CT exam

Question 1

Purpose of bow tie filter

Answer 1

Counteract beam hardening

Question 2

Typical CT kVp

Answer 2

125

80-140

Question 3

Typical CT ma

Answer 3

100-400

Question 4

Which collimators help determine slice thickness ?

Answer 4

Post patient collimators

Question 5

Will a thicker slice increase or decrease SNR?

Answer 5

Increase

Question 6

What determines slice thickness in a multi slice CT

Answer 6

Beam thickness

Question 7

Why can’t top hat be achieved ?

Answer 7

FSS
Patient movement
Collimating / penumbra

Question 8

What determines longitudinal spatial in spiral CT?

Answer 8

Slice thickness
Table move per rotation
Reconstruction algorithm

Question 9

What can Dey instability cause ?

Answer 9

Ring artifcart

Question 10

What do solid-state scintilators imprive ?

Answer 10

QDE

Question 11

What will cross talk reduce ?

Answer 11

Spatial and contrast

Question 12

What is another name for anisotropic multi slice det

Answer 12

Adaptive

Question 13

What do multi - slice dets also determine?

Answer 13

Slice thickness

Question 14

What’s DAS??

Answer 14

Converting a measured radiation to a computer signal

Question 15

What are the 4 data types ?

Answer 15

Measurement
Raw
Convolved
Image reconstruction

Question 16

Which data type corrects scatter, faulty dets and beam hardening ?

Answer 16

Measurement data

Question 17

Which data type resolves Star artifacr through filtered back projection?

Answer 17

Convolved

Question 18

Which is the iterative algorithm ??

Answer 18

The box number thingies

Question 19

Name 4 basic reconstruction principles

Answer 19

Fourier
Convultation
Interpolation
Iterative

Question 20

What’s a Wide window range ?

Answer 20

400-2000

Question 21

What’s a narrow window range?

Answer 21

50-350

Question 22

What will a large FOV cause ?

Answer 22

SNR

Question 23

What is photon flux ?

Answer 23

Number of photons

Question 24

What will narrow collimation cause ?

Answer 24

Reduce scatter and improve contrast but thicker slices inprove SNR

Question 25

What will a faster gantry rotation cause ?

Answer 25

Decrease in contrast

Question 26

What will an increase pixel width cause

Answer 26

SNR reduce

Question 27

What 2 artifacrs are associated with beam hardening ?

Answer 27

Cupping

Streaking

Question 28

What can be done to overcome partial volume averaging ?

Answer 28

Thinner slices

Question 29

What are ting artifacrs associated with?

Answer 29

3rd gens.

Bad dets

Question 30

How are ring artefacts eliminates ??

Answer 30

Raw data

Question 31

What do helical artificers increase with ??

Answer 31

Pitch