[Gate-users] Artefact in Interfile output

[Uwe Pietrzyk]

Hi Albert,

we had a similar problem, though not for simulating a SPECT system.
We finally found that using the "Ranlux64" consistently produced
artefacts, which become visible on long runs as yours. We have now
switched to the "MersenneTwister". Maybe you could give it a try.

Kind regards and best wishes

Uwe Pietrzyk
-----
On 03.11.2011, at 10:44, Albert Hirtl wrote:

> Dear Gate-users,
> 
> We are somewhat stuck :-) . We are trying to simulate a two-headed 
> SPECT-system with a very simple (cylindrical) water phantom inside. The 
> source is a gamma emitter with 140 keV. In principle things are fine, 
> however, there are some artefacts (?) in the interfile output. If you 
> please have a look at the attached image (need to zoom a little), you 
> see  some lines in the slices 9 and 73 (these are opposing SPECT-heads), 
> which I do not understand. They also appear at other slices (29-93, 
> 47-111, 59-123). Since these lines always occur in pairs, their origin 
> must probably be in the source somewhere. Has anybody ever seen such a 
> behaviour?
> 
> I also attached the relevant mac-files, maybe it is some trivial mistake 
> in one of the mac files. Any help would very much be appreciated!
> 
> Cheers,
> Albert
> 
> -- 
> Medizinische Universität Wien - Allgemeines Krankenhaus Wien
> Universitätsklinik für Nuklearmedizin
> Währinger Gürtel 18-20
> 1090 Wien
> Austria
> 
> Tel.: +43 (0) 1 / 40400 5545
> 
> Web:
> http://www.meduniwien.ac.at/user/albert.hirtl
> http://www.meduniwien.ac.at/moccamed/
> http://www.meduniwien.ac.at/nuklear/forschunglehre/physik/index.html
> 
> <100MBq_2headsSPECT.jpg><MainSPECT.mac><Activity.mac><CollimatorVPC45K.mac><Digitizer.mac><OutputTime.mac><PhantomSource.mac><Physics.mac><SystemGeometry.mac><albert_hirtl.vcf>_______________________________________________
> Gate-users mailing list
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/----------------------------------------------------------------------
Prof. Dr. Uwe Pietrzyk
Diplom-Physiker
Institut für Neurowissenschaften und Medizin / INM-4
Forschungszentrum Jülich GmbH
52425 Jülich
Tel: +49-2461-61 4763
Fax: +49-2461-61 2820 + 8229
Mobil: +49-162-103-4871
eMail: U.Pietrzyk at fz-juelich.de
http://www.fz-juelich.de/inm
&
Bergische Universität Wuppertal
Fachbereich C - Physik / D.08.01
Gaußstr. 20
42097 Wuppertal
Tel: +49-(0)202-439-3523
Fax: +49-(0)202-439-2811
eMail: Uwe.Pietrzyk at physik.uni-wuppertal.de
http://www.medizinphysik.uni-wuppertal.de
----------------------------------------------------------------------/








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