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