<HTML> <HEAD> <TITLE>Re: [Gate-users] voxellized phantom attenuation problem</TITLE> </HEAD> <BODY> Hi Ahmet, Could you send your script file and your phantom please ? I’ll try to reproduce the problem. (Sebastien what is that patch in 3.1.2 ?) Richard On 2/27/08 3:38 PM, "ayanas@mail.med.upenn.edu" <ayanas@mail.med.upenn.edu> wrote: <BLOCKQUOTE><TT> Dear Gate'rs I am observing a problem with a voxelized phantom (using compressed voxel) with gate-3.1.1. Here is what happens: I load a voxellized MCAT phantom as the attenuating medium. The source is a simple point source at the center of the phantom.   I am recording the un-scattered photons (140 keV) making out of the MCAT torso. Obervations: 1) When I make the material definitions of the all voxels as "Bone", (a uniform material made of bone) I get a sensible number of photons un-scattered. This is fine.. 2) When I make the material definitions of the all voxels as, "Lung" I, again,  get a sensible number of photons un-scattered. This is also fine.. 3) However, When I make the original MCAT definition, that is with Body (muscle),  Lung, Bone etc, I get a number of un-scattered photons much higher than the "All Bone" case making out of the MCAT torso; while I would expect to get a number between "All Bone" and "All Lung" case, (the densest material is the Bone, and the least dense is Lung). Has anybody observed such a behaviour? Any ideas/suggestions as to what my problem might be? I also saw a patch for gate 3.1.2 (patch_v3.1.2.tar.bin) with a mention to "compressed voxel capabilities". Does (Should) this patch apply also to gate 3.1.1 ? Thank you very much, ahmet. </TT></BLOCKQUOTE><TT> </TT> -- Richard Taschereau, Ph.D. Crump Institute for Molecular Imaging University of California Los Angeles 700 Westwood Plaza, A222 Los Angeles, CA 90095-1770 Phone: (310) 825-0697 Fax:     (310) 206-8975 email: RTaschereau@mednet.ucla.edu ---------------------------------------------------------- IMPORTANT WARNING: This email (and any attachments) is only intended for the use of the person or entity to which it is addressed, and may contain information that is privileged and confidential. You, the recipient, are obligated to maintain it in a safe, secure and confidential manner. Unauthorized redisclosure or failure to maintain confidentiality may subject you to federal and state penalties. If you are not the recipient, please immediately notify us by return email, and delete this message from your computer. ---------------------------------------------------------- </BODY> </HTML>