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12 Cards in this Set

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  • Back
  • 3rd side (hint)
What is the only regulation from NJ and NRC regarding QC?
Dose calibrator
What is the most effective test as far as sensitivity for evaluating a gamma camera's imaging ability?
Planar extrinsic floods
What is the main reason an intrinsic flood is done?
To R/O collimator and/or camera artifact causes
List 7 reasons or changes that cause uniformity degradation
1. poor gain alignment
2. PMT failure
3. count rate increases
4. improper peak
5. Spatial non-lineararities
6. crystal defects
7. environmental conditions
What is a moire pattern?
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
What is the allowable deviation for spatial registration?
2 mm
What is the importance of the initial QC tests on a SPECT camera?
It establishes the baseline reference for all future QC
non-uniformity of SPECT camera will result in what artifact?
bull's eye
How is uniformity maintained on a camera?
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
How is SPECT uniformity QC done?
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
When the cylinder is imaged in the SPECT QC what is the image suppossed to look like?
flat profile
What does it mean if it is curved downward or upward?
downward: under correction for attenuation
upward: over correction for attenuation
Why is COR necessary and what does it do?
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