[Gate-users] Gate 3.1.2 vs Gate 4.0

[Nicolas Karakatsanis]

Hi Ross and Sebastian

could you please specify which Geant4 version you are using for Gate 
3.1.2 and 4.0 versions?
Geant4 low energy models have been revised lately.

Best regards
Nicolas

Seb wrote:
> Hi Ross,
>
> First, I would like to say that nothing in the code was changed 
> between version 3.1.2 et 4.0, regarding the physical processes when 
> you use the classical navigator. This is why I can't give you a direct 
> and clear solution.
> Could you check the globalPos (X-Y-Z) variables between the 2 versions 
> ? Is there a difference in this event distribution ?
>
> Cheers
> Seb
>>
>> I'm working with Hyejoo on this and we have confirmed that we are 
>> using the correct low EM processes. The differences that we have seen 
>> in the sinograms for identical models and input parameters are 
>> dramatic (I've attached the figures to this email, sinogramS top and 
>> sinogramTheta bottom).  These differences seem too large to be due to 
>> a refinement in the low energy model associated with the new release 
>> of G4.  We are going to perform another GATE run with a simple 
>> asymmetric phantom (I'm thinking an elliptical cylinder phantom with 
>> a 4:1 hot cylinder offset) and run it with both standard GATE shapes 
>> and as a voxelized phantom and see if we can pin down the culprit.  
>> Any ideas on your side?
>>
>> Cheers,
>>
>> ross
>>
>
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