<div dir="ltr"><div>Dear Zahra,</div><div><br></div><div>In general, the greater activity used in a study, the higher the ratio of Random-to-True coincidence rates. <br></div><div>This is because the random coincidence rate increases as the <b>square of the amount of activity</b> present, whereas the true coincidence rate increases only <b>linearly </b>with the amount<br>of activity administered. <br></div><div>In addition, the ratio of Random-to-True coincidence decreases in proportion to the <b>width </b>of the coincidence timing window.</div><div>Therefore, I think it is normal <br></div><div><br></div><div>Milad Fard,</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Aug 3, 2020 at 3:32 PM <<a href="mailto:gate-users-request@lists.opengatecollaboration.org">gate-users-request@lists.opengatecollaboration.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Send Gate-users mailing list submissions to<br>
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Today's Topics:<br>
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   1. Re: N E C R (Xinjie Cao)<br>
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Message: 1<br>
Date: Sun, 2 Aug 2020 10:46:49 -0400<br>
From: Xinjie Cao <<a href="mailto:xinjie.cao@stonybrook.edu" target="_blank">xinjie.cao@stonybrook.edu</a>><br>
To: Zahra Fathihossienabadi <<a href="mailto:zahrafathi71@ph.iut.ac.ir" target="_blank">zahrafathi71@ph.iut.ac.ir</a>><br>
Cc: <a href="mailto:gate-users@lists.opengatecollaboration.org" target="_blank">gate-users@lists.opengatecollaboration.org</a><br>
Subject: Re: [Gate-users] N E C R<br>
Message-ID:<br>
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<br>
Hi Zahra,<br>
<br>
I think it is normal, my NEMA test is similar. You could also find the<br>
similar situation in some PET simulation papers.<br>
<br>
Best,<br>
Xinjie<br>
<br>
On Sun, Aug 2, 2020 at 1:51 AM Zahra Fathihossienabadi <<br>
<a href="mailto:zahrafathi71@ph.iut.ac.ir" target="_blank">zahrafathi71@ph.iut.ac.ir</a>> wrote:<br>
<br>
> Hi dear users<br>
> I want to get the scatter fraction and true and random rate so that I can<br>
> calculate parameter NECR.<br>
> I putted the phantom similar to the NEMA.<br>
> for example When I want to calculated NECR for 10 kBq/ml, the true rate is<br>
> much lower than the random rate.<br>
> Is this normal or is there something wrong with my simulation?<br>
><br>
> Thanks in advance for any answers.<br>
> _______________________________________________<br>
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-- <br>
*....................................................*<br>
*Xinjie Cao*<br>
*M.E. / Ph.D. student*<br>
*Research Project Assistant*<br>
*Department of Electrical and Computer Engineering & Radiology *<br>
*Novel Medical Imaging Technologies Lab*<br>
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*Tel: +1 (631)202-9445*<br>
<a href="http://you.stonybrook.edu/goldan/people/" rel="noreferrer" target="_blank">you.stonybrook.edu/goldan/people/</a><br>
*email: **xinjie.cao@stonybroo*<a href="http://k.edu" rel="noreferrer" target="_blank">k.edu</a> <<a href="mailto:xinjie.cao@stonybrook.edu" target="_blank">xinjie.cao@stonybrook.edu</a>><br>
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