[Gate-users] GATE running problem--WARNING : positron found and photonID vector size 1

[Su, Yi]

Thanks a lot for the information. So exactly what triggers the warning message, when the positron escapes the 'world' or the phantom volume? Would these positrons interact with the detector and messing up the simulation? Right now I am seeing a couple of such warning messages per second.
Another question is if we are simulating a mouse PET scan using voxelized phantom/source, I assume the same volume is phantom and source at the same time, would this cause more such warning messages?

Thanks again.

Yi

From: yuxuan.zhang at di.mdacc.tmc.edu [mailto:yuxuan.zhang at di.mdacc.tmc.edu]
Sent: Friday, January 04, 2008 3:44 PM
To: Su, Yi
Cc: 'gate-users at lists.healthgrid.org'; gate-users-bounces at lists.healthgrid.org
Subject: Re: [Gate-users] GATE running problem--WARNING : positron found and photonID vector size 1


Usually it is because that the size of your phantom is not big enough therefore some positron can escape from the phantom without
annihilation. If there are not a lot of warning messages, (less than a few per second) then that's fine. Otherwise you need to
check your phantom and source definition. The common error is that the part of the source is outside the phantom.

yuxuan






"Su, Yi" <suy at mir.wustl.edu>
Sent by: gate-users-bounces at lists.healthgrid.org

01/04/2008 01:31 PM


        To:        "'gate-users at lists.healthgrid.org'" <gate-users at lists.healthgrid.org>
        cc:
        Subject:        [Gate-users] GATE running problem--WARNING : positron found and photonID vector size 1




Hi there,

I am running a GATE simulation and the following warning message keeps popping up:

[GateTrajectoryNavigator::FindAnnihilationGammasTrackID]  WARNING : positron found and photonID vector size: 1

Does anyone know what is going on, and what might be the problem? I am using Gate 3.1.2 and I am simulating an ecat system with a simple cylinder phantom and source.

Thanks a lot,

Yi
__________________________________________
Yi Su, PhD
Division of Radiological Sciences
Mallinckrodt Institute of Radiology
Washington University School of Medicine
Campus Box 8225
510 S. Kingshighway Blvd
St. Louis MO 63110
Phone: 314-362-8363
Fax:       314-362-9940
Email: suy at mir.wustl.edu




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