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Flashcards in panoramic radiography Deck (27)
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1
Q

what is panoramic radiography

A

shows us a picture of the entire dentition - unobstructed view if every region in every direction - dynamic movement

2
Q

what is the greyscale is dependant on

A

the degree of absorption

3
Q

what is tomography

A

coordinated source of movement of the image receptor and the tube

4
Q

what does tomography generate

A

an in focus slice of anatomy

5
Q

what does the technique produce

A

a curved in focus slice called the focal trough

6
Q

what do we want the dental trough to coincide with

A

the entire dentition

7
Q

what is the x ray source and the tube called

A

the gantry

8
Q

what happens to the image outside the focal trough

A

they are blurry

9
Q

what is the angle between the x ray source and the tube

A

8 degree angulation

10
Q

how are ghost images produced

A

anything between the x ray source and the centre of rotation

11
Q

characteristics of ghost imaged compared to the real image

A

larger
higher
on the opposite side
blurred (more blurred vertically than horizontally)

12
Q

why is the ghost image larger

A

due to beam convergence

13
Q

why is the ghost image higher

A

due to the beam angulation

14
Q

how dow we get a crisp beam

A

with less divergence of the x ray beam

15
Q

when is the image in focus

A

when the image receptor object distance is short

16
Q

what can ghost images be formed in

A

earrings
tongue studs
anything situated between the x ray source and the centre of rotation

17
Q

what can we also produce ghost images of

A

the patients normal anatomy

18
Q

what is the disadvantages of panoramic

A

ghost images

19
Q

when do positioning errors occur

A

when the patient isn’t found in the focal trough

20
Q

what are common positioning errors

A

chin down
chin up
AP positioning error
rotational

21
Q

what are the issues with the chin being down

A

extenuated smily face as the posterior teeth are higher than we expected it to be

22
Q

what are the issues with the chin being up

A

inverted occlusal plane
grumpy face
upper incisors fall out of the focal trough-out of focus, blurred bigger

23
Q

what happens if the patients teeth are too far back from the image observer

A

big teeth

magnified out of focus

24
Q

advantages of panoramic radiography

A

shows the entire dentition
time efficient- takes 8-10 seconds
radiation dose may be lower than a full mouth surgery of intra oral images
well tolerated by patients
can be used eve n when patient can’t fully open mouth or pronounced gag reflex

25
Q

disadvantages of panoramic

A

only appreciate images within the focal trough
might have overlapping of teeth- difficult to see inter proximal caries
careful patient positioning
superimposition of soft tissues and air shadows causes misinterpretation
poor resolution one detail- caries detection and imaging of fine perio tissues
long exposure susceptible to damage by movement or difficult with children

26
Q

what anatomy do we see on OGP- four white lines

A
involves maxillary antrum
post wall of the maxillary sinus 
floor of the max sinus 
hard palate 
zygomatic butress
27
Q

key features of the zygomatic buttress

A

cortical curve of the buttress

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