panoramic radiography

Question 1

what is panoramic radiography

Answer 1

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

Question 2

what is the greyscale is dependant on

Answer 2

the degree of absorption

Question 3

what is tomography

Answer 3

coordinated source of movement of the image receptor and the tube

Question 4

what does tomography generate

Answer 4

an in focus slice of anatomy

Question 5

what does the technique produce

Answer 5

a curved in focus slice called the focal trough

Question 6

what do we want the dental trough to coincide with

Answer 6

the entire dentition

Question 7

what is the x ray source and the tube called

Answer 7

the gantry

Question 8

what happens to the image outside the focal trough

Answer 8

they are blurry

Question 9

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

Answer 9

8 degree angulation

Question 10

how are ghost images produced

Answer 10

anything between the x ray source and the centre of rotation

Question 11

characteristics of ghost imaged compared to the real image

Answer 11

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

Question 12

why is the ghost image larger

Answer 12

due to beam convergence

Question 13

why is the ghost image higher

Answer 13

due to the beam angulation

Question 14

how dow we get a crisp beam

Answer 14

with less divergence of the x ray beam

Question 15

when is the image in focus

Answer 15

when the image receptor object distance is short

Question 16

what can ghost images be formed in

Answer 16

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

Question 17

what can we also produce ghost images of

Answer 17

the patients normal anatomy

Question 18

what is the disadvantages of panoramic

Answer 18

ghost images

Question 19

when do positioning errors occur

Answer 19

when the patient isn’t found in the focal trough

Question 20

what are common positioning errors

Answer 20

chin down
chin up
AP positioning error
rotational

Question 21

what are the issues with the chin being down

Answer 21

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

Question 22

what are the issues with the chin being up

Answer 22

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

Question 23

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

Answer 23

big teeth

magnified out of focus

Question 24

advantages of panoramic radiography

Answer 24

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

Question 25

disadvantages of panoramic

Answer 25

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

Question 26

what anatomy do we see on OGP- four white lines

Answer 26

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

Question 27

key features of the zygomatic buttress

Answer 27

cortical curve of the buttress