Deck 41: Computed Tomography

Question 1

Computed tomography sections are available as

A)coronal.
B)transverse.
C)sagittal.
D)all of the above

Answer 1

all of the above

Question 2

The CT radiation beam is collimated

A)at the tube exit.
B)at the detector entrance.
C)pre-patient and post-patient.
D)all of the above

Answer 2

all of the above

Question 3

The localization image produced by the CT scanner is technically called a/an

A)volume rendered image.
B)scout film.
C)scanogram.
D)FOV image.

Answer 3

scanogram.

Question 4

A series of tissue density values that evolved for CT measurements is called ____ units.

A)Hounsfield
B)H & D
C)attenuation
D)iterative

Question 5

The ____ is how well the detectors receive photons from the patient.

A)capture efficiency
B)absorption efficiency
C)conversion efficiency
D)response time

Question 6

To achieve coronal or sagittal sections,

A)the gantry is repositioned.
B)the patient is repositioned.
C)reconfiguration software is implemented.
D)none of the above

Question 7

The CT console provides the radiographer access to

A)the software program.
B)data acquisition.
C)data display.
D)all of the above

Question 8

Modern pulsed CT scanners operate at

A)120 kVp.
B)1 to 5 msec. pulses.
C)up to 1,000 mA.
D)all of the above

Question 9

The most recent generation of CT scanners use a ____ motion.

A)translate-rotate
B)helical
C)linear
D)elliptical

Question 10

Contemporary CT scanners use solid state detectors.These detectors utilize

A)sodium iodide crystals.
B)rare earth ceramic scintillators.
C)xenon gas.
D)freon gas.

Question 11

The resolution of the CT image depends on the

A)pixel.
B)voxel.
C)matrix size.
D)all of the above

Question 12

The CT table is

A)made of carbon graphite.
B)rated for maximum weight.
C)motor-driven.
D)all of the above

Question 13

The process of combining detector elements into various combinations in order set slice thickness is called detector

A)modulation.
B)dose efficiency.
C)binning.
D)interpolation.

Question 14

First-generation CT scanners scanned the ____ only.

A)head
B)thorax
C)abdomen
D)pelvis

Question 15

The smaller the scan field size, the

A)better the resolution.
B)faster the scan time.
C)less the risk of motion.
D)all of the above

Question 16

The CT radiographer usually varies the ____ to control the primary beam.

A)mA
B)time
C)kVp
D)distance

Question 17

The gantry of the CT unit contains the

A)post-processing workstation.
B)operator's interface.
C)x-ray tube.
D)all of the above

Question 18

The ____ is determined by how well the detector converts the absorbed photon information to a digital signal for the computer.

A)capture efficiency
B)absorption efficiency
C)conversion efficiency
D)response time

Question 19

The ____ is how well the detectors convert incoming photons.

A)capture efficiency
B)absorption efficiency
C)conversion efficiency
D)response time

Question 20

A ____ artifact is caused by motion.

A)beam-hardening
B)ring
C)star
D)streak

Question 21

If the table is moving at 10 mm/sec., and a section thickness of 8 mm is being acquired, what is the pitch?

Question 22

The CTDI dose measurement

A)is slice-based.
B)takes into account the total amount of irradiated tissue.
C)represents the average total dose to the patient during the examination.
D)measures entrance skin exposure (ESE).

Question 23

If the table is moving at 5 mm/sec., and a pitch of 0.8 is being used, what is the section thickness?

Question 24

CT image data is acquired in the

A)coronal plane and reconstructed in the axial plane .
B)transverse plane and reconstructed in any plane.
C)sagittal plane .
D)axial plane and reconstructed in the coronal plane.

Question 25

The range of CT numbers or Hounsfield Units varies from

A)100 to 300.
B)-100 to +300.
C)-1000 to +3000.
D)1000 to +3000.

Question 26

If the table is moving at 12 mm/sec., and a section thickness of 10 mm is being acquired, what is the pitch?

Question 27

As noise increases in a CT image,

A)low contrast resolution increases.
B)dose to the patient increases.
C)low contrast resolution decreases.
D)both a and c

Question 28

The process of modifying pixel values by a mathematical formula is called

A)convolution.
B)deconvolution.
C)calculus.
D)interpolation.

Question 29

In order for a CT x-ray photon to be measured, it must
1)enter the detector
2)be absorbed by the detector material
3)transmit through the detector to be back-projected
4)have sufficient energy to undergo a Compton interaction
5)be converted to light and then electrical energy as a signal

A)1, 3, 4, and 5
B)1, 2, and 5
C)1, 2, and 4
D)1, 4, and 5

Question 30

A ____ artifact is caused by detector error.

A)beam-hardening
B)ring
C)star
D)streak

Question 31

The primary mathematical method used in the creation of computerized medical images is the ____ transformation.

A)interpolation
B)Hounsfield
C)algorithm
D)Fourier

Question 32

The calculation of CT numbers is based upon the calculation of

A)half-value layers.
B)half-lives.
C)attenuation coefficients.
D)pitch.

Question 33

MSCT scanners have evolved greatly over the last few years, particularly with regard to slice combinations, scanning speed, and clinical utility.As these scanners gather more slices of data per rotation, a major technological challenge is

A) the amount of data handled by the computer.
B) the number of images to be analyzed by the clinician.
C) developing technologies to minimize dose.
D) all of the above

Question 34

CT scan pitch uses all of the following technical parameters EXCEPT

A)slice thickness.
B)360-degree gantry rotation.
C)acquisition mAs .
D)table increment.

Question 35

A ____ artifact is caused by attenuation of the beam as it passes through the patient.

A)beam-hardening
B)ring
C)star
D)streak

Question 36

With MSCT scanners, resolution is primarily determined by

A) prepatient collimation.
B) dose.
C) collimation at the detector.
D) gantry rotation speed.

Question 37

If the table is moving at 5 mm/sec., and a pitch of 1.5 is being used, what is the section thickness?

Question 38

If a pitch of 1.0 is being used with a section thickness of 8 mm, what is the proper table speed?

Question 39

If a pitch of 0.5 is being used with a section thickness of 10 mm, what is the proper table speed?

Question 40

A ____ artifact is caused by the presence of metal in the patient.

A)beam-hardening
B)ring
C)star
D)streak