the IMAGINARY BISECTOR
59
Q

what two shadow casting principles does the bisecting technique follow

A
  1. small focal spot/target
  2. short tooth to image receptor distance
60
Q

what are the advantages to the bisecting technique

what are the disadvantages

A
  1. film receptor may be easier to achieve in certain clients such as:
    - low palatal vault
    - tori present
    - exaggerated gag reflex
    - children
    - edentulous areas
    • satisfies LESS shadow cast principles
    • greater image magnification and distortion
    • may increase client radiation exposure due to use of short PID
61
Q

describe how the placement for bisecting is different from paralleling

what is an exception in this technique

A
  • you want to place the sensor as close to the teeth as possible
  • EXCEPTION: mandibular premolar and molar region
62
Q

how is vertical angulation different in the bisecting technique.

how do the two errors look

A
  1. When bisecting, direct central rays PERPENDICUALR to the IMAGINARY BISECTOR
  • EXCESSIVE VERTICAL ANGULATION: foreshortened teeth/image
  • INADEQUATE VERTICAL ANGULATION: elongated teeth/image
63
Q

what causes foreshortened teeth, how is it corrected

what causes elongated teeth, how is it corrected

A
  1. EXCESSIVE VA; correct by DECREASING THE VA
  2. INADEQUATE VA: correct by INCREASING THE VA
64
Q

Foreshortening/elongation is a ________ error. This means, if you are attempting to use the paralleling technique and you notice that your image/teeth appear foreshortened, you were inadvertently using the _______ technique. You will only see this error when you are ________.

A

Foreshortening/elongation is a BISECTING error. This means, if you are attempting to use the paralleling technique and you notice that your image/teeth appear foreshortened, you were inadvertently using the BISECTING technique. You will only see this error when you are BISECTING.

65
Q

what is the suggested average vertical angulations when utilizing the BISECTING technique

max incisors
max canines
max premolars
max molars

mand incisors
mand canines
mand premolars
mand molars

A

max incisors: +40
max canines: +45
max premolars: +30
max molars: +20

mand incisors: -15
mand canines: -20
mand premolars: -10
mand molars: -5

66
Q

what makes an image acceptable diagnostic quality? (3)

A
  1. Structures recorded are close to
    NATURAL SIZE and SHAPE as the patient’s oral
    anatomy
  2. Examined area is imaged completely
    with enough surrounding tissue
  3. Radiograph is free of errors and has
    proper density, contrast, and definition.
67
Q

define radiopaque and radiolucent

A

RADIOLUCENT: dark gray/black; structures are EASILY penetrated by x-rays

RADIOPAQUE: lighter gray/white/clear; structures are NOT easily penetrated by xrays

68
Q

IMAGE DENSITY

Refers to the overall _______ of the image

LOW DENSITY = ______

HIGH DENSITY = _______

dense material allows ___________ penetration through to the image receptor

A

Refers to the overall DARKNESS of the image

LOW DENSITY = LIGHTER IMAGE

HIGH DENSITY = DARKER IMAGE

dense material allows LESS RADIATION penetration through to the image receptor

69
Q

IMAGE CONTRAST

refers to the ________ of the image

high contrast =

low contrast =

A

refers to the DIFFERENT DENSITIES of the image/ DIFFERENT SHADES OF GRAY

high contrast = black and white with LITTLE shades of gray in between. SHORT SCALE

low contrast = black and white with MANY shades of gray in between. LONG SCALE.

70
Q

IMAGE SHARPNESS

Refers to _______ and _________ of the structures on a radiograph

Unsharpness/blurriness may be caused by ________, ________ or _______ during exposure

Sharpness can be affected by _______

A

Refers to detail and clarity of the outline of the
structures on a radiograph

Unsharpness/blurriness may be caused by MOVEMENT OF THE PATIENT, IMAGE RECEPTOR, OR TUBE HEAD during exposure

Sharpness can be affected by SEVERAL OTHER FACTORS

71
Q

what are 4 different factors that affect the DENSITY and CONTRAST of the radiographic image

A
  1. subject factors
  2. exposure factors
  3. image receptor factors
  4. geometric factors
72
Q

EFFECTS OF SUBJECT FACTORS/THICKNESS OF STRUCTURES

Refers to the ________ being imaged.

Regions with tissues of different densities/thickness = ___________

Regions with tissues of similar density/thickness = _____________

_______ factors affect density based on the thickness of the structures being imaged: more dense areas will allow __________

A

Refers to the TYPES OF TISSUES being imaged.

Regions with tissues of different densities/thickness = AN INCREASE IN CONTRAST BETWEEN THE TISSUES (LESS SHADES OF GRAY IN BETWEEN)

Regions with tissues of similar density/thickness = A DECREASE IN CONTRAST (MANY SHADES OF GRAY IN BETWEEN DIFFERENT AREAS)

SUBJECT factors affect density based on the thickness of the structures being imaged: more dense areas will allow LESS X-RAYS TO PENETRATE

73
Q

HOW DO THE FOLLOWING EXPOSURE FACTORS EFFECT FILM DENSITY

increasing the mA
decreasing the mA
increasing exposure time
decreasing exposure time
increasing kVp
decreasing kVp

A

increasing the mA: INCREASES THE DENSITY

decreasing the mA: DECREASES THE DENSITY

increasing exposure time: INCREASES THE DENSITY

decreasing exposure time: DECREASES THE DENSITY

increasing kVp: INCREASES THE DENSITY

decreasing kVp: DECREASES THE DENSITY

74
Q

t/f when any exposure factor is increased/decreased, the other exposure factors can remain the same to maintain optimum image density.

A

FALSE: when any exposure factor is increased/decreased, ONE OR MORE OF THE OTHER FACTORS MUST BE ADJUSTED to maintain optimum image density.

75
Q

varying kVp primarily affects the _________, but it will secondarily affect the _______.

increase the kVp for _________; decrease the kvp for ________

A

varying kVp primarily affects the CONTRAST, but it will secondarily affect the DENSITY.

increase the kVp for LESS CONTRAST; decrease the kvp for MORE CONTRAST

76
Q

MILLIAMPERE-SECONDS

mA and time regulate the _______ and have the same effect on _______.

what are they combined to

what is the equation for MAS

what is the calculation for

EXAMPLE:
10 mA at 0.3 seconds exposure = _____
15 mA at 0.2 seconds exposure = _____

A

MA and TIME regulate the NUMBER OF XRAYS GENENERATED and have the same effect on DENSITY.

COMBINED INTO mAs (milliampere/seconds)

equation: MILLIAMPERES X EXPOSURE TIME (SECONDS) = MILLIAMPERE-SECONDS

DETERMINES TOTAL RADIATION GENERATED

EXAMPLE:
10 mA at 0.3 seconds exposure = 3.0 mAs
15 mA at 0.2 seconds exposure = 3.0 mAs

77
Q

MAS EXAMPLE

Using an mA setting of 10 with an exposure time of .5 = 5 milliampere - seconds. If we
increase the mA setting to 15, to obtain an image of equal density, how many SECONDS of exposure time should be set?

A

0.3 seconds

78
Q

kvp and contrast are _____ related

increase kvp =
decrease kvp =

A

kvp and contrast are INVERSLY RELATED

increase kvp = decreased contrast

decrease kvp = increased contrast

79
Q

what is the KILOVOLTAGE PEAK RULE

A
  • when the kVp is INCREASED by 15, DIVIDE the exposure time by 2
  • when the kVp is DECREASED by 15, MULTIPLY the exposure time by 2
80
Q

what is image receptor SPEED based on

A
  1. crystal/pixel size: LARGER = FASTER
  2. number of crystals/pixels: MORE = FASTER
81
Q

FILM SPEED

Given the SAME settings, a D speed film would appear ______ than an F speed film because it requires ________ to get an image of equal density

When CHANGING film speed, adjust _________.

When switching from “D” speed to “E” speed film, _______ exposure time by ___%.

When switching from “E” speed to “F” speed film, ________ exposure time by ___%.

A

Given the SAME settings, a D speed film would appear LIGHTER (LESS DENSE) than an F speed film because it requires MORE RADIATION to get an image of equal density

When CHANGING film speed, adjust THE EXPOSURE TIME.

When switching from “D” speed to “E” speed film, DECREASE exposure time by 50%.

When switching from “E” speed to “F” speed film, DECREASE exposure time by 10%.

82
Q

INVERSE SQUARE LAW

  1. as the distance from the source of radiation INCREASES:
    - the beam diameter:
    - the beam intensity:
  2. the _____ will decrease by _______
  3. when changing the ________ we must alter the ______ to achieve equal image density
A
  1. as the distance from the source of radiation INCREASES:
    - the beam diameter INCREASES
    - the beam intensity DECREASES
  2. The INTENSITY will DECREASE by the SQUARE OF THE DISTANCE
  3. when changing the DISTANCE (PID LENGTH) we must alter the IMPULSE/TIME to achieve equal image density
  4. 6 ft away, 45 degree angle
83
Q

if a radiographer was standing 3 ft away from the source, how much more radiation would he be exposed to compared to someone standing 6 ft away

A

4x more

84
Q

INVERSE SQUARE LAW

As the distance from the source of radiation
______ the intensity of the radiation ________ and the beam diameter _______.

As the distance from the source of radiation _______ the intensity of the radiation _______ and the beam diameter _________

A

As the distance from the source of radiation
INCREASES the intensity of the radiation DECREASES and the beam diameter INCREASES.

As the distance from the source of radiation DECREASES the intensity of the radiation INCREASES and the beam diameter DECREASES

85
Q
  1. With an 8” PID, an exposure intensity is 200 mSv. The exposure time is 4s and all other factors constant, what would the intensity be if a 16” PID is used?
  2. If you wanted to keep the exposure intensity at 200mSv with this new 16in PID, what should you do? Find the new exposure time.
A
  1. USE: original intensity / new intensity = new distance ^2 / original distance ^2

200 / x = 16^2 / 8^2

200/x = 256/64

256x = 12,800

x = 50

  • THE DISTANCE WAS INCREASED BY 2 AND THE INTENSITY WAS DECREASED BY 4
  1. USE: original exposure time / new exposure time = original distance ^2 / new distance ^2

4 / x = 8^2 / 16^2

4 / x = 64 / 256

64x = 1024

x = 16

  • THE DISTANCE WAS INCREASED BY 2 AND THE EXPOSURE TIME WAS INCREASED BY 4
86
Q

IMAGE SHARPNESS

what is it

what causes an UNSHARP image

A
  1. detail and clarity
  2. image receptor movement, client movement, tube head movement, large focal spot, long object to image receptor distance, short target to image receptor distance, large silver halide crystals with film
87
Q

REVIEW THE ADA GUIDELINES FOR PRESCRIBING RADIOGRAPHS

A

REVIEW THE ADA GUIDELINES FOR PRESCRIBING RADIOGRAPHS

oral radiology (7 decks)

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