[Gate-users] Simulation time for Depth of interaction in PET

[Leo Read]

Hello all,

I'm setting up a simulation to study effect of DOI on point source
resolution in a PET detector cylinder based on the PET benchmark code. I'm
finding that my simulations are taking a long time.

I tried to turn on/off different processes being modeled in physics.mac and
found that commenting out the 'eMultipleScattering' lines in the macro
seems to reduce the simulation time significantly. Also, the range of the
hits for this process are not very large (typically < 10^-2 mm), which
suggests to me that simulating this process is not very important.

Changing the F18LineSource from a e+ emitter to a back-to-back gamma source
also helped a lot.

I have two questions:
1) What exactly is 'eMultipleScattering' simulating? The user guide
description was not too clear to me.
2) If you were trying to just investigate the effect of DOI on resolution,
are there any other changes you would make to the PET benchmark code to
save simulation time?

Thanks for your time and comments!
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