CT Image Quality

Question 1

What can be done to reduce the appearance of noise (not the noise itself) on a CT image?

Answer 1

we can use a reconstruction filter, aka kernal, to reduce the appearance of noise - such as a soft tissue algorithm.

Question 2

What is the most common reason to use a lower matrix than the standard 512 x 512?

Answer 2

to speed up reconstruction time (less of a problem with modern faster scanners)

Question 3

Will using a smaller reconstructed FOV inherently mean that you will have more noise?

Answer 3

Yes! Less photons = more noise.

Question 4

What is another name for ‘scan circle violation’ artifact?

Answer 4

‘out-of-field’ artifact

Question 5

What causes ‘scan circle violation’ aka ‘out-of-field’ artifact?

Answer 5

very large patients where tissue is too close to the side of the gantry and perhaps the scan table being set too high or too low

Question 6

What is a good way to reduce beam hardening artifact?

Answer 6

use thinner slices and increase radiation dose

Question 7

Ring artifacts are characteristic of what generation of CT scanner?

Answer 7

3rd Generation

Question 8

Cerebral blood flow, Mean Transit Time, and Cerebral blood volume are all associated with what kind of study?

Answer 8

brain perfusion imaging