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Greetings,</div>
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That is a tricky question. Sadly, I do not know if such a convenient procedure is available within Gate. While I do not have much experience in modeling an accurate acquisition system, I can offer a couple of ideas which might be useful or not.</div>
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In my humble belief, the trickiest part of your task is to define the digitizer [1] and I think it might also be where the discrepancy appear. If you want a realistic model, you should have a pretty complex digitizer that exploit most of the available module.
For example, having underestimated the Dead Time could explains what you see. It could also be due to a mismatch in the depth designation of the digitizer module: setting the DeadTime on crystal level allow more events then allowing it on module level. Thus,
the only advice I can give you is to make sure that your digitizer configuration correspond to the scanner by validating each module if possible. If any of the digitizer module do not have what you need, maybe some more advanced Gate Users could provide a
solution! </div>
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Have a nice day and good luck,</div>
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Maxime Toussaint</div>
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[1] <a href="https://opengate.readthedocs.io/en/latest/digitizer_and_detector_modeling.html?highlight=pileup#digitizer-modules" style="">https://opengate.readthedocs.io/en/latest/digitizer_and_detector_modeling.html?highlight=pileup#digitizer-modules</a><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>De :</b> Gate-users <gate-users-bounces@lists.opengatecollaboration.org> de la part de Albert Grace Lieu <albertnew2018@gmail.com><br>
<b>Envoyé :</b> 29 mai 2020 13:32<br>
<b>À :</b> gate-users <gate-users@lists.opengatecollaboration.org><br>
<b>Cc :</b> Peter Olcott <polcott@reflexion.com><br>
<b>Objet :</b> [Gate-users] Divergence between GATE simulation and the reality</font>
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<div dir="ltr">Dear GATE users,
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<div>I have modeled a real PET system in GATE as close to the real system as I can. However, during the noise equivalent count collaboration, GATE is always much better (about 50%) than the real system. After lots of effort, we looked at the results of the
NEMA sensitivity experiment (very low dose, ~500 uci) and found that GATE collected about 25% more counts than the real system. </div>
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<div>I was wondering if there is some calibration work done between GATE simulation and reality. Could someone give any help on how to further debug or make clear what causes this discrepancy between simulation and reality? </div>
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<div>Thanks a lot. </div>
<div>Zhengzhi</div>
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