[Gate-users] Fwd: Benchmark disagreements

[Sebastien JAN]

Dear Users,

About these questions concerning the SPECT benchmark decrepencies, the 
OpenGATE collaboration will execute the two benchmarks and will produce 
a new sets of official results ASAP.
We thank the users for all remarks, comments and for this active 
collaboration.

Regards
Sebastien JAN

> Quite interesting and a little surprised to me.
>
> I tend to agree with Sebastein that the difference is due to
> physics processes not simply due to statistics. Then to further understand
> what is the difference is essential for us - Gate users.
>
> Here is a list I can think out for a check:
>
>                recommended results             current version
>
> 1,versions (GATE 1, 2? <- Geant4 4, 5? )    GATE 3 <- Geant4 8
> 2,physics list    standard or lowenergy?  
>   process         Compton only?             Compton, Rayleigh?
> 3,thresholds      e, gamma for different processes
>
> Assuming all of above 2,3 are the same for two GATE versions, then go 
> to dig out:
>
> What has been changed in Geant4 physics process?
>
> One can compare by
> turning on Compton, off Rayleigh
> turning off Compton, on Rayleigh
>
> in two different GATE (G4) versions
> to see which process caused the difference.
>
> Is the difference reasonable?
>
> If yes, we may try to validate the new GATE results and trust it.
>
> if not, dig deeper into Geant4. Does GATE use default cross section 
> table in G4?
> Can we try other options in G4?
>
>
> So far, that's it.
>
> Hope it helps.
>
>
> Yu Chen, Ph.D.
> University of Massachusetts Medical School
> Division of Nuclear Medicine
> 55 Lake Avenue North
> Worcester, MA 01655-0243
> Phone:  (508) 856-6123
> Fax:    (508) 856-4572
>
>
>
> -----Original Message-----
> From: gate-users-bounces at lists.healthgrid.org on behalf of Antigoni Divoli
> Sent: Tue 7/3/2007 9:36 AM
> To: gate-users at lists.healthgrid.org
> Subject: [Gate-users] Fwd: Benchmark disagreements
>
> Dear all,
> about a month ago I posted a message regarding some discrepancies found
> in the results of the SPECTbenchmark when compared with the suggested
> results in the gate web-page. Some people reported similar
> discrepancies. We took this issue a bit further 'privately' with
> Sebastien and the end point was that could be due to different version
> of G4 used by 'us' and that used to obtain the recommended results.
>
> Attached you can find our conversation which might be of interest to
> you.
> If you have any comments/suggestions will be highly appreciated.
>
> Regards
>
> Antigoni
>
> The Institute of Cancer Research: Royal Cancer Hospital, a charitable 
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