CT MOCK EXAM PAPER #2 QUSTIONS
WITH COMPLETE ANSWERS
The multiple-scan average dose (MSAD) is used to describe the:
a. dose received in a single CT section
b. amount of radiation absorbed in a quantity of air
c. average dose to a single section within a scan of multiple sections
d. cumulative dose for an entire helical scan - Answer-c. average dose to a single
section within a scan of multiple sections
The number of electrons that flow from the cathode to the anode in the tube is
controlled by the:
a. mA
b. anode target
c. collimation
d. kV - Answer-a. mA
Which of the following has the highest patient dose assuming all other parameters are
the same?
a. mA=150, rotation time=3 seconds
b. mA=400, rotation time=1 second
c. mA=200, rotation time=2 seconds
d. mA=200, rotation time=1 second - Answer-a. mA=150, rotation time=3 seconds
Which of the following may result from exposing embryo to x-ray radiation?
a. deformities
b. miscarriage
c. mental retardation
d. All of the above - Answer-d. All of the above
On a multi-row detector scanner, a radiation penumbra may be found:
a. on evry other slice
b. on every slice
c. only on the trailing edges of the slices
d. only on the first and last slices of the slice volume - Answer-d. only on the first and
last slices of the slice volume
Increasing _________ results in lowering the patient dose.
,a. pitch
b. table increment
c. mAs - Answer-a. pitch
b. table increment
A 25 year old female is scheduled for a CT scan of the sinuses. She is not absolutely
certain that she is not pregnant and it has been three weeks since her last menstrual
period. Which of the following is the best course of action?
a. perform the exam immediately, while she is experiencing sinus problems
b. postpone the procedure until she is more certain of her condition
c. cancel the procedure indefinitely
d. suggest she get an MRI instead - Answer-b. postpone the procedure until she is more
certain of her condition
Which of the following units is used to quantify effective dose?
a. roentgens (R)
b. grays (Gy)
c. sieverts (Sv)
d. curies (Ci) - Answer-c. sieverts (Sv)
Which of the following could be the dose experienced by the pituitary from a typical CT
brain scan?
a. 5 mGy
b. 9 rads
c. 2 rads
d. 1 mGy - Answer-c. 2 rads
Which of the following is a possible long-term effect of repeated exposure to radiation?
a. cataracts
b. cancer
c. decrease in life expectancy
d. all of the above - Answer-d. all of the above
Which of the following does NOT minimize the radiation dose to the patient?
a. decreasing the distance from the x-ray tube to the patient
b. filtration of the low energy photons from the x-ray beam
c. increasing the pitch
d. pre-patient collimation - Answer-a. decreasing the distance from the x-ray tube to the
patient
,On a single-row detector scanner, which of the following does NOT decrease the patient
dose?
a. decreasing the scan time while leaving the MA constant
b. reformat the datta instead of re-scanning
c. increasing the pitch
d. decreasing the slice thickness while covering the same anatomical - Answer-d.
decreasing the slice thickness while covering the same anatomical
If there is no overlap or gap between adjacent slices of a CT scan, CTDI __________
MSAD.
a. equals
b. is less than
c. is slightly greater than
d. is much greater than - Answer-a. equals
Which of the following is TRUE regarding a radiation penumbra?
a. it occurs because the collimator is broken
b. it is accounted for in the calculation of the MSAD
c. it is radiation that extends outside of the imaging region - Answer-b. it is accounted
for in the calculation of the MSAD
c. it is radiation that extends outside of the imaging region
To modify a standard CT protocol so that it is appropriate for children, which of the
following should be decreased?
a. pitch
b. kVp
c. mAs - Answer-b. kVp
c. mAs
Which of the following reduces patient dose at the expense of increasing the apparent
noise in the image?
a. pitch
b. mAs
c. table increment
d. kVp - Answer-b. mAs
Which of the following is the correct action to take if a patient arrives with obvious head
trauma, expecting a CT of the brain, but the paperwork requests a pelvic CT?
a. request clarification from the ordering physician
b. perform only a scan of the brain
, c. perform both exams
d. perform only a scan of the pelvis - Answer-a. request clarification from the ordering
physician
During a CT scan, the patient must be monitored:
a. by a pulse oximeter
b. occasionally
c. visually and verbally
d. by a nurse - Answer-c. visually and verbally
The average CT value for blood is approximately:
a. -50 HU
b. 0 HU
c. +45 HU
d. +100 HU - Answer-c. +45 HU
Which of the following manipulations involves the use of image data?
a. adjusting the width and level of a window setting
b. decreasing the DFOV
c. changing the algorithm selection
d. increasing the matrix size - Answer-a. adjusting the width and level of a window
setting
Which of the following window level and width settings were used to display this image?
a. level= -700, width= 2000
b. level= +50, width= 400
c. level= +150, width= 1000
d. level= +250, width= 4000 - Answer-d. level= +250, width= 4000
Which of the following types of image noise can be most easily reduced by the CT
technologist?
a. electronic noise
b. artifactual noise
c. quantum noise
d. detector noise - Answer-c. quantum noise
When one is choosing a window to display a CT image, the width defines the:
a. midpoint of the range of pixels displayed
b. range of CT numbers (pixels) to be displayed
c. range of pixel values included in an ROI
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