Deck 28: Computed Tomography

Question 1

Many CT x-ray tubes have the capacity for millions of _____ with each exam.

A) heat units
B) rotations
C) volts
D) Hertz

Answer 1

heat units

Question 2

The second-generation CT scanners had the disadvantage of increased _____.

A) beam scatter
B) scanning time
C) ring artifacts
D) number of translations

Answer 2

beam scatter

Question 3

The principal drawback of the first-generation CT scanner was the _____.

A) high patient dose
B) long scanning time
C) translate-rotate assembly
D) degree of rotation

Answer 3

long scanning time

Question 4

The concentration of scintillation detectors affects the _____ of the CT image.

A) spatial resolution
B) contrast resolution
C) overall density
D) motion artifact

Question 5

Filtered back projection in CT refers to _____.

A) spatial resolution
B) pre-patient collimation
C) beam filtration
D) image reconstruction

Question 6

CT scanners operate on _____ voltage generation.

A) single-phase
B) three phase
C) high frequency
D) twelve-pulse

Question 7

Each pixel of information in the CT image contains numerical information in _____ units.

A) voxel
B) reconstruction
C) Hounsfield
D) pixel

Question 8

The new development in the fourth generation CT scanner is the _____.

A) stationary detector array
B) fan beam
C) reduced patient dose
D) ring artifact

Question 9

The first generation of computed tomography used _____ detector(s).

A) one
B) two
C) three
D) four

Question 10

The reduction in _____ was the principal advantage of the second-generation CT scanners.

A) image noise
B) patient dose
C) scanning time
D) scatter radiation

Question 11

What is the principal disadvantage of third generation CT scanners?

A) slow speed
B) ring artifacts
C) patient dose
D) poor reconstruction

Question 12

The pixel size is reduced when the _____ size is increased and the _____ size is fixed.

A) field of view, matrix
B) matrix, field of view
C) Hounsfield unit, field of view
D) field of view, Hounsfield unit

Question 13

Each sweep of the source-detector around the body during CT is called a _____.

A) rotation
B) reconstruction
C) translation
D) projection

Question 14

Each CT projection is _____.

A) displayed on the monitor
B) stored on the computer
C) printed on film
D) all of the above

Question 15

The cross-sectional anatomy is translated into _____ during CT reconstruction.

A) an intensity profile
B) attenuation patterns
C) a matrix of values
D) effective atomic numbers

Question 16

Each CT projection records variations in _____.

A) density and contrast
B) motion and noise
C) spatial resolution and contrast resolution
D) mass density and effective atomic number

Question 17

The patient dose in CT is determined by the _____ collimator.

A) predetector
B) prepatient
C) postpatient
D) both A and B

Question 18

The time from the end of CT imaging to image appearance is called the _____ time.

A) reconstruction
B) translation
C) projection
D) Hounsfield

Question 19

The third generation of CT scanners allowed for further reduction in _____.

A) scanning time
B) scattered radiation.
C) fan-beam width
D) both A and B

Question 20

The _____ generation of CT scanners was the first to have the fan beam transect the entire patient at all times.

A) first
B) second
C) third
D) fourth

Question 21

The degree of spatial resolution in any CT imaging system is limited to the size of the _____.

A) voxel
B) FOV
C) matrix
D) pixel

Question 22

The CT scanner must be calibrated so that _____ is at CT number zero.

A) water
B) Plexiglas
C) nylon
D) polyethylene

Question 23

Image noise in CT scanning depends on _____.

A) pixel size
B) detector efficiency
C) slice thickness
D) all of the above

Question 24

CT imaging has excellent _____ because of the narrow beam collimation.

A) spatial frequency
B) noise reduction
C) contrast resolution
D) spatial resolution

Question 25

A high variation in pixel values in a homogenous phantom is a measure of _____.

A) spatial resolution
B) image noise
C) contrast resolution
D) motion artifact