<div dir="ltr">Hi Maxime, <div><br></div><div>I did a simple simulation to verify whether a back-to-back gamma generator creates colinear or accolinear gamma pairs. I used a point source with a single emission direction to generate back to back gammas in a cylindrical PET system (in GATE 8.2). Then I collected hits file and coincidences file. I used valid coincidence event IDs to find its first hit position registered by the PET system (ideal resolution). Please note that I did not use any following commands:</div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px;margin:0px"> /gate/source/NAME/setAccolinearityFlag true</span></div><div><span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px;margin:0px"> /gate/source/NAME/setAccoValue 0.5 deg</span> </div></blockquote><div><br></div><div>Here is what I found: </div><div>It looks back-to-back gamma source has accolinearity enabled by default. The mean is 5.5 degrees with and a standard deviation of 4.2. </div><div><img src="cid:ii_kgr3cebl0" alt="Screenshot from 2020-10-26 14-58-32.png" width="523" height="404"><br></div><div><br></div><div>My question is whether back-to-back gamma source has accolinearity enabled by default? Maybe I shall have looked into GateBackToBack.cc, however, source code might have compiled with other flags which I don't know of. </div><div><br></div><div>Thanks for your precious time answering. </div><div><br></div><div>Zhengzhi</div><div> <br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Oct 26, 2020 at 10:59 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">Hi Maxime, <div><br></div><div>Thanks for sharing your findings regarding this accolineraity feature associated with the back-to-back gamma source. I did not see "setAccolinearityFlag" command in the GATE 8 and 9 manual either and am skeptical about its validity. May I know your conclusion on the usage of
accolineraity feature in GATE? Is it still supported or dead? How can one still possibly use it correctly?</div><div><br></div><div>Thanks a lot. </div><div><br></div><div>Sincere wishes,</div><div><br></div><div>Zhengzhi </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Jul 1, 2020 at 11:39 AM Maxime Toussaint <<a href="mailto:Maxime.Toussaint@usherbrooke.ca" target="_blank">Maxime.Toussaint@usherbrooke.ca</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">
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<div style="background-color:white;margin:0px">Greetings,<br>
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<div style="background-color:white;margin:0px">If one look<span><span>s</span></span> into the mailing list or in the Gate code, one can find that there is an option to simulate accolinearity from back to back source. The commands to use are as follow:</div>
<div style="background-color:white;margin:0px"><span style="margin:0px"> /gate/source/NAME/setAccolinearityFlag true<br>
</span><span style="margin:0px"> /gate/source/NAME/setAccoValue 0.5 deg</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px"><br>
</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px">In short, is this feature validated and still supported?<br>
</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px"><br>
</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px">In the following, I detail what I found from my search on that feature.</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px"><br>
</span></div>
<div style="background-color:white;margin:0px"><span style="margin:0px">This feature is not mentioned in the current openGate wiki (or at least, it was not found with the wiki search tool). I did a quick "cntrl+f" search of "setAccolinearityFlag" for the
userguides available from v6.0 to the last available and I did not found a single mention</span> of that keyword. However, if we look at the mailing list, we can find the following:</div>
<div style="background-color:white;margin:0px">
<ul>
<li>A possible bug was found in 2011 for which the resulting thread does not provide a clear conclusion about if the bug was corrected or if it was a real bug [1].<br>
</li><li>Around two years later, the feature was proposed to a user [4].</li><li>This feature seems to be still used currently [2, 3]. In [3], the user asked for some tips on the feature which were not answered.<br>
</li><li>From Gate v5.0 to v6.0, a bug was found and corrected [5, 6, 7].<br>
</li></ul>
</div>
<div style="background-color:white;margin:0px">I did try to look into the available release note of Gate and the Gate github but I did not find a mention about that feature.<br>
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<div style="background-color:white;margin:0px"><br>
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<div style="background-color:white;margin:0px">Currently, the option to test Gate with accolinearity validation does not work out-of-the-box with that feature. When I tried to activate the accollinearity error graph creation, the resulting graph indicated
pure back-to-back events. I have built some tests by hand[*] and it showed that a Gaussian angular error was indeed simulated which is good. However, when I compared the accolinearity error resulting from that feature to when using a positron source[**], the
profile were clearly different. The latter being Gaussian-like, as expected. It would seems that something unexpected happens when the angular error is applied to the gamma pairs momentum with that feature. While I did try to make sense of the code in the
method "GenerateVertex" of GateBacktoBack.cc, I must admit I fail to comprehend all the steps it does.<br>
</div>
<div style="background-color:white;margin:0px"><br>
</div>
<div style="background-color:white;margin:0px">Thus, it seems that this feature might have some problems or that it is not completely supported. If it is indeed the case, I will propose a modification to the wiki such that it mention the existence of that
feature but warns the users that it might not work as intended. If it should work, I will try to make a MWE of my tests and ask for validation.<br>
</div>
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<div style="background-color:white;margin:0px">Best,<br>
Maxime Toussaint</div>
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<div style="background-color:white;margin:0px">[1]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2011-February%2F004842.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959885713&sdata=hErgjKVo%2BGaOLEjOHvH8hG1YyI5lN5dqKYuGGQwOx7A%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2011-February/004842.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2011-February/004842.html</a></div>
<div style="background-color:white;margin:0px">[2]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2020-June%2F011680.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959895705&sdata=2r8SoyW0IZrf%2Btztjjbk9BW55g2tRu1cEOv56fwnhW4%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2020-June/011680.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2020-June/011680.html</a><br>
[3]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2019-December%2F011222.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959895705&sdata=H%2BAvIhdArNubUAJJXV9l4Wzq18IozEXcLOu8jP%2FZweA%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2019-December/011222.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2019-December/011222.html</a></div>
<div style="background-color:white;margin:0px">[4]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2012-November%2F006068.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959905700&sdata=%2B1j5zAFPGqBNayNUn1I6uf7joGaLYCdPOT5vbnRbuO0%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2012-November/006068.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2012-November/006068.html</a></div>
<div style="background-color:white;margin:0px">[5]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2010-November%2F004684.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959905700&sdata=DAVufxRn3d%2BCb7VxOULE9siiR9FQ6pWBzo2nb%2FrYA3k%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2010-November/004684.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2010-November/004684.html</a><br>
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<div style="background-color:white;margin:0px">[6]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2010-November%2F004683.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959915693&sdata=wTA7OwcDUmICDa%2FOLyAgP%2FiRPIWTO%2FwIWt27j1GKcIY%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2010-November/004683.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2010-November/004683.html</a><br>
</div>
<div style="background-color:white;margin:0px">[7]<span> </span><a href="https://can01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.opengatecollaboration.org%2Fpipermail%2Fgate-users%2F2010-October%2F004599.html&data=02%7C01%7CMaxime.Toussaint%40USherbrooke.ca%7C25315ca43ca74ed7ad0608d81de0a462%7C3a5a8744593545f99423b32c3a5de082%7C0%7C0%7C637292197959915693&sdata=F%2Fwogp5s9hJC1WtE2CujQWvG3GW%2BapOOIGMIJGiQnh8%3D&reserved=0" rel="noopener noreferrer" title="URL d'origine : http://lists.opengatecollaboration.org/pipermail/gate-users/2010-October/004599.html. Cliquez ou appuyez si vous faites confiance à ce lien." style="margin:0px" target="_blank">http://lists.opengatecollaboration.org/pipermail/gate-users/2010-October/004599.html</a></div>
<div style="background-color:white;margin:0px"><br>
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<div style="background-color:white;margin:0px">[*] Outputting the "dev" variable from the file GateBacktoBack.cc</div>
<div style="background-color:white;margin:0px">[**] Outputting the momentum from the file GateBacktoBack.cc and GatePositronAnnihilation.cc, and extracting the photon pairs accolinearity.</div>
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