<HTML> <HEAD> <TITLE>Re: [Gate-users] Overlap between scanner geometry and Voxellized phantom</TITLE> </HEAD> <BODY> Hi Bosky, Overlapping volumes is a no-no in GATE/GEANT simulations.  I know some people have worked around that problem by splitting their phantom in smaller parts (you can have multiple voxellized phantoms). Richard On 5/15/08 8:48 AM, "Simon Stute" <gate.stute@gmail.com> wrote: <BLOCKQUOTE>Hi Bosky, We encountered exactly the same problem and the problem comes from Geant4. As I know the particles are "born" in a certain volume (here the phantom) and they move to a second volume only when they reach a boundary of the first one, so even if the particles are both in the phantom (i.e. first volume) and the second one (overlapping, here your scanner), they behave as they are in the first one. And unfortunately there is no solution ... except to resize your phantom if it's possible ... Cheers, Simon On Thu, May 15, 2008 at 5:14 PM, Ravindranath, Bosky <bosky@bnl.gov> wrote: <BLOCKQUOTE>Hello Gate users, I'm using voxellized phantoms to test my scanner performance, however due to the positioning of the scanner, there is bound to be overlapping regions between the scanner and the image that is read in as the phantom. The regions in the phantom that overlap with the scanner has material properties set to vacuum. When I run my simulations, I do not see any gamma interactions with the overlapping detector regions. Is there a way to work around this? I tried to define the scanner as a daughter of the phantom, GATE did not allow me to do that (I set the type as parameterized box matrix), I tried defining the phantom first and then the geometry, but the result was the same. Any suggestions appreciated. Thank you, Bosky _______________________________________________ Gate-users mailing list Gate-users@lists.healthgrid.org <a href="http://lists.healthgrid.org/mailman/listinfo/gate-users">http://lists.healthgrid.org/mailman/listinfo/gate-users</a> </BLOCKQUOTE> <HR ALIGN=CENTER SIZE="3" WIDTH="95%"><TT>_______________________________________________ Gate-users mailing list Gate-users@lists.healthgrid.org <a href="http://lists.healthgrid.org/mailman/listinfo/gate-users">http://lists.healthgrid.org/mailman/listinfo/gate-users</a> </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 intended recipient, please immediately notify us by return email, and delete this message from your computer. ---------------------------------------------------------- </BODY> </HTML>