[gate-users] about the sources

[Schmidtlein, Ross/Sloan-Kettering Institute]

Hi Yuxuan,
 
The F18, O15, and C11 sources do include the positron range effect.
These sources use a polynomial fit of the respective spectrums to shoot
a positron with its energy sampled from that spectrum.  As far as
angular limitations go, I think you are correct in that only the source
particle is limited in its direction of travel so the utility of that
command is limited.  Hope that helps.
 
ross
 
 
-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of
yuxuan.zhang at di.mdacc.tmc.edu
Sent: Monday, December 12, 2005 4:30 PM
To: GATE feedback and helpline for Users
Subject: Re: [gate-users] about the sources



Hi, 

I need to do some simulation about the resolutions of PET. 
There are three types of sources in GATE: backtoback gamma 
pairs; predefined F18, O15 and C11 positron sources, and 
all kinds of isotope sources defined in Geant4. 

According to the GATE developer, the positron sources of 
F18, O15 and C11 are the only sources that simulate the acolinearity. 
However, using these three sources, the positron range effect are 
not included. If we use the isotope sources, then the acolinearity 
are not include. So is there anybody knows a way that I can 
include the positron range and acolinearity in one simulation 
setup? 
  
Also according to the GATE manual, there are some command like 
/gate/source/gps/mintheta 
/gate/source/gps/maxtheta 
/gate/source/gps/minphi 
/gate/source/gps/maxphi 
can be used to limit the range of the direction of the source 
which can reduced the simulation time if the detector angle are 
small. Using these commands with backtoback gamma source is very 
helpful. However, if I am using the positron or isotope sources, 
looks like there's no physics meaning to using these commands, 
since the direction of the gamma ray pairs should be independed 
from the original particles. If this is true, then is there any 
other method to set the range limit to direction of the gamma ray 
pair? 


Yuxuan
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