<div dir="ltr">Dear GATE users, <div><br></div><div>Has anyone experienced a similar issue with the deadtime module in the PET detector? Could you please generously share your thoughts or give any help? </div><div><br></div><div>Greatly appreciated. </div><div><br></div><div>Zhengzhi </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, May 15, 2020 at 9:05 AM Albert Grace Lieu <<a href="mailto:albertnew2018@gmail.com">albertnew2018@gmail.com</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"><div dir="ltr"><div style="color:rgb(32,33,36);font-family:Roboto,RobotoDraft,Helvetica,Arial,sans-serif;font-size:medium;min-height:100%"><div style="width:1280px"><div style="float:left;display:flex;width:1280px"><div style="min-height:1px;float:left;overflow:hidden;width:1037px"><div id="gmail-m_-6717229018559481141m_627683070478141125gmail-:3" style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;overflow-y:scroll;padding-right:0px;height:528px"><div id="gmail-m_-6717229018559481141m_627683070478141125gmail-:1" style="padding:0px;vertical-align:bottom;min-height:338px"><table cellpadding="0" style="border-spacing:0px;padding:0px;border-collapse:collapse;width:952px;display:block"><tbody></tbody></table><div style="min-height:100%"><div style="width:1280px"><div><div><div style="float:left;display:flex;width:1280px"><div style="min-height:1px;float:left;overflow:hidden;width:1037px"><div><div><div><div><div><div id="gmail-m_-6717229018559481141gmail-:3" style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;overflow-y:scroll;padding-right:0px;height:528px"><div id="gmail-m_-6717229018559481141gmail-:1" style="padding:0px;vertical-align:bottom;min-height:338px"><div><div><div><table cellpadding="0" style="border-spacing:0px;padding:0px;border-collapse:collapse;width:952px;display:block"><tbody><tr><td style="vertical-align:top;padding:0px;display:block;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><div style="margin:0px 16px 0px 0px;padding:0px"><div><div style="background-color:transparent;color:rgb(34,34,34);min-width:502px;padding:0px"><div><div style="clear:both;padding-bottom:0px;max-width:100000px;outline:none"><div style="margin-bottom:0px;border-width:0px;border-top-style:solid;border-right-style:initial;border-bottom-style:initial;border-left-style:initial;border-top-color:rgb(239,239,239);border-right-color:initial;border-left-color:initial;border-bottom-color:initial;border-radius:0px;width:936px;float:none"><div style="padding-top:0px;background-color:transparent;border-right:0px;border-bottom:0px rgba(100,121,143,0.12);border-left:0px;border-top:none;border-radius:0px;margin-bottom:0px;margin-left:0px;margin-right:0px"><div id="gmail-m_-6717229018559481141gmail-:16k"><div style="border-left:none;padding:0px;display:flex"><div style="margin:0px;padding:0px 0px 20px;width:864px"><div><div id="gmail-m_-6717229018559481141gmail-:16n" style="font-size:0.875rem;direction:ltr;margin:8px 0px 0px;padding:0px"><div id="gmail-m_-6717229018559481141gmail-:16m" style="overflow:hidden;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:small;line-height:1.5;font-family:Arial,Helvetica,sans-serif"><div dir="ltr"><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><i><font size="1">As my previous email account expired, please reply to this one if you can. Thank you very much. </font></i></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">Honored Gate experts and developers, </div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">I am experiencing some issues with deadtime in the PET detector when validating my simulated PET system in GATE against my real PET system. My PET system is similar to a typical standard ring PET system. I have built a corresponding GATE model to it as close as I can. But the count rate in the GATE model is twice higher than the physical system. I think it is due to the weird behavior of deadtime in digitizer settings. Then I did some simple validation simulations to prove that. In my real system, 11.3 mci (equivalent to 19 kBq/ml) is high enough to paralyze the system, i.e., the collected coincidence rate would increase then decrease as decays go by. However, in the GTE model, I have not observed such a trend yet. Here is a simple example: </div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><div><img src="cid:ii_ka79i47b0" alt="Screenshot from 2020-05-14 13-43-13.png" width="472" height="80"><br></div><div>When I doubled the initial dose from 19 kBq/ml (11.3 mci) to 38 kBq/ml (22.6 mci), Gate also doubled the count of singles. To me, the deadtime module is not working. Because 19 kBq/ml is high enough to paralyze the detector, when the dose is doubled, it shall output ways less than twice of the singles. </div><div><br></div><div>Another simulation I did to show GATE mode reacts to deadtime is varying the deadtime: </div><div><br></div><div><div><img src="cid:ii_ka79p9h01" alt="Screenshot from 2020-05-14 14-10-41.png" width="472" height="66"><br></div></div><div>As you can see from the results above, the counts of singles barely change when deadtime increases from 10 ns to 100000 ns, which is very weird behavior to me. Also, 19 kBq/ml (11.3 mci) shall be high enough to paralyze the system. </div><div><br></div><div>Please provide any clue or any help to correct it. Thank you very much. </div><div>Sincerely,</div><div>Zhengzhi </div><div><br></div><div><span style="font-size:12pt"><br></span></div><div><span style="font-size:12pt"><br></span></div><div><span style="font-size:12pt">Following is my digitizer settings: </span><br></div><div>#=====================================================<br># D I G I T I Z E R: DETECTOR ELECTRONIC RESPONSE<br>#=====================================================<br># A D D E R<br>/gate/digitizer/Singles/insert adder<br><br># R E A D O U T<br>/gate/digitizer/Singles/insert readout<br>#/gate/digitizer/Singles/readout/setPolicy TakeEnergyCentroid<br>#TakeEnergyWinner<br>/gate/digitizer/Singles/readout/setDepth 5<br><br># E N E R G Y B L U R R I N G<br>/gate/digitizer/Singles/insert blurring<br>/gate/digitizer/Singles/blurring/setResolution 0.15<br>/gate/digitizer/Singles/blurring/setEnergyOfReference 511. keV<br><br># E N E R G Y C U T<br>/gate/digitizer/Singles/insert thresholder<br>/gate/digitizer/Singles/thresholder/setThreshold 395. keV<br>/gate/digitizer/Singles/insert upholder<br>/gate/digitizer/Singles/upholder/setUphold 600. keV<br><br>/gate/digitizer/Singles/insert timeResolution<br>/gate/digitizer/Singles/timeResolution/setTimeResolution 0.700 ns<br><br># D E A D T I M E<br>/gate/digitizer/Singles/insert deadtime<br>/gate/digitizer/Singles/deadtime/setDeadTime 1000. ns<br>/gate/digitizer/Singles/deadtime/setMode paralysable<br>/gate/digitizer/Singles/deadtime/chooseDTVolume Crystal<br><br><br>#=====================================================<br># C O I N C I D E N C E S O R T E R<br>#=====================================================<br>/gate/digitizer/Coincidences/setWindow 5. ns<br>/gate/digitizer/Coincidences/minSectorDifference 1<br>/gate/digitizer/Coincidences/setOffset 0. ns<br>#/gate/digitizer/Coincidences/setMultiplePolicy killAll<br>/gate/digitizer/Coincidences/describe<br><br>/gate/digitizer/name delayedCoinc<br>/gate/digitizer/insert coincidenceSorter<br>/gate/digitizer/delayedCoinc/setOffset 90. ns<br>/gate/digitizer/delayedCoinc/setWindow 5. ns<br>/gate/digitizer/delayedCoinc/minSectorDifference 1<br>/gate/digitizer/delayedCoinc/describe<br><br>/gate/digitizer/name finalCoinc<br>/gate/digitizer/insert coincidenceChain<br>/gate/digitizer/finalCoinc/addInputName delayedCoinc<br>/gate/digitizer/finalCoinc/addInputName Coincidences<br>/gate/digitizer/finalCoinc/usePriority true<br>/gate/digitizer/finalCoinc/insert deadtime<br>/gate/digitizer/finalCoinc/deadtime/setDeadTime 10. ns<br>/gate/digitizer/finalCoinc/deadtime/setMode paralysable<br>/gate/digitizer/finalCoinc/describe</div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></td><td 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