[Gate-users] Zero Binned Photons when Using ARF Tables

[Miriam Dixon]

Hi all,

I am hoping to decrease the time of my SPECT simulations by using ARF
Tables, as suggested in the GATE documentation. This takes three steps: 1)
generate the ARF data, 2) calculate the ARF tables, and 3) use the ARF
tables. The output of each step is used in the following step from its
location in the output folder.
When I run a quick test (activity set to 1MBq), step one and two seem to
work ok, with the final output for step two being:

Total Number of Binned Photons (not necessarily detected in the energy
window chosen) 139
[Core-0] End of macro mac/ARFTable_Calculate.mac
 ----------------------------------------------------------------------------------------------
 Writing ARF Table systems/SPECTheadARFTable_0 to file
output/ARFSPECTBench.bin at position 17...[OK] : 8388672 bytes
 All ARF tables have been saved to binary file
 output/ARFSPECTBench.binGraphics systems deleted.
Visualization Manager deleting...

This all looks fine to me. The problem is that at the start of step three,
the summary of what is in the ARF Table states:
Total Number of Binned Photons (not necessarily detected in the energy
window chosen) 0

Where did the 139 photons from the end of step 2 go? I have checked, and
the name of the file that is being saved at the end of step 2 is definitely
the file being called in step 3. I have also tried playing with various
parameters in the files but none of them change the number of binned
photons being read in step 3. Does anyone have any experience with the ARF
technique, and are able to shed some light on what might be the problem?

I have included a summary of key lines of code below, if it is of interest.
Cheers,
Miriam

Step 2:
# Geometry SPECT
/control/execute mac/spect_head.mac
/gate/SPECThead/placement/setRotationAxis 0 1 0
/gate/SPECThead/placement/setRotationAngle 90 deg

/gate/systems/SPECThead/arf/setARFStage computeTables

/control/execute mac/spect_collimator_lehr.mac
# ARF Digitizer
/gate/systems/SPECThead/ARFTables/setEnergyDepositionThreshHold 3. keV
/gate/systems/SPECThead/ARFTables/setEnergyDepositionUpHold 200 keV
/gate/systems/SPECThead/ARFTables/setEnergyResolution 0.1
/gate/systems/SPECThead/ARFTables/setEnergyOfReference 140. keV
/gate/systems/SPECThead/ARFTables/setDistanceFromSourceToDetector 47.8 cm

#
# NOW WE ARE  READY TO COMPUTE THE ARF TABLES
#
/gate/systems/SPECThead/ARFTables/ComputeTablesFromEnergyWindows
mac/ARFData.txt
/gate/systems/SPECThead/ARFTables/list
 # SAVE ARF TABLES TO A BINARY FILE FOR PRODUCTION USE
/gate/systems/SPECThead/ARFTables/saveARFTablesToBinaryFile
output/ARFSPECTBench.bin

Step 3:
# Geometry SPECT
/control/execute mac/spect_head.mac
/gate/SPECThead/placement/setRotationAxis 0 1 0
/gate/SPECThead/placement/setRotationAngle 90 deg

/gate/systems/SPECThead/arf/setARFStage useTables

/control/execute mac/spect_collimator_lehr.mac
/control/execute mac/spect_digitizer_Tc99m.mac
/gate/systems/SPECThead/setProjectionPlane 7.8 cm
/gate/systems/SPECThead/attachToARFSD
/gate/systems/SPECThead/ARFTables/loadARFTablesFromBinaryFile
output/ARFSPECTBench.bin

#Phantom, Physics, Initialize, Source, Random and Run follow, set up as I
normally have them
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/pipermail/gate-users/attachments/20200625/aeace3fa/attachment-0001.html>