Hi Peter The sensitivity varies by the phantom form, if you used a cylindrical phantom, the result will varies with respect to a spherical phantom (remember the geometrical efficiency) In a complete Gate simulation, is preferable to disable the optical option because the time of the simulation is so longer, so the information about the optical properties is no needed unless you will simulate the optical process. Gate take in count the hits (energy, position, time, ...) only in the crystalSD, so the optical fiber only is used like a dispersion volume (if you design it). Check the user's guide for more information, but I hope that the information given before will help you. Best regards <div class="gmail_quote">2009/2/21 <<a href="mailto:gate-users-request@lists.healthgrid.org">gate-users-request@lists.healthgrid.org</a>> <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Send Gate-users mailing list submissions to        <a href="mailto:gate-users@lists.healthgrid.org">gate-users@lists.healthgrid.org</a> To subscribe or unsubscribe via the World Wide Web, visit        <a href="http://lists.healthgrid.org/mailman/listinfo/gate-users" target="_blank">http://lists.healthgrid.org/mailman/listinfo/gate-users</a> or, via email, send a message with subject or body 'help' to        <a href="mailto:gate-users-request@lists.healthgrid.org">gate-users-request@lists.healthgrid.org</a> You can reach the person managing the list at        <a href="mailto:gate-users-owner@lists.healthgrid.org">gate-users-owner@lists.healthgrid.org</a> When replying, please edit your Subject line so it is more specific than "Re: Contents of Gate-users digest..." Today's Topics:   1. Simulation of a MicroPET II (Peter Stenk) ---------------------------------------------------------------------- Message: 1 Date: Fri, 20 Feb 2009 21:58:22 +0100 From: "Peter Stenk" <<a href="mailto:tigerspost@gmx.de">tigerspost@gmx.de</a>> Subject: [Gate-users] Simulation of a MicroPET II To: <a href="mailto:gate-users@lists.healthgrid.org">gate-users@lists.healthgrid.org</a> Message-ID: <<a href="mailto:20090220205822.14370@gmx.net">20090220205822.14370@gmx.net</a>> Content-Type: text/plain; charset="iso-8859-1" Hello! I'm very new to Gate and I have solved quite some problems on my own. I think geant4.9.1 and gate_v4.0.0 is installed properly by now and I try to simulate a MicroPET II scanner. I got some information about the geometry of this scanner so I think I built it correct. (30 rsectors, 3 submodules per rsector, 14x14 crystals with a diameter of 160mm and axial length of 49mm. The recursive_test says, no overlapping, everything fine)... The problem is, I did some tests and I got a sensitivity of less than 1% in the center of the scanner. But as far as my information tells, it should be around 2.26% I still did not find out, how to program the following part of the scanners description: "A barium sulphate reflector material was used between LSO elements leading to a detector pitch of 1.15 mm in both axial and transverse directions. Fused optical fibre bundles were made from 90 ?m diameter glass fibres with a numerical aperture of 0.56." Would this make such a great difference? How do I get the material information of the barium sulphate reflector material? Is there anyone who already did manage to simulate the MicroPET II? Thanks for your help. Peter P.S.: Here is an abstract that contains some information on the MicroPET II: <a href="http://www.iop.org/EJ/abstract/0031-9155/48/11/303" target="_blank">http://www.iop.org/EJ/abstract/0031-9155/48/11/303</a> -- Jetzt 1 Monat kostenlos! GMX FreeDSL - Telefonanschluss + DSL f?r nur 17,95 Euro/mtl.!* <a href="http://dsl.gmx.de/?ac=OM.AD.PD003K11308T4569a" target="_blank">http://dsl.gmx.de/?ac=OM.AD.PD003K11308T4569a</a> ------------------------------ _______________________________________________ Gate-users mailing list <a href="mailto:Gate-users@lists.healthgrid.org">Gate-users@lists.healthgrid.org</a> <a href="http://lists.healthgrid.org/mailman/listinfo/gate-users" target="_blank">http://lists.healthgrid.org/mailman/listinfo/gate-users</a> End of Gate-users Digest, Vol 33, Issue 15 ****************************************** </blockquote></div> -- e- + e+  ->  <~~*~~>