[Gate-users] Different coincidence rate - CPU vs GPU

[Zakarumit.Z at seznam.cz]

Hi,

I would like to ask the community if anyone witnessed a difference between 
the coincidence rate when running the simulation on CPU and GPU? I have got 
a PET geometry with voxelized phantom and when using CPU, I am getting 
coincidence output file of size around 700 kb from 1M  primaries. When 
running the same geometry on GPU with the same number of primaries, I am 
getting files of 2 MB, i.e. + roughly 185 % detected coincidences.
Can anyone tell me what can be the cause and how to fix it?

I am using those source definitions if that helps:
CPU:
/gate/source/addSource zdroj voxel
/gate/source/zdroj/reader/insert image
/gate/source/zdroj/imageReader/translator/insert linear
/gate/source/zdroj/imageReader/linearTranslator/setScale 1. Bq
/gate/source/zdroj/imageReader/readFile phantom_data/SPECT128.h33
/gate/source/zdroj/setType backtoback
/gate/source/zdroj/gps/particle gamma
/gate/source/zdroj/gps/energytype Mono
/gate/source/zdroj/gps/monoenergy 0.511 MeV
/gate/source/zdroj/setPosition -28.2590976 -28.2590976 -28.259072 cm
/gate/source/zdroj/gps/angtype iso

GPU:
/gate/source/addSource zdroj GPUEmisTomo
/gate/source/zdroj/attachPhantomTo pacient
/gate/source/zdroj/setGPUBufferSize 15000000
/gate/source/zdroj/setGPUDeviceID 1
/gate/source/zdroj/reader/insert image
/gate/source/zdroj/imageReader/translator/insert linear
/gate/source/zdroj/imageReader/linearTranslator/setScale 1. Bq
/gate/source/zdroj/imageReader/readFile phantom_data/SPECT128.h33
/gate/source/zdroj/setType backtoback
/gate/source/zdroj/gps/particle gamma
/gate/source/zdroj/gps/energytype Mono
/gate/source/zdroj/gps/monoenergy 0.511 MeV
/gate/source/zdroj/setPosition -28.2590976 -28.2590976 -28.259072 cm
/gate/source/zdroj/gps/angtype iso

Best regards,

Jiri Ters

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