<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body >Dear Gate-users, <div>I’m trying to simulate my SPECT system using Angular Response Functions (ARFs). I followed the 3 steps described in the “User Guide v7.0”. First I generated the ARF tables computing a rectangular source of Tc99m (140 keV) located at the center of FOV but I don’t understand how much is important the size of the source and the distance from the SPECThead. In the third step (use of the ARF tables), following the example provided in the folder /examples/example_ARF/ useARFTables.mac, I created only the main headvolume SPECThead, made of air, without any daughters (for example, crystal, shielding,…). The problem is that proceeding in this way I can’t obtain a meaningful image. Could you please tell me what am I doing wrong?</div><div><br></div><div> I also noticed that in the macro example, useARFTables.mac, there is no specification of the energy window. Is this correct?</div><div> </div><div>Could you also please tell me the meaning of the following commands?</div><div><br></div><div> /gate/source/ARFSource/gps/ene/type Range </div><div>/gate/source/ARFSource/setMinEnergy 364.5 keV</div><div> /gate/source/ARFSource/setEnergyRange 0. keV </div><div><br></div><div>Thanks all in advance. </div><div><br></div><div>Best regards. </div><div><br></div><div>Leda Lorenzon</div></body></html>