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4 Radiology > Panoramic radiography > Flashcards

Panoramic radiography Flashcards

1
Q

what is the most common extra-oral radiograph in dentistry?

A

panoramic radiography

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2
Q

what is tomography?

A

allows slices of the subject to be viewed separately

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3
Q

what are the 2 types of tomography?

A

Conventional
Computed

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4
Q

what is the difference between conventional and computed tomography?

A

conventional is one slice
computed is multiples slices

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5
Q

what is panoramic radiography?

A

Form of conventional tomography where it captures and displays the curved shape of the jaws as a 2D image

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6
Q

panoramic radiography technique

Patient stands in ? of machine

X-ray source ? patient

Receptor ? patient

Both rotate at the same time ?* (they remain ? each other)

Whole thing takes ? so ? affects image greatly

A

middle

behind

in front of

180*
opposite

14 seconds
movement

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7
Q

modified version of linear tomography

X-ray source and receptor move in ? directions

Structures in the focal slice remain projected on the same point on the receptor and appear ?

Structures outside the focal slice are continually projected on different parts of the receptor and appear ?

the focal trough in panoramic radiographs are ?

A

opposite

clear

blurry

the jaws

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8
Q

panoramic radiography captures the full thickness of the jaw but the focal trough is a thin band where the image is clearest

as you go bucally or lingually to the focal trough the image quality ?

A

decreases

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9
Q

where is the focal trough thinner? why? impact?

A

the incisor region due to speed of rotation -> common for incisors to be blurry

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10
Q

what is a limitation of panoramic radiography (focal trough)?

A

ectopic teeth may be far out of the focal trough so appear missing

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11
Q

what is the default choice for panoramic radiography?

A

orthogonal programme

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12
Q

what does orthogonal programme aim to do? how?

A

provide an optimal view of the dentition

	○ X-ray angulation changed to more orthogonal (90* to teeth)
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13
Q

advantages of orthogonal programme panoramic radiographs? 3

A

Reduced overlap -> proximal caries

Improved view of pre molars

Interdental periodontal bone levels represented more accurately

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14
Q

disadvantages of orthogonal programme panoramic radiographs? 2

A

Distorts other structures
Narrower field of view -> may miss condyles

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15
Q

describe the magnification within the focal trough?

A

image is magnified 25%

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16
Q

describe the magnification of structures lingual to the focal trough

A

magnified more

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17
Q

describe the magnification of structures buccal to the focal trough

A

magnified less

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18
Q

describe the distortion of structures within the focal trough

A

not distorted as horizontal magnification matches vertical

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19
Q

describe the distortion of teeth positioned lingual to the focal trough

A

appear wider

as closer to x-ray source

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20
Q

describe the distortion of teeth positioned buccal to the focal trough

A

appear narrower

further from x-ray source and closer to receptor

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21
Q

what is field limitation?

A

instead of doing a full size panoramic radiograph, when appropriate reduce the area to reduce the dose

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22
Q

what are the 4 main components of a panoramic machine?

A

X-ray tube head

Receptor

Control panel

Patient-positioning apparatus

23
Q

what are the 2 patient-positioning aparatus?

A

bite peg

light beam markers

24
Q

what does the bite peg do (patient positioning)

A

ensures edge-to-edge occlusion and both arches are in the focal trough plane

25
Q

when is it impossible to get edge to edge occlusion on the bite peg?

A

class III occlusion

26
Q

Patient too far forwards -> incisors appear ?

A

narrower as buccal to focal trough

27
Q

Patient too far backwards -> incisors appear ?

A

wider as lingual to focal trough

28
Q

here the incisors appear narrow, why is this?

A

patient too far forwards

29
Q

here the incisors appear wider, why is this?

A

patient too far back

30
Q

light beam markers

the horizontal line matches what?

A

Frankfort plane (infraorbital margin -> EAM)

31
Q

beam markers

if the chin is down (frankfort plane above horizontal line) what happens to the occlusal plane?

A

smiling occlusal plane

32
Q

beam markers

if the chin is up (frankfort plane below horizontal line) what happens to the occlusal plane?

A

flat occlusal plane

33
Q

look at this example where the Frankfort plane is horizontal

A
34
Q

what has caused this wrong occlusal plane?

A

smiling occlusal plane
chin down
Frankfort plane below horizontal line

35
Q

what has caused this wrong occlusal plane?

A

flat occlusal plane
chin up
Frankfrot plane above horizontal line

36
Q

beam markers for patient positioning

Vertical midline matches?

A

mid-sagittal plane

37
Q

beam markers for patient positioning

if the mid sagittal plane is not centred what happens?

A

distortion of one/both sides

38
Q

beam markers for patient positioning

if the mid-sagital plane is not vertical what happens?

A

distortion and occlusal plane cant

39
Q

beam markers for patient positioning

canine lines match what?

A

maxillary canines

40
Q

what causes this excessive cervical spine shadow?

A

patient slumped

41
Q

preparation for panoramic radiographs 3

A

Remove metal foreign bodies from head and neck e.g. piercings

Keep patient as upright as possible
- Patient slumped -> excessive cervical spine shadow

Advise patient
- Tongue to roof of mouth
- Stand still
- Don’t talk or swallow

42
Q

what causes part of the image to be cut out?

A

sharp horizontal movement

43
Q

what causes a smeared image?

A

slow horizontal movement

44
Q

what causes Zigzag of mandible and teeth?

A

vertical movement of mandible

45
Q

what causes this?

A

patient movement

46
Q

what caused this air gap?

A

tongue not to palate

47
Q

what has caused the left soft palate to be wiggly?

A

tongue movement

48
Q

what has caused this zigzag pattern?

A

vertical mandible movement

49
Q

what has caused this smear?

A

patient moving

50
Q

what has caused part of the image to be cut out?

A

Brief sharp horizontal movement

51
Q

are lead aprons required in dental radiography?

A

no

52
Q

what is a quality standards checklist?

A

list of things to check on panoramic radiographic image

53
Q

look at this quality standards checklist

A

4 Radiology (19 decks)

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