<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hello,<div> </div><div>Geant4 deals with boundaries by stepping onto them, and then stepping away again, so yes, each interface will cause a mandatory step. If this is causing problems, try adding the line: </div><div> </div><div><div style="margin: 0px; font-size: 11px; font-family: Menlo; ">/gate/actor/dose/stepHitType random</div></div><div style="margin: 0px; font-size: 11px; font-family: Menlo; "> </div><div style="margin: 0px; ">(assuming you have a dose actor called 'dose'). This tells GATE to deposit energy from each step at a random point along the step, and ought to remove any artefacts from boundaries/step limits.</div><div style="margin: 0px; "> </div><div style="margin: 0px; ">Hope that helps,</div><div style="margin: 0px; ">Andrew</div><div style="margin: 0px; "> </div><div style="margin: 0px; "> </div><div><div><div>On 12 Aug 2013, at 11:00, <<a href="mailto:gate-users-request@lists.opengatecollaboration.org">gate-users-request@lists.opengatecollaboration.org</a>></div><div> wrote:</div> <blockquote type="cite">Send Gate-users mailing list submissions to <a href="mailto:gate-users@lists.opengatecollaboration.org">gate-users@lists.opengatecollaboration.org</a> To subscribe or unsubscribe via the World Wide Web, visit http://lists.opengatecollaboration.org/mailman/listinfo/gate-users or, via email, send a message with subject or body 'help' to gate-users-request@lists.opengatecollaboration.org You can reach the person managing the list at gate-users-owner@lists.opengatecollaboration.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Gate-users digest..." Today's Topics: 1. Re: the consequences of interface in particle tracking (Hermann Fuchs) ---------------------------------------------------------------------- Message: 1 Date: Mon, 12 Aug 2013 11:00:45 +0200 From: Hermann Fuchs <hermann.fuchs@meduniwien.ac.at> To: gate-users@lists.opengatecollaboration.org Subject: Re: [Gate-users] the consequences of interface in particle tracking Message-ID: <1376298045.8816.3.camel@strahlen41.strahlen.meduniwien.ac.at> Content-Type: text/plain; charset="utf-8" Hello As far as I know each material border, be it a voxel(border) in a voxelised phantom ar a conventional geometry imposes an mandotory step. This is coming from the underlying geant4. and has something to do with how particles are tracked. Cheers, Hermann On Fri, 2013-08-09 at 15:21 +0000, Chiavassa Sophie wrote: <blockquote type="cite">Hello, Using GateV6.2 we obtained strange results for geometries with interfaces (like voxelized geometry). To investigate this point, we performed very simple simulation (main.mac): - Mono energetic photon source (80 keV) and a dose actor in a box of water (cuve) We compare results with the same box adding a second water box (Interface), daughter of the first water box (cuve) (interface water/water). Theoretically, results should be similar. In fact we obtain a peak in each interface (results.jpg). Various hypothesis were explored: - Same results were obtain for all Electromagnetic processes and models. - Global Edep is similar with and without interfaces. - Same results were obtain with Geant4 (geant4.zip) Moreover, when max step size parameter is reduced, we obtain similar peak at each step. It seems that interface create an artificial step in the simulation process. Could you reproduce this behavior from your side ? Results obtained with and without interfaces should be similar for homogeneous media. What do you think about that ? Best regards Sophie Chiavassa Radiophysicienne Service de physique m?dicale Centre de Lutte Contre le Cancer Nantes Atlantiques ? Ren? Gauducheau Site Hospitalier Nord Bd J. Monod 44805 ST HERBLAIN CEDEX 0240679963 cid:193052914@09082012-3151 _______________________________________________ Gate-users mailing list Gate-users@lists.opengatecollaboration.org http://lists.opengatecollaboration.org/mailman/listinfo/gate-users </blockquote> -- ------------- DI Hermann Fuchs Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology Department of Radiation Oncology Medical University Vienna W?hringer G?rtel 18-20 A-1090 Wien Tel. + 43 / 1 / 40 400 7271 Mail. hermann.fuchs@meduniwien.ac.at -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20130812/70d943e3/attachment-0001.html> -------------- next part -------------- A non-text attachment was scrubbed... Name: image001.jpg Type: image/jpeg Size: 13299 bytes Desc: image001.jpg URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20130812/70d943e3/attachment-0001.jpg> ------------------------------ _______________________________________________ Gate-users mailing list Gate-users@lists.opengatecollaboration.org http://lists.opengatecollaboration.org/mailman/listinfo/gate-users End of Gate-users Digest, Vol 87, Issue 13 ****************************************** </blockquote></div> </div></body></html>