Radiography (panoramics)

Question 1

How often do you need to update your radiograph license?

Answer 1

Every 5 years.

Question 2

What are SIX indications for DPRs?

Answer 2

• Bony lesion or unerupted tooth with size or position unable to be captured by intraoral radiographs
• Grossly neglected mouths
• Assessment of perio bone support for perio/implant/pros (with PA radiographs)
• Assessment of 8’s prior to surgical intervention
• Orthodontic assessment of unerupted/missing teeth
• Patient education

Question 3

What are one of the things a DPR machine will not let you adjust?

Answer 3

Exposure time (normallly takes 15 secs for motion to finish)

Question 4

In a DPR machine, where is the centre of rotation between?

Answer 4

Between the cassette carrier and the x-ray tube head.

Question 5

What is the gantry?

Answer 5

The arm that holds the x-ray tube head

Question 6

What direction does the collimation slit have (horizontal or vertical) and what angle is it at?

Answer 6

• Vertical slit collimation

- Slight upward tilt of beam

Question 7

Slight upward tilt does what to the resulting image?

Answer 7

• Slight magnification

- Vertical shape distortion

Question 8

If patient has their head rotated to the right, what happens to the image?

Answer 8

narrowing/sharpening of the right and widening of the left

Question 9

If patient has their head too close to the tubehead, what happens to the image?

Answer 9

• Structures lying buccally to focal trough (further from the tubehead) are reduced in size in horizontal plane (ie. minified or become narrower)
• Also are less sharp
• Superimposed on structures in the focal trough

Question 10

The centre of rotation is generally closer or further to the anteriors vs. posteriors? And what does this mean for the size of the focal trough?

Answer 10

• Closer to anteriors = narrower focal trough
• Further from posteriors = wider focal trough

NOTE: smaller focal trough for anteriors means that any very proclined or retroclined teeth will be hard to capture (e.g. crowns lined up but roots angled out of focal trough)

Question 11

For an object to form a secondary image, where does it need to be between?

Answer 11

Axis of rotation and the tube head.

Question 12

What are FOUR characteristics of secondary/ghost/artefact images?

Answer 12

• Blurred
• Larger
• Slightly higher
• Contralateral

NOTE: secondary image will have same orientation as primary image

Question 13

What are some things to check before you take a DPR?

Answer 13

• Confirm 3Cs
• Check pregnancy
• Jewellery removed
• Partial dentures removed (Full dentures stay)
• Hearing aids removed
• Select programme/exposure before positioning pt

Question 14

What are FOUR things to tell the pt before taking a DPR?

Answer 14

• Inform them that unit will move around them and to remain still
• Close eyes
• Swallow then keep tongue to roof of mouth
• Keep lips sealed and Breathe through nose

Question 15

What are some common errors when taking DPRs?

Answer 15

• Foreign object
• Palatoglossal airspace
• Lips open
• Head tilted
• Head rotated
• Slumped cervical spine
• Patient movement
• Shoulder interference

Question 16

What is parallax and how do we use it in everyday function?

Answer 16

Parallax is the difference in apparent position from two different lines of sight
- Closer objects have larger parallax vs. objects further away, so parallax can be used to judge distance.

Question 17

Non-OPG question:

What is the technique that involves taking two radiographs at 90degrees to each other?

Answer 17

Miller’s technique