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Greetings,</div>
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In short, I don't know. It could be too many thing since I am missing a great portion of your simulation configuration. As it stand, I am not even sure if the problem is in the choice of digitizer. </div>
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Most, including I, won't take the time to analyze/read a complete list of mac files. Thus, <span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">I suggest that you start from one of Gate example, which we know should work, and slowly
replace it with your simulation configuration (Or do the reverse). This way, you will be able to "find" the part, 3-4 lines, from where the problem is born.</span></div>
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<span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">Good luck in your hunt!</span></div>
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Bests,</div>
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Maxime Toussaint</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>De :</b> nicole.jurjew@gmail.com <nicole.jurjew@gmail.com><br>
<b>Envoyé :</b> 10 novembre 2020 05:47<br>
<b>À :</b> Maxime Toussaint <Maxime.Toussaint@USherbrooke.ca>; gate-users@lists.opengatecollaboration.org <gate-users@lists.opengatecollaboration.org><br>
<b>Objet :</b> AW: [Gate-users] Number of counts too low</font>
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<p class="x_MsoNormal"><span style="">Dear Maxime,</span></p>
<p class="x_MsoNormal"><span style=""> </span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">thank you for your reply!</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style=""> </span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">I tried your suggestions out: The DTVolume level changes the number of counts a little, but by far not significantly (about 0.5% more counts where I need around 50% more for low energies). I also ran with the
most simple digitizer: no energy blurring, no time resolution or dead time added. I get the same results: about 0.5 % increase of counts, but no significant changes.</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style=""> </span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">Do you maybe have any other ideas why I get too little counts?</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style=""> </span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">Thank you!</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">Kind regards,</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style="">Nicole</span></p>
<p class="x_MsoNormal"><span lang="EN-US" style=""> </span></p>
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<p class="x_MsoNormal"><b>Von:</b> Gate-users <gate-users-bounces@lists.opengatecollaboration.org>
<b>Im Auftrag von </b>Maxime Toussaint<br>
<b>Gesendet:</b> Dienstag, 10. November 2020 05:18<br>
<b>An:</b> gate-users@lists.opengatecollaboration.org<br>
<b>Betreff:</b> Re: [Gate-users] Number of counts too low</p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:12.0pt; color:black">Greetings,</span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:12.0pt; color:black">I have never used the deadtime module, but are you sure about your choice for the following?</span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:black; background:white">/gate/digitizer/Singles/deadtime/chooseDTVolume rsector</span><span style="font-size:12.0pt; color:black"></span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:black; background:white">It seems to be to "low" in "geometry level" for classical scanner configuration.</span><span style="font-size:12.0pt; color:black"></span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:black; background:white">If yes, did you try to simplify (e.g. remove dead time) of your digitizer to find the origin of the problem? </span><span style="font-size:12.0pt; color:black"></span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:12.0pt; color:black"> </span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:black; background:white">Bests,</span><span style="font-size:12.0pt; color:black"></span></p>
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<p class="x_MsoNormal" style="background:white"><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:black; background:white">Maxime Toussaint</span><span style="font-size:12.0pt; color:black"></span></p>
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<p class="x_MsoNormal"><b><span style="color:black">De :</span></b><span style="color:black"> Gate-users <<a href="mailto:gate-users-bounces@lists.opengatecollaboration.org">gate-users-bounces@lists.opengatecollaboration.org</a>> de la part de Nicole Jurjew
<<a href="mailto:nicole.jurjew@gmail.com">nicole.jurjew@gmail.com</a>><br>
<b>Envoyé :</b> 6 novembre 2020 06:32<br>
<b>À :</b> <a href="mailto:gate-users@lists.opengatecollaboration.org">gate-users@lists.opengatecollaboration.org</a> <<a href="mailto:gate-users@lists.opengatecollaboration.org">gate-users@lists.opengatecollaboration.org</a>><br>
<b>Objet :</b> [Gate-users] Number of counts too low</span> </p>
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<p class="x_MsoNormal">Dear Gate Users!<br>
<br>
I am using GATE v.8.0 to model a preclinical PET system. I carried out the NEMA - NEC measurements on the real scanner and also simulated them in GATE. The curves don't look much alike. The simulation produces significantly less counts than what is detected
with the real system.<br>
<br>
I determined the number of gamma particles entering my crystal with the "Kill Tracks" Actor. (I always ran one simulation to count the Nb of tracks killed in the crystal and one where no tracks are killed to be able to calculate the Nb of prompts generated.)<br>
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An activity of 0.58 MBq inside a polyethylene cylinder results in a total number of ~21.000 counts with the digitizer settings you can see below. Number of killed gamma particles is ~855000.<br>
Energy window, coincidence timing window and dead time are set to align with specifications given by the vendor. I tried out many different digitizer settings, but none of them leads to a result close to the measurements, also not for higher activities up
to 40 MBq.<br>
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Do you have an idea where too little counts could come from?<br>
<br>
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Thank you in advance!<br>
Nicole Jurjew<br>
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### DIGITIZER ###<br>
<br>
/gate/digitizer/Singles/insert adder<br>
/gate/digitizer/Singles/insert readout<br>
/gate/digitizer/Singles/readout/setPolicy TakeEnergyWinner<br>
/gate/digitizer/Singles/readout/setDepth 1<br>
<br>
/gate/digitizer/Singles/insert blurring<br>
/gate/digitizer/Singles/blurring/setResolution 0.1<br>
/gate/digitizer/Singles/blurring/setEnergyOfReference 511. keV<br>
<br>
/gate/digitizer/Singles/insert thresholder<br>
/gate/digitizer/Singles/thresholder/setThreshold 250.39 keV<br>
/gate/digitizer/Singles/insert upholder<br>
/gate/digitizer/Singles/upholder/setUphold 771.61 keV<br>
<br>
<br>
# C O I N C I S O R T E R <br>
/gate/digitizer/Coincidences/setWindow 7. ns<br>
/gate/digitizer/Coincidences/MultiplesPolicy takeWinnerOfGoods<br>
<br>
/gate/digitizer/name delay<br>
/gate/digitizer/insert coincidenceSorter<br>
/gate/digitizer/delay/setWindow 7. ns<br>
/gate/digitizer/delay/setOffset 20 ns<br>
<br>
<br>
# TIME RESOLUTION<br>
/gate/digitizer/Singles/insert timeResolution<br>
/gate/digitizer/Singles/timeResolution/setTimeResolution 0.5 ns <br>
<br>
<br>
# DEAD TIME<br>
/gate/digitizer/Singles/insert deadtime<br>
/gate/digitizer/Singles/deadtime/setDeadTime 850. ns<br>
/gate/digitizer/Singles/deadtime/setMode nonparalysable<br>
/gate/digitizer/Singles/deadtime/chooseDTVolume rsector</p>
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