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10 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the cause of image noise due to too few particles?
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quantum mottle
What is the minimum # of partilcles to have an effective V/Q scan? |
60,000
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What is contrast?
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The difference between counts in an object and in the background.
How is this expressed mathematically? |
Contrast = Imax - I min/Imax +Imin
where Imax = max count rate Imin = min count rate |
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What is the quanitative method for measuring resolution on a gamma camera?
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bar phantom
What is the ACR criterion for Tc99m planar bar resolution? |
2.5 to 2.9 mm
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What is a better quantitative method of measuring resolution?
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FWHM of line source
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What is the more complex method of resolution measurement called MTF?
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Modulation Transfer Function
spatial frequency response calculated in the frequency domain |
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A perfectly represented image would have an MTF of ___ while ___ indicated no record of the object
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A perfectly represented image would have an MTF of 1.0 while 0 indicated no record of the object
How is the total MTF calculated? |
It is the sum of the individual MTF's for each system component
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How is a ROI calculated?
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Area = # pixels X pixel height X pixel width
Why is background subtraction necessary? |
Counts are received above and below organ of interest and background subtraction attempts to correct for these unwanted counts
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What is the equation for calculating EF? (cardiac)
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(EDcts - Bkg) - (EScts - Bkg)/EDcts - Bkg = EF
will the result be higher or lower if you do not include background counts? |
it will be falsely low
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How is the time activity curve generated for kidney clearance?
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Counts in ROI = Max cts X e(-k-t)
where k is the rate constant for kidney clearance |
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In cardiac SPECT what does the bulls eye or polar map represent?
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Bulls eye is the apex of the heart and the area going out to the edges represent the lateral, inferior and septal walls of the heart
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