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CT numbers range from
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0 - 1000
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The number of photons detected on a CT scanner depends on:
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Detector efficiency, photon flux, patient size and slice thickness
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Another name for a "Small Field of View" is:
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Targeting
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All of the following describe the Standard Deviation of CT Quality Control test:
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Measurement: take a scan, reconstruct the image, examine the ROI, measure the average CT number; Expected results: typical values are in the range of 2-7 CT numbers. Water filled plastic container is about 20 cm in diameter. The standard deviation should not be very large.
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CT X-ray tube output intensity depends on:
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Beam filtration, kVp, mAs but not collimation
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Standard Deviation of CT
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Daily
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High Contrast Resolution
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Monthly
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Average CT Number of Water
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Daily
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Low Contrast Resolution
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Monthly
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Accuracy of Distance: Measuring Device
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Annually
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Contrast resolution is the ability of an imaging system to demonstrate small changes in tissue contrast
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True
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Thinner slices mean less scatter and better contrast
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True
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CT noise levels depend on:
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Matrix size, slice thickness algorithm, scatter radiation, object size, and photon flux to the detector and electronic noise
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Smaller voxels mean less radiation per voxel
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True
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Increasing slice width degrades spatial resolution
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True
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