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20 Cards in this Set
- Front
- Back
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The smallest object that can be resolved if reconstruction FOV of 24cm and a 512 X 512 matrix are used is ____________mm.
a. 0.47 b. 1.00 c. 2.13 d. 3.57 |
a. 0.47
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If the radiologist requires 2 mm thick contiguous slices through the pituitary, and 2.4 cm of coverage, ____________ slices are necessary?
a. 8 b. 20 c. 12 d. 13 |
c. 12
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Which of the following is NOT a result of reducing the reconstruction FOV?
1. improved spatial resolution 2. increased appearance of image noise 3. anatomical structures appear smaller a. 1 only b. 2 only c. 3 only d. 1,2 & 3 |
c. 3 only
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Which of the following parameters affects the contrast of a CT image?
a. reconstruction interval b. mAs c. kVp d. CT number |
c. kVp
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Which of the following parameters is responsible for partial volume averaging?
a. matrix size b. kVp c. slice thickness d. patient dose |
c. slice thickness
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On MDCT, the final reconstructed slice thickness is determined by the:
a. number of rows of detectors and the size of the detectors whose attenuation data gets combined b. pitch c. reconstruction interval d. collimation of the x-ray beam |
a. number of rows of detectors and the size of the detectors whose attenuation data gets combined
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The distance that the table travels between slices is called:
a. table increment b. collimation c. rotation d. reconstruction interval |
a. table increment
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A set of images is reconstructed with a 150 mm reconstruction FOV. Keeping all other parameters constant, a second set of images is reconstructed with a 300 mm reconstruction FOV, and then magnified so that the anatomical structures in the first and second set appear the same size. Which of the following statements is FALSE?
1. the resolution of the second set of images is better than the first set 2. the apparent noise in the second set of images is more pronounced than the first set 3. the patient dose of the first set of images is higher than the second set a. 1 & 2 b. 1 & 3 c. 2 & 3 d. 1, 2 & 3 |
d. 1, 2 & 3
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Which of the following is NOT directly proportional to mAs?
a. the mean energy of the x-ray photons leaving the tube b. the number of x-ray photons leaving the x-ray tube c. x-ray tube heating d. dose to the patient |
a. the mean energy of the x-ray photons leaving the tube
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Which of the following parameters causes helical slices to be reconstructed so they overlap?
a. table increment b. reconstruction interval c. pitch d. collimation |
b. reconstruction interval
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Which of the following is the expected result of a CT Number Calibration Test performed on a water phantom?
a. 0 (plus/minus) 3 b. 0 (plus/minus) 5 c. 1000 (plus/minus) 5 d. 100 (plus/minus) 3 |
a. 0 (plus/minus) 3
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On a conventional, or serial, CT scan, if we want 5mm slices with 1mm of overlap, the table increment should be _____mm
a. 10 b. 6 c. 4 d. 1 |
c. 4
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Which of the following parameters allows adjacent slices to be overlapped without increasing the dose to the patient?
a. reconstruction interval b. slice thickness c. table increment d. pitch |
a. reconstruction interval
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Which of the following can be changed retrospectively?
1. the slice thickness from an MDCT helical scan 2. the slice overlap from a single row detector scanner helical scan 3. the slice thickness from a single-row detector scanner helical scan a. 1 & 3 b. 1 & 2 c. 2 & 3 d. 1, 2 & 3 |
b. 1 & 2
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Which of the following values for pitch would stretch the x-ray helix the most?
a. 1.5 b. 1.0 c. 0.8 d. 0.5 |
a. 1.5
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The _______________ determines how penetrating the x-ray beam will be.
a. kVp b. rotation time c. mA d. pitch |
a. kVp
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Which of the following would be used in a high resolution study of the temporal bones?
1. reduced slice thickness 2. reduced reconstruction FOV 3. sharp reconstruction filter a. 1 only b. 2 only c. 3 only d. 1, 2 & 3 |
d. 1, 2 & 3
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Which of the following would be used to better visualize low contrast resolution?
1. decreased mAs 2. sharp reconstruction filter 3. narrow window width a. 1 only b. 2 only c. 1 & 2 d. 3 only |
d. 3 only
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For a given distance of coverage, which of the following is TRUE?
1. as reconstruction FOV increases, patient dose increases 2. as pitch increases, patient dose decreases 3. as slice thickness increases, patient dose decreases a. 1 only b. 2 only c. 3 only d. 2 & 3 |
d. 2 & 3
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___________ the window ______________ will make the image appear darker so that bony structures can be evaluated.
a. increasing, width b. decreasing, level c. decreasing, width d. increasing, level |
d. increasing, level
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