Image Quality in Nuclear Medicine (Erin) Flashcards
In NM does longer acquisition time increase or reduce noise?
Reduces noise
In NM studies does increased activity of the radiopharmaceutical increase of reduce noise?
Reduces noise
Does increasing the sensitivity of the gamma camera increase of reduce noise
Reduces noise
Does increased sensitivity of the gamma camera increase or decrease SR and contrast
Decreases
What is the effect of a thicker scintillation crystal on spatial resolution
Decreases spatial resolution
What is the effect of a smaller number of PMT on spatial resolution?
Reduced spatial resolution
What is the effect of large diameter holes in the collimator on image SR
Reduces SR
What is the effect of short holes in the collimator on image SR
Reduces SR
What is the effect of patient motion on image SR
Reduces SR
What is the effect of imaging deeper structures on SR
Decreases SR
What is the effect of increased scattered radiation on SR
Decreases SR
What is the effect of a larger patient/detector distance on SR
Decreases SR
What is the effect of long length holes in the collimator on SR
Improves SR
However increased noise
What is the effect of decreased scattered radiation on image SR
Improves SR
What is the effect of smaller diameter holes in the collimator on image SR
Improves SR
However also increases noise
What is the effect of a thinner scintillation crystal on SR
Improves SR
In PET:
What is the dead time
Time following detection in which detector insensitive to further incident gamma photons calculated and counts corrected for
In NM what is the effective a smaller matrix on SNR
Better SNR
What is the typical matrix size in gated cardiac imaging
64x64
What is the typical matrix size in dynamic imaging
128x128
or 256x256
What is the typical matrix size used in static imaging
256x256
In PET what is the effect of a wider photo peak acceptance window on contrast and noise
Decreases noise
Decreases contrast
In PET how does thickness of the scintillation crystal affect SR
Thicker crystal = poorer SR
Thinner crystal = improved SR
Why is noise less in PET than SPECT
PET has a much higher count rate - so noise is less of an issue
Pet vS SPECT: which has more noise?
SPECT
PET VS SPECT: Which has better resolution?
PET