cristiancj88 at hotmail.com
Sun May 1 20:56:20 CEST 2011
I'm simulating a SPECT system and I have some doubts regarding the output ascii data files. I've included spatial resolution, quantum efficiency and dead time and, from all the data files produced I focus on two of them: "Singles.dat" and "SinglesSpblurring.dat", which have a different number of entries. As an example, I've run a short simulation which has produced 2305 entries in the "Singles" file and 2344 in the "SinglesSpblurring" file. When I include quantum efficiency these two values remain the same, even if I set "setUniqueQE 0.", in which case I would expect to have no entries. In addition, if I also include a dead time, the number of entries in the "Singles" file is 2188, whereas the number of entries in the "SinglesSpblurring" file doesn't change (it's still 2344, as before). My questions are:
1) Why do we have a different number of entries in the "Singles" and "SinglesSpblurring" files?
2) Why adding QE doesn't change the number of entries in this case? How can I then reduce the detected number of photons?
3) Why the dead time affects the "Singles" file but not the "SinglesSpblurring" file?
Below I've copied the lines I use to produce the digitizer. I would really appreciate your help.
# D I G I T I Z E R
# ENERGY BLURRING
/gate/digitizer/Singles/blurring/setEnergyOfReference 140. keV
# SPATIAL BLURRING
/gate/digitizer/Singles/spblurring/setSpresolution 1.54 mm
# THRESHOLD ELECTRONICS
/gate/digitizer/Singles/thresholder/setThreshold 20. keV
/gate/digitizer/Singles/upholder/setUphold 190. keV
# DEFINE TRANSFER EFFICIENCY FOR EACH LAYER
# DEFINE LIGHT YIELD FOR EACH LAYER
# DEFINE QUANTUM EFFICIENCY OF THE PHOTODETECTOR
#/gate/digitizer/Singles/deadtime/setDeadTime 0.1 ms
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