Deck 28: Computed Tomography

Question 1

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

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

Answer 1

spatial resolution

Question 2

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 2

long scanning time

Question 3

What is the principal disadvantage of third-generation CT scanners?

A) Slow speed
B) Ring artifacts
C) Patient dose
D) Poor reconstruction

Answer 3

Ring artifacts

Question 4

CT scanners operate on ________________ voltage generation.

A) single-phase
B) three-phase
C) high-frequency
D) 12-pulse

Question 5

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 6

The new development in the fourth-generation CT scanner is the ________________.

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

Question 7

Filtered back projection in CT refers to ___________________.

A) spatial resolution
B) prepatient collimation
C) beam filtration
D) image reconstruction

Question 8

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 9

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 10

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

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

Question 11

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 12

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

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

Question 13

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

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

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

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

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

Question 16

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

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

Question 17

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 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 second-generation CT scanners had the disadvantage of increased ____________.

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

Question 20

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 21

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

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

Question 22

A high variation in pixel values in a homogeneous phantom is a measure of ________.

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

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

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

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

Question 25

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