Panoramic radiography

Question 1

What principles does panoramic radiography use?

Answer 1

Tomography

Question 2

Describe the movement of the film in relation to the tube

Answer 2

Film and tube move in opposite directions

Question 3

What is the significance of the focal trough

Answer 3

Objects within the focal trough are sharp on image.

Objects out with appear blurred

Question 4

What are the components of the panoramic

Answer 4

Film within cassette
Film sensitive to light
Intensifying screens

Question 5

What is the function of the intensifying screen?

Answer 5

Absorbs X-rays and emits light

Reduces the dose but also image clarity

Question 6

What are the disadvantages of the intensifying screen?

Answer 6

Emits light in all directions

Image quality poorer than direct action film

Question 7

What replaces the intensifying screen in digital panoramics?m

Answer 7

Solid state censor

Question 8

What are the advantages of panoramic radiography?

Answer 8

Images teeth and bone with minimal discomfort

Reduced dose in comparison to full mouth PAs

Question 9

What are the indications for panoramic radiography?

Answer 9

Assessment of unerupted teeth 
Evaluation of cysts and tumours
Allows comparison of both sides 
Show heigh of mandible and ID canal
Shows sinus walls

Question 10

What are the main problems re. Panoramics?

Answer 10

Lack of fine detail
Superimposition eg. Cervical spine re. Anterior teeth
Exposure time can be up to 14 seconds
Magnification

Question 11

What planes do the light beams mark?

Answer 11

Mid Sagital plane vertically

Frankfurt plane horizontally

Question 12

What is the dose of DPT?

Answer 12

3.85- 30 micro sv

Question 13

What is the average background radiation in the UK?

Answer 13

2.5 milli sv

Question 14

What hard tissues structures can be seen on DPT

Answer 14

Teeth
Mandible
Maxilla
Hard palate
Zygomatic arches and zygoma
Styloid process
Hyoid bone
Septum and conchae
Orbital rim

Question 15

What soft tissue structures can be seen on panoramic rad?

Answer 15

Ear lobe
Nasal cartilage
Soft palate
Tongue
Lips

Question 16

Where are the main air shadows?

Answer 16

Between lips
Oral cavity
Oropharynx
Nasopharynx

Question 17

What are ghost images?

Answer 17

Images of a structure on one side projected onto the other side

Question 18

What are commonly seen as ghost images?

Answer 18

Ramus and angle
Hard palate
Foreign bodies

Question 19

What happens to image quality if patient is positioned too far back?

Answer 19

Magnification of anterior teeth horizontally

Question 20

What happens to image quality if patient is positioned too far forwards?

Answer 20

Magnification vertically

Question 21

What happen to image in pt is position chin down

Answer 21

Image appears overly curved

Question 22

What happens to image if pt is positioned chin up?

Answer 22

Flat occlusal plane

Question 23

What happens to image if pt is slumped?

Answer 23

Spine can obscure image

Question 24

Why are panoramic images not gold standard for caries diagnosis?

Answer 24

Poor fine detail
Over lap
Superimposition of air

Question 25

For what sort of caries may dpts be better for diagnosis.

Answer 25

Occlusal caries

Question 26

With regards to perio disease, what are the disadvantages of dpt re. Diagnosis

Answer 26

Poor in anterior region due to spine superimposition

Overlap may obscure bone