<FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><FONT face="Default Sans Serif, Verdana, Arial, Helvetica, sans-serif" size=2><DIV><DIV><FONT face="Courier New">Hello everybody,</FONT></DIV><FONT face="Courier New"><DIV> <BR></FONT><FONT face="Courier New"> My name is Martin Janecek and I am part of a the Imaging Physics Group at Washington University in St Louis. We are developing an unconventional PET system consisting of a small detector ring - an insert - placed inside of a large clinical scanner ring. The insert has smaller (high-resolution) LSO detectors compared to the scanner detectors. We want to simulate the system in GATE. A problem arises however when we want to attach the detectors to a system. Does the GATE code allow to attach two different resolution detectors in coincidence? (We get an error message, telling us a volume is already attached when trying to attach a second layer). The "attachment tree" seems to be of a single branch, without the possibility to attach two different detector blocks to one layer (Table 4.2 in the manual). </FONT></DIV><DIV><FONT face="Courier New"></FONT> </DIV><DIV><FONT face="Courier New"></FONT></DIV><DIV><FONT face="Courier New"></FONT></DIV><FONT face="Courier New"></FONT></DIV><DIV></DIV><DIV><FONT face="Courier New">Sincerely,</FONT></DIV><DIV> </DIV><DIV><FONT face="Courier New"></FONT></DIV><DIV></DIV><DIV><FONT face="Courier New"></FONT></DIV><DIV><FONT face="Courier New">WashU Imaging Physics Group through Martin Janecek</FONT></DIV></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT></FONT>