MODULE 4 CT image appearance || 100% Actual Answers.
1. "The ability to differentiate slight differences in density on an image" is the definition of:
a. Contrast
b. Dose
c. Resolution
d. Noise correct answers a. Contrast
2. Which of the following would improve spatial resolution?
a. Decrease the kVp
b. Decrease the reconstruction field of view
c. Increase the mAs
d. Increase slice thickness correct answers b. Decrease the reconstrucation field of view
3. Noise is more apparent in an image when:
a. Using a high mAs
b. A smooth reconstruction filter is used
c. There is an insufficient number of photons to make the image
d. The slice thickness is greater correct answers c. There is an insufficient number of photons to
make the image
4. Which of the following affects the patient dose?
1. Rotation time
2. Anatomical coverage
3. Pitch
a. 1,2&3
b. 1&3
c. 2&3
d. 1&2 correct answers a. 1,2&3
5. Which of the following statements is TRUE?
1. CT scanners usually have saved protocols for various types of clinical studies
2. Varying a single CT scan parameter can simultaneously affect the ability to visualize small
structures on the image and how grainy the image appears
3. A new value for every CT imaging parameter must be entered prior to each scan
a. 1 only
b. 2 only
c. 1&2
d. 2&3 correct answers c. 1&2
6. If all other factors are held constant, a scan using ___ mAs will produce an image with the
least amount of apparent noise.
a. 200
b. 300
c. 250
d. 100 correct answers b. 300
, 7. Which of the following will yield the lowest patient dose (assuming all other parameters are
the same)?
a. mA=200, 1 sec rotation
b. mA=100, 0.5 sec rotation
c. mA=200, 0.5 sec rotation
d. mA=100, 1 sec rotation correct answers b. mA=100, 0.5 sec rotation
8. Which of the following could be used to compensate for the increased image noise which
results when a reduced reconstruction FOV is used?
1. Increased mAs
2. Increased slice thickness
3. Decreased matrix
a. 2&3
b. 1,2&3
c. 1&2
d. 1&3 correct answers b. 1,2&3
9. If a thin slice is used, which of the following would help reduce the image noise?
a. Increased mAs
b. Decreased kV
c. Increased matrix
d. Reduced reconstruction field of view correct answers a. Increase mAs
10. Which of the following CT scan parameters affect me the contrast of the image?
a. kVp
b. Reconstruction field of view
c. mAs
d. Slice thickness correct answers a. kVp
11. To convert an abdominal protocol for adults to an abdominal protocol for pediatric patients,
the kVp should be ___ to achieve optimal tissue contrast.
a. Left alone
b. Tripled
c. Doubled
d. Decreased correct answers d. Decreased
12. On MDCT, the final, reconstructed slice thickness is determined by the:
a. Pitch
b. Reconstruction interval
c. Collimation of the X-ray beam
d. Number of rows of detectors and the size of the detectors whose attenuation data gets
combined correct answers d. Number of rows and detectors and the size of the detectors whose
attenuation data gets combined
13. Which of the following can be changed retrospectively?
1. "The ability to differentiate slight differences in density on an image" is the definition of:
a. Contrast
b. Dose
c. Resolution
d. Noise correct answers a. Contrast
2. Which of the following would improve spatial resolution?
a. Decrease the kVp
b. Decrease the reconstruction field of view
c. Increase the mAs
d. Increase slice thickness correct answers b. Decrease the reconstrucation field of view
3. Noise is more apparent in an image when:
a. Using a high mAs
b. A smooth reconstruction filter is used
c. There is an insufficient number of photons to make the image
d. The slice thickness is greater correct answers c. There is an insufficient number of photons to
make the image
4. Which of the following affects the patient dose?
1. Rotation time
2. Anatomical coverage
3. Pitch
a. 1,2&3
b. 1&3
c. 2&3
d. 1&2 correct answers a. 1,2&3
5. Which of the following statements is TRUE?
1. CT scanners usually have saved protocols for various types of clinical studies
2. Varying a single CT scan parameter can simultaneously affect the ability to visualize small
structures on the image and how grainy the image appears
3. A new value for every CT imaging parameter must be entered prior to each scan
a. 1 only
b. 2 only
c. 1&2
d. 2&3 correct answers c. 1&2
6. If all other factors are held constant, a scan using ___ mAs will produce an image with the
least amount of apparent noise.
a. 200
b. 300
c. 250
d. 100 correct answers b. 300
, 7. Which of the following will yield the lowest patient dose (assuming all other parameters are
the same)?
a. mA=200, 1 sec rotation
b. mA=100, 0.5 sec rotation
c. mA=200, 0.5 sec rotation
d. mA=100, 1 sec rotation correct answers b. mA=100, 0.5 sec rotation
8. Which of the following could be used to compensate for the increased image noise which
results when a reduced reconstruction FOV is used?
1. Increased mAs
2. Increased slice thickness
3. Decreased matrix
a. 2&3
b. 1,2&3
c. 1&2
d. 1&3 correct answers b. 1,2&3
9. If a thin slice is used, which of the following would help reduce the image noise?
a. Increased mAs
b. Decreased kV
c. Increased matrix
d. Reduced reconstruction field of view correct answers a. Increase mAs
10. Which of the following CT scan parameters affect me the contrast of the image?
a. kVp
b. Reconstruction field of view
c. mAs
d. Slice thickness correct answers a. kVp
11. To convert an abdominal protocol for adults to an abdominal protocol for pediatric patients,
the kVp should be ___ to achieve optimal tissue contrast.
a. Left alone
b. Tripled
c. Doubled
d. Decreased correct answers d. Decreased
12. On MDCT, the final, reconstructed slice thickness is determined by the:
a. Pitch
b. Reconstruction interval
c. Collimation of the X-ray beam
d. Number of rows of detectors and the size of the detectors whose attenuation data gets
combined correct answers d. Number of rows and detectors and the size of the detectors whose
attenuation data gets combined
13. Which of the following can be changed retrospectively?
