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Dear GATE users,
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<div class="">I have been simulating PET acquisitions using GATE on an XCAT phantom for reconstruction using STIR. The reconstruction processes is iterative and therefore I have need to estimate the contributions due to Random and Scattered events in the measured
data. I am estimating the Randoms from the Delayed coincidence data output by GATE using a 200ns Delayed offset. Both the Coincidence and Delayed windows are set to 4.9ns. </div>
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<div class="">Please see my digitiser on GitHub: <font color="#419cff" class=""><span style="caret-color: rgb(65, 156, 255);" class=""><u class=""><a href="https://github.com/UCL/STIR-GATE-Connection/blob/master/ExampleScanners/D690/digitiser_D690https://github.com/UCL/STIR-GATE-Connection/blob/master/ExampleScanners/D690/digitiser_D690.mac#L39-L54" class="">https://github.com/UCL/STIR-GATE-Connection/blob/master/ExampleScanners/D690/digitiser_D690https://github.com/UCL/STIR-GATE-Connection/blob/master/ExampleScanners/D690/digitiser_D690.mac#L39-L54</a></u></span></font></div>
<div class=""><u style="caret-color: rgb(19, 133, 255); color: rgb(19, 133, 255);" class="">.mac#L39-L54</u></div>
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<div class="">The problem is as follows. I unlist (using STIR) all valid events in the Delayed ROOT file. I unlist all random events (defined as the photons having different eventIDs) from the Coincidence ROOT file. The result is, ~10% more events in the Delayed
data, which has knock on effects to my Randoms estimation and into the Scatter estimation…</div>
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<div class="">Does anyone have any idea why I might have more events in my Delayed data than Random events in my Coincidence data?</div>
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<div class="">Regards,</div>
<div class="">Robert Twyman</div>
<div class="">Ph.D Student</div>
<div class="">UCL</div>
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