<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"> <HTML> <HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META NAME="Generator" CONTENT="MS Exchange Server version 6.5.7651.59"> <TITLE>RE: [Gate-users] question about the coincidence window</TITLE> </HEAD> <BODY>  Then it is an assue about GATE implementation not consistent with standard definition in any of paralyzable or nonparalyzable model? If it is true, I am fortunate to use my own code to avoid this inconsistence. Thanks, Yu Chen, Ph.D. University of Massachusetts Medical School Division of Nuclear Medicine 55 Lake Avenue North Worcester, MA 01655-0243 Phone:  (508) 856-6123 Fax:    (508) 856-4572 -----Original Message----- From: Fernando Rannou [<A HREF="mailto:rannou@diinf.usach.cl">mailto:rannou@diinf.usach.cl</A>] Sent: Thu 4/26/2007 12:28 PM To: Chen, Yu Cc: yuxuan.zhang@di.mdacc.tmc.edu; gate-users@lists.healthgrid.org Subject: RE: [Gate-users] question about the coincidence window This issue was discussed 3 years ago. I asked a very similar question when I wanted to compare random rates using two approaches. If an event arrives at time t, then a coincidence will be counted for en event in [t-tau] or [t+tau] but not [t+2tau] or [t-2tau] Fernando Rannou On Thu, 2007-04-26 at 12:14 -0400, Chen, Yu wrote: > Hi, Yuxuan, > > nice question. > I have not any experience on coincidence package in GATE since > I use our standalone coincidence program from GATE singles output, and > we can have complete control such as choosing of paralyzable or > nonparalyzable > model. > > In my opinion, coincidence window is an very important parameter in > any > coincidence experiment. It must be allowed to easily changed by users > either > for GATE or for any specific PET scanner. > > I do not completely understand what you said here for single pulse > width. > > Do you talk about width of two singles or coincidence output signal? > > If about width of single photon pulse, I do not think this width > should be > directly associated with coincidence window. As I know, GATE only > gives a time stamp > to any particular singles since no electronics response is simulated > in GATE. > > If about width of coincidence signal, why are you bothered with it? > What you need is > a count which is only dependent on coincidence window and model in > GATE, and of course > in real scanner also dependent on the width of two single pulses. As > long as you set > your coincidence window greater than twice of single pulse width, > coincidence count would > be no longer dependent on single pulse width.  > > For GATE application, what you need to do is to use the same > parameters from your real scanner, > e.g., 10 ns coincidence window, paralyzable model to get the same > results. > > Hope it helps. > > Yu Chen, Ph.D. > University of Massachusetts Medical School > Division of Nuclear Medicine > 55 Lake Avenue North > Worcester, MA 01655-0243 > Phone:  (508) 856-6123 > Fax:    (508) 856-4572 > > > > -----Original Message----- > From: gate-users-bounces@lists.healthgrid.org on behalf of > yuxuan.zhang@di.mdacc.tmc.edu > Sent: Wed 4/25/2007 6:35 PM > To: gate-users@lists.healthgrid.org > Subject: [Gate-users] question about the coincidence window > > hi All, > > I have a question about the definition of the coincidence time window, > which might be > different among the GATE society and the nuclear electronics people. > > According to the GATE user's manual, the coincidence window is the > width > of the single pulse, > however, according to some literature and electronics engineering > people, > the coincidence windows > are defined as twice of the width of the single pulse. So if they say > one > PET camera has a > coincidence window of 10 ns, this should mean that the width of the > single > pulse is 5 ns. > If this is the case, then we should setup the coincidence window in > GATE > simulation as 5 ns > rather than 10 ns. > > I've checked several published papers about the validation of the > GATE, no > one has made any comment > on this issue explicitly. So I brought this to you attention and hope > you > can give some comments. > > Best regards, > > Yuxuan > > > > > > -- > Este mensaje ha sido analizado por MailScanner > en busca de virus y otros contenidos peligrosos, > y se considera que está limpio. > MailScanner agradece a transtec Computers por su apoyo. > _______________________________________________ > Gate-users mailing list > Gate-users@lists.healthgrid.org > <A HREF="http://lists.healthgrid.org/mailman/listinfo/gate-users">http://lists.healthgrid.org/mailman/listinfo/gate-users</A> -- Este mensaje ha sido analizado por MailScanner en busca de virus y otros contenidos peligrosos, y se considera que est limpio. MailScanner agradece a transtec Computers por su apoyo. </BODY> </HTML>