Other Imaging Modalities 2

Question 1

What is CBCT?

Answer 1

Low dose, multi planar imaging

Images made up of isotopic voxels
- cubes of data with equal measurements
- look at images in three planes: axial, coronal and sagittal

Question 2

CBCT vs CT scan?

Answer 2

CBCT is cone vs CT is a fan shaped beam

CBCT lower dose than CT

CBCT good for bone imaging but CT good for soft tissue

Patient upright for CBCT and horizontal for CT

Question 3

What are the effective doses for intra oral periapical / bitewing

Answer 3

0.3 - 21.6 uSv

Question 4

What is the effective dose of a panoramic radiograph?

Answer 4

2.7 - 38 uSv

Question 5

What is the effective dose for a CBCT of 5-10cm height and over 15cm height

Answer 5

5-10cm = 18-674 uSv

Over 15 = 30 - 1025 uSv

Question 6

What is the effective dose of CT Scan of maxilla and mandible?

Answer 6

430 - 860 uSv

Question 7

What imaging is needed for TMDs

Answer 7

Myofascial pain - none

Arthralgia / Degenerative disease - CBCT

Internal derangement - MRI gold standard

Question 8

How can MRI be used for internal derangement?

Answer 8

Disc visualised on MRI

Can determine if joint has derangement with or without reduction and which way the disc removes in relation to condyle

Question 9

Difference between CT and MRI?

Answer 9

MRI has no radiation dose

MRI takes longer

More contraindications for MRI
- pacemakers
- cochlear implants
- claustrophobia

MRI better for assessing
- perineural spread
- bone invasion and bone marrow changes
- soft tissue characteristics