[gate-users] Attaching system

[Schmidtlein, Ross/Sloan-Kettering Institute]

Hi Martin,
 
I don't think you can define two independent detector systems.  It is my
understanding that layer level of the Cylindrical_PET system might do
what you want, but the fact that you are using smaller crystals in the
inner layer than in the outer one might make this feature useless to
you.  I think you have hit on a difficult limitation.  I can give you a
couple of quick ideas about what to do.
 
1)  The cleanest would be to add a new detector system to the GATE code,
but this would be quite difficult and time consuming.
 
2)  As an alternative you could build two simulation models and combined
them.  The first would make the outer detector ring the active detector
with the inner ring defined as a part of the phantom.  The second would
make the inner ring the active detector ring and ignore the outer one.
Singles files could then be built for each simulation and an external
coincidence sorter could be used to generated the coincidences.
However, binning the LOR's and sorting the coincidences, especially if
you are interested in count rate performance, could be difficult.  
 
Hope this helps,
 
ross
 
 
-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of
janecekm at mir.wustl.edu
Sent: Tuesday, February 08, 2005 2:35 PM
To: gate-users at lphe1pet1.epfl.ch
Subject: [gate-users] Attaching system


Hello everybody,

My name is Martin Janecek and I am part of a the Imaging Physics Group
at Washington University in St Louis. We are developing an
unconventional PET system consisting of a small detector ring - an
insert - placed inside of a large clinical scanner ring. The insert has
smaller (high-resolution) LSO detectors compared to the scanner
detectors. We want to simulate the system in GATE. A problem arises
however when we want to attach the detectors to a system. Does the GATE
code allow to attach two different resolution detectors in coincidence?
(We get an error message, telling us a volume is already attached when
trying to attach a second layer). The "attachment tree" seems to be of a
single branch, without the possibility to attach two different detector
blocks to one layer (Table 4.2 in the manual). 
 
Sincerely,
 
WashU Imaging Physics Group through Martin Janecek
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