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12 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the only regulation from NJ and NRC regarding QC?
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Dose calibrator
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What is the most effective test as far as sensitivity for evaluating a gamma camera's imaging ability?
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Planar extrinsic floods
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What is the main reason an intrinsic flood is done?
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To R/O collimator and/or camera artifact causes
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List 7 reasons or changes that cause uniformity degradation
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1. poor gain alignment
2. PMT failure 3. count rate increases 4. improper peak 5. Spatial non-lineararities 6. crystal defects 7. environmental conditions |
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What is a moire pattern?
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interplay of bar phantom with collimator, or too small of a matrix can create lines on image that are a misrepresentation of reality
how do you fix it? |
use larger matrix
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What is the allowable deviation for spatial registration?
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2 mm
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What is the importance of the initial QC tests on a SPECT camera?
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It establishes the baseline reference for all future QC
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non-uniformity of SPECT camera will result in what artifact?
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bull's eye
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How is uniformity maintained on a camera?
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a correction "map" is created by a high count rate flood (30 million+) and creates a count correction for every pixel in the matrix
What is the mathematical relationship for this? |
Correction factor= (means flood counts/pixel)/counts in any pixel
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How is SPECT uniformity QC done?
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radioactive material is put into a water filled cylinder to reach count rate of 20-30k cps, imaged with 128 stops in 360 deg rotation, 200k per stop,
images are visually inspected for artifacts |
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When the cylinder is imaged in the SPECT QC what is the image suppossed to look like?
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flat profile
What does it mean if it is curved downward or upward? |
downward: under correction for attenuation
upward: over correction for attenuation |
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Why is COR necessary and what does it do?
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AOR will differ from COR so correction factor is put into place
How much of a COR deviation will show up on the final image? |
1/2 pixel
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