CT

Question 1

CT stands for

Answer 1

computerized tomography

Question 2

Tomos

Answer 2

to cut or section in Greek

Question 3

Tomography

Answer 3

a special technique to show in detail, images of structures lying in a predetermined plane of tissue while blurring or eliminating detail in images or structures in other planes

Question 4

Focal plane or region of interest

Answer 4

section or layer at which minimal blurring occurs

Question 5

ROI is

Answer 5

a fixed point in the anatomy of the patient

Question 6

Fulcrum

Answer 6

central point/ pivot point. Can be moved up and down to change the level at which the anatomy is blurred

Question 7

Blur

Answer 7

distortion or blurring of the anatomy above and below the ROI

Question 8

CT was invented in 1971 by

Answer 8

Sir Godfrey Hounsfield

Question 9

CT also known as

Answer 9

CAT (computerized axial tomography)

Question 10

CT used an x-ray machine that acquires images that look like

Answer 10

slices of a loaf of bread

Question 11

An xray tube emitting a fan shaped beam of X-rays rotates _ degrees around a gantry (opening of the center of the machine) and the patient within it

Answer 11

360

Question 12

Voxel

Answer 12

volume measurement in 3D imaging

Question 13

Each voxel in a CT image is also calculated into a density measurement called a

Answer 13

Hounsfield unit (HU) or CT number

Question 14

The scale is based on attenuation with pure water assigned a CT number of

Answer 14

0

Question 15

HUs also affect

Answer 15

how images are displayed in terms of brightness and contrast

Question 16

HUs can also be measured with a cursor to help the DVM determine

Answer 16

the nature of a lesion

Question 17

50 HU lesion may be

Answer 17

fat

Question 18

160 HU lesion is

Answer 18

calcium

Question 19

Two types of field of view (the area seen in the image)

Answer 19

scan field of view (SFOV): number of detectors covered by x-ray beam
display field of view (DFOV): will either be equal to or smaller than the SFOV

Question 20

_ and _ typically tend to be higher than standard radiography

Answer 20

kV and MAs

Question 21

Methods of scanning

Answer 21

spiral or conventional

Question 22

ALARA

Answer 22

As least as reasonably achievable

Question 23

Original scanners acquired images in slices _ mm thick but these missed small lesions

Answer 23

10

Question 24

Multislice scanners are able to acquire images slices thinner than

Answer 24

1mm

Question 25

Scout view (scanogram)

Answer 25

looks like a radiograph and allows the operator to choose the regions included in a scan

Question 26

conventional scanning

Answer 26

refers to the table motion as done by the original CT scanners

Question 27

spiral or helical scanning

Answer 27

X-ray tube and detectors rotate continuously which saves a delay between scans

Question 28

pitch

Answer 28

the ratio between table movement (in mm) and CT slice thickness

Question 29

CT scanners allow technologists to

Answer 29

make any changes to a setup as needed

Question 30

some protocols may require

Answer 30

IV contrast, angiography, abdominal scans with contrast, injecting contrast into the spinal canal via lumbar puncture (myelogram)

Question 31

Modern multi slice scanners have up to _ detectors in the width of their array

Answer 31

256

Question 32

CT remains an excellent diagnostic for

Answer 32

assessing trauma, broken bones, abdominal injuries, images of brain and sinus if MRI not available

Question 32

CT used to be primary modality for imaging the head and spine, but _ is now the gold standard

Answer 32

MRI