[gate-users] WARNING : positron found and photonID vector size:1

[Jin Zhang]

Hi Theo:

Yes, I think to have electron range cuts would help but I doubt if the 
simulation results would be very different. As I guess the warning means 
that the positron is out of the camera's field of view and thus it's 
annihilation photons would not be counted as coincidence events.  But 
they do contribute to Random and Scatter counts though. Pls correct me 
if I am wrong.
My suggestion is that a few of these warnings would be OK, if you didn't 
get tons of it, which reduces your actual activity dose.
Good luck and I want to hear more about this as well.

Jin

Mutanga Theodore wrote:

>Hi Jin,
>I did as you suggested and I still had some warnings, maybe I have to set
>some electron range cuts instead ?
>What do you think ?
>Has anyone been doing measurements in air ?
>Theo
>
>
>
>  
>
>>That is because of the much longer positron range in air, which is about
>>170 cm for F18. But the average range in water is only 0.06 cm (F18). If
>>you can use a small water sphere to hold your source, it may help to
>>stop the warning message.
>>
>>Jin
>>
>>Mutanga Theodore wrote:
>>
>>    
>>
>>>Hello Gaters,
>>>
>>>I had a setup for simulating and measuring the resolution of the
>>>scanner,since the measurements had to be done in Air, I defined a phantom
>>>which is a cylinder the same size as the inner diamter of the scanner.
>>>
>>>When I set the material as Air I have this warning messages
>>>
>>>:[GateTrajectoryNavigator::FindAnnihilationGammasTrackID]  WARNING :
>>>positron found and photonID vector size: 1
>>>
>>>I don't really know what this means but when I use Water as the medium in
>>>the phantom I don't get this error , how does it affect my simulation ?
>>>
>>>Cheers
>>>
>>>Theodore
>>>
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>>>      
>>>
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>>
>
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