CT Scans

Question 1

What does CT stand for?

Answer 1

Computed Tomography

Question 2

Are CT scans 2D or 3D?

Answer 2

3D

Question 3

Who made the first X-ray, when, and what of?

Answer 3

Röntgen
1895
Of his Wife’s hand.

Question 4

What is the name of the hole is the CT scanner and how large is it?

Answer 4

Boar

Aperture of 60cm

Question 5

What is the name of what the patient lies on in a CT scanner?

Answer 5

Couch

Question 6

What type of shape beam does a CT scanner have?

Answer 6

Fan beam

Question 7

Does the couch move the patient through the boar of the scanner move around the patient?

Answer 7

Patient positioning table moves through the scanning field (at a constant speed)

Question 8

kVp of an X-ray tube

Answer 8

120

Question 9

How long is one revolution of an X-ray tube?

Answer 9

<250ms

Question 10

What does a CT scanner measure to create an image?

Answer 10

The X-ray attenuation through the object/tissue

Question 11

Define voxel

Answer 11

Volume element

Question 12

Values of Water, Air and Bone in Hounsfield Units

Answer 12

Water = 0, Air = -1000, Bone > +400

Question 13

What colour is bone and air on a CT

Answer 13

Bone is white

Air is black

Question 14

Name 4 applications of CTs

Answer 14

Coronary CT
Angiograph
Orthopedics
Oncology

Question 15

What is a contrast enhanced CT scan?

Answer 15

Iodine-based contrast injected into the patient

This will show up on a CT scan (to create iodine based contrast)

Question 16

Negatives of CT scans

Answer 16

Imaging dose, small risk of cancer
Not ideal for moving parts (i.e. need a 4D scanner)
Not great with soft tissue definition

Question 17

Uses of CT scans in cardiac/coronary?

Answer 17

Identify calcification

and occlusion of coronary arteries

Question 18

What is stenoisis

Answer 18

the narrowing or restriction of a blood vessel or valve that reduces blood flow.

Question 19

What stages of oncology are CT scans used in?

Answer 19

Diagnostic - identify tumour
Planning - delineation of tumour for radiotherapy
Treatment response - see if treatment has been successful, has tumour shrunk? Returned?

Question 20

What is Filtered Back Projection?

Answer 20

Filtered back projection is an analytic reconstruction algorithm (removes blurring obtained from normal back projection). Backprojection reconstructs an image by taking each view and smearing it along the path it was originally acquired.