Hi Jinxia Guo, I already encountered this problem too ! I searched a lot but was not able to find the reason. But I found a solution, that is really really a do-it-yourself method ! Here is the trick: For your X sources, if you see that the first source to be weak is the Nth then insert a fictive source between the N-1th and the Nth sources. For me a fictive source is a source with no activity, and outside the field of view. Then launch your simulation again and see which is the next source to be weak. Then do these steps again until all your sources work correctly. I know this is annoying but it will probably work ! Good luck, Simon <div class="gmail_quote">On Tue, Apr 21, 2009 at 5:50 AM, jinxia guo <<a href="mailto:babygjx@gmail.com">babygjx@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi,dear users, Now I'am getting projection data with GATE4.0.0. In my mac file source.mac, there are 9 point sources in different positions. I checked the sourceID histogram with root and I found counts from a few sources are very low. After recontruction,sources with low counts cat't be seen. My source.mac and the sourceID histogram are as follows,Source 3 ,source 5,source 6,source 7,source 8,souce 9 seems no counts.I tried to use 6 Point sources,3 Point sources and even 2 Point sources ,the result is similar. I don't why it's so. Anyone knows about that? Hope your help. Thank you very much! ##########################Source One########################## /gate/source/addSource twogamma /gate/source/twogamma/setActivity 0.000001 Ci /gate/source/twogamma/setType backtoback /gate/source/twogamma/gps/particle gamma /gate/source/twogamma/gps/energytype Mono /gate/source/twogamma/gps/monoenergy 0.511 MeV /gate/source/twogamma/gps/type Point /gate/source/twogamma/gps/centre 0. 5. 0. mm /gate/source/twogamma/gps/angtype iso /gate/source/twogamma/gps/mintheta 90. deg /gate/source/twogamma/gps/maxtheta 90. deg /gate/source/twogamma/gps/minphi 0. deg /gate/source/twogamma/gps/maxphi 360. deg ##########################Source Two########################## /gate/source/addSource twogamma2 /gate/source/twogamma2/setActivity 0.000001 Ci /gate/source/twogamma2/setType backtoback /gate/source/twogamma2/gps/particle gamma /gate/source/twogamma2/gps/energytype Mono /gate/source/twogamma2/gps/monoenergy 0.511 MeV /gate/source/twogamma2/gps/type Point /gate/source/twogamma2/gps/centre 0. 5. 0. mm /gate/source/twogamma2/gps/angtype iso /gate/source/twogamma2/gps/mintheta 90. deg /gate/source/twogamma2/gps/maxtheta 90. deg /gate/source/twogamma2/gps/minphi 0. deg /gate/source/twogamma2/gps/maxphi 360. deg ##########################Source Three########################## /gate/source/addSource twogamma3 /gate/source/twogamma3/setActivity 0.000001 Ci /gate/source/twogamma3/setType backtoback /gate/source/twogamma3/gps/particle gamma /gate/source/twogamma3/gps/energytype Mono /gate/source/twogamma3/gps/monoenergy 0.511 MeV /gate/source/twogamma3/gps/type Point /gate/source/twogamma3/gps/centre 0. -5. 0. mm /gate/source/twogamma3/gps/angtype iso /gate/source/twogamma3/gps/mintheta 90. deg /gate/source/twogamma3/gps/maxtheta 90. deg /gate/source/twogamma3/gps/minphi 0. deg /gate/source/twogamma3/gps/maxphi 360. deg ##########################Source Fourth########################## /gate/source/addSource twogamma4 /gate/source/twogamma4/setActivity 0.000001 Ci /gate/source/twogamma4/setType backtoback /gate/source/twogamma4/gps/particle gamma /gate/source/twogamma4/gps/energytype Mono /gate/source/twogamma4/gps/monoenergy 0.511 MeV /gate/source/twogamma4/gps/type Point /gate/source/twogamma4/gps/centre 5. 5. 0. mm /gate/source/twogamma4/gps/angtype iso /gate/source/twogamma4/gps/mintheta 90. deg /gate/source/twogamma4/gps/maxtheta 90. deg /gate/source/twogamma4/gps/minphi 0. deg /gate/source/twogamma4/gps/maxphi 360. deg ##########################Source Five########################## /gate/source/addSource twogamma5 /gate/source/twogamma5/setActivity 0.000001 Ci /gate/source/twogamma5/setType backtoback /gate/source/twogamma5/gps/particle gamma /gate/source/twogamma5/gps/energytype Mono /gate/source/twogamma5/gps/monoenergy 0.511 MeV /gate/source/twogamma5/gps/type Point /gate/source/twogamma5/gps/centre 5. -5. 0. mm /gate/source/twogamma5/gps/angtype iso /gate/source/twogamma5/gps/mintheta 90. deg /gate/source/twogamma5/gps/maxtheta 90. deg /gate/source/twogamma5/gps/minphi 0. deg /gate/source/twogamma5/gps/maxphi 360. deg ##########################Source Six########################## /gate/source/addSource twogamma6 /gate/source/twogamma6/setActivity 0.000001 Ci /gate/source/twogamma6/setType backtoback /gate/source/twogamma6/gps/particle gamma /gate/source/twogamma6/gps/energytype Mono /gate/source/twogamma6/gps/monoenergy 0.511 MeV /gate/source/twogamma6/gps/type Point /gate/source/twogamma6/gps/centre 5. 0. 0. mm /gate/source/twogamma6/gps/angtype iso /gate/source/twogamma6/gps/mintheta 90. deg /gate/source/twogamma6/gps/maxtheta 90. deg /gate/source/twogamma6/gps/minphi 0. deg /gate/source/twogamma6/gps/maxphi 360. deg ##########################Source Seventh########################## /gate/source/addSource twogamma7 /gate/source/twogamma7/setActivity 0.000001 Ci /gate/source/twogamma7/setType backtoback /gate/source/twogamma7/gps/particle gamma /gate/source/twogamma7/gps/energytype Mono /gate/source/twogamma7/gps/monoenergy 0.511 MeV /gate/source/twogamma7/gps/type Point /gate/source/twogamma7/gps/centre -5. 0. 0. mm /gate/source/twogamma7/gps/angtype iso /gate/source/twogamma7/gps/mintheta 90. deg /gate/source/twogamma7/gps/maxtheta 90. deg /gate/source/twogamma7/gps/minphi 0. deg /gate/source/twogamma7/gps/maxphi 360. deg ##########################Source Eighth########################## /gate/source/addSource twogamma8 /gate/source/twogamma8/setActivity 0.000001 Ci /gate/source/twogamma8/setType backtoback /gate/source/twogamma8/gps/particle gamma /gate/source/twogamma8/gps/energytype Mono /gate/source/twogamma8/gps/monoenergy 0.511 MeV /gate/source/twogamma8/gps/type Point /gate/source/twogamma8/gps/centre -5. 5. 0. mm /gate/source/twogamma8/gps/angtype iso /gate/source/twogamma8/gps/mintheta 90. deg /gate/source/twogamma8/gps/maxtheta 90. deg /gate/source/twogamma8/gps/minphi 0. deg /gate/source/twogamma8/gps/maxphi 360. deg ##########################Source Ninth########################## /gate/source/addSource twogamma9 /gate/source/twogamma9/setActivity 0.000001 Ci /gate/source/twogamma9/setType backtoback /gate/source/twogamma9/gps/particle gamma /gate/source/twogamma9/gps/energytype Mono /gate/source/twogamma9/gps/monoenergy 0.511 MeV /gate/source/twogamma9/gps/type Point /gate/source/twogamma9/gps/centre -5. -5. 0. mm /gate/source/twogamma9/gps/angtype iso /gate/source/twogamma9/gps/mintheta 90. deg /gate/source/twogamma9/gps/maxtheta 90. deg /gate/source/twogamma9/gps/minphi 0. deg /gate/source/twogamma9/gps/maxphi 360. deg Best wishes, Jinxia Guo -- Jinxia.Guo School of Life, Huazhong Univ. of Sci. & Tech. Room 503, D11 Building 1037 Luoyu Road, Wuhan 430074, China Tel & Fax:+86-27-8779-2294 _______________________________________________ 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> </blockquote></div>