[Gate-users] scatter extract from voxelized phantom with different voxel size

[Wei ZHAO]

Dear GATE user,
 
I am using GATE to do a MC-based scatter correction for Cone-beam CT imaging. I have imported a thorax 3D data set using voxelized phantom format and want to investigate influence of the phantom downsampling on the extracted scatter signal. The voxelized phantoms are 32x32x16, 64x64x16,128x128x16,256x256x16 grids with 8.8x8.8x11.2mm^3, 4.4x4.4x11.2mm^3,2.2x2.2x11.2mm^3,1.1x1.1x11.2mm^3 voxel size respectively. Since the phantom size is the same (with different voxel size), the extract scatter shouldn't change significantly. However, the final scatter have dramatic change. This may related to HOW GATE RETRIEVAL SCATTER USING VOXELPHANTOMSD? Does this dependent on voxel size?
 
I have used the below command to record scatter events.
 /gate/hof_brain/attachVoxelPhantomSD
the result is the smaller voxel size is, the smaller scatter signal I got.
 Can anyone help me sort this out? I will really appreciate.
 
Thank you very much!
Best regards
Wei
 
this is my voxelized phantom script:
--------------------------------------------------------------------------------------------------
/gate/world/daughters/name hof_brain
/gate/world/daughters/insert                             regularMatrix
#/gate/world/daughters/insert                            fictitiousVoxelMap
/gate/hof_brain/geometry/insertReader interfile
/gate/hof_brain/interfileReader/insertTranslator range
/gate/hof_brain/interfileReader/rangeTranslator/readTable range_atten_brain_0.dat
/gate/hof_brain/interfileReader/rangeTranslator/describe 1
/gate/hof_brain/interfileReader/readFile brain_phantom.h33
/gate/hof_brain/placement/setTranslation  0. 0. 0. mm
/gate/hof_brain/placement/setRotationAxis 1 0 0
/gate/hof_brain/placement/setRotationAngle -90 deg
/gate/hof_brain/attachVoxelPhantomSD
#/gate/phantom/setSkipEqualMaterials                      0
#/gate/phantom/setFictitiousEnergy                       111. keV
#/gate/phantom/setGammaDiscardEnergy                     0.1 keV
------------------------------------------------------------------------------------------------------

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20131210/cc2f01ec/attachment.html>