[Gate-users] Regular Parameterization Error with Geant4 v10

[David Sarrut]

Hello,

To my knowledge, RegularParameterization with flag skipEqualMaterials is
still buggy (it should be disabled: if someone know this code, please
propose a pull request to correct or disable this option).

Use either:
- ImageNestedParametrisedVolume : simple conventional navigator, similar to
regular, (slightly faster)

- ImageRegionalizedVolume as proposed by Maxime. It could be 3-4 times
faster in some cases but it depends on what you are storing during the
simulation. If it is a dose map, take care to the statistical
uncertainties. If you are only interested in particle outgoing the volume
(for imaging for example), it is safe to use. Of course, the speed up
depends on the voxelized volume (faster if lot of similar material).

Doc is here:
http://wiki.opengatecollaboration.org/index.php/Users_Guide_V8.0:Voxelized_Source_and_Phantom#Nested_parameterization_method

David


On Fri, Feb 10, 2017 at 4:45 PM, Maxime Chauvin <maxime.chauvin at inserm.fr>
wrote:

> Hello Nicolas,
>
> I had the same problem as you and couldn’t fix it. On the other hand there
> is a even more efficient way  using
> ImageRegionalizedVolume. It will further speed up the simulation
> especially if your geometry has a lot of common voxel
> and you will get rid of this warning.
>
> Cheers,
>   Maxime
>
> On 10 Feb 2017, at 14:41, Triltsch, Nicolas <nicolas.triltsch at tum.de>
> wrote:
>
> Hello,
>
> I tried to speed up my simulation by choosing Regular Parameterization
> (with flag skipEqualMaterials to 1) instead of Nested Parameterization,
> because my Volume got a lot of voxels with the same material. It did indeed
> speed up the simulation by a factor of 15, but some projections of my CT
> simulation failed (error: segmentation fault; crash).
>
> Now I saw that during the initialization phase of gate it states the
> following:
>
> *### WARNING ### setSkipEqualMaterials at false !! The Geant4 method is
> not safe since the release 9.5 - Need to be fixed*
>
> I am pretty sure that this warning is somehow connected to the warning.
> Does anyone know if there had been a bug fix for Geant4 v10.2.2?
>
> In the appendix there is a screenshot of the error.
>
> Cheers,
> Nico
>
> --
> B.Sc. Nicolas Triltsch
> Masterand
>
> Technische Universität München
> Physik-Department
> Lehrstuhl für Biomedizinische Physik E17
>
> James-Franck-Straße 1
> 85748 Garching b. München
>
> Tel: +49 89 289 12591 <+49%2089%2028912591>
> nicolas.triltsch at tum.dewww.e17.ph.tum.de
>
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-- 
David Sarrut, Phd
Directeur de recherche CNRS
CREATIS, UMR CNRS 5220, Inserm U1206
Centre de lutte contre le cancer Léon Bérard
28 rue Laënnec, 69373 Lyon cedex 08
Tel : 04 78 78 51 51 / 06 74 72 05 42
http://www.creatis.insa-lyon.fr/~dsarrut
_________________________________
 "2 + 2 = 5,  for extremely large values of 2"
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