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<p class="MsoNormal"><span lang="EN-US">Hi Dmitry,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">You can read about the calculation of dose and its uncertainty
<a href="https://opengate.readthedocs.io/en/latest/voxelized_source_and_phantom.html?highlight=dose%20actor#dose-collection">
here</a>. The number of events required to reach 1% uncertainty is a bit of a loaded question. It will depend on your dose actor resolution and the location of the volume of interest so it may take some trial and error to find a suitable number. I only have
dose actor experience working with beta-emitters on the order of a few MeV for which I required 4x10^8 primaries to achieve reasonable uncertainties.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Larger volumes can have lower uncertainty due to containment of more energy-depositing events. Dose voxels near your proton beam will encounter more interactions and lower uncertainty than voxels far from the beam where
few interactions occur. Also keep in mind that your voxel size will have an effect on the dose since absorbed dose is calculated as energy deposited per unit mass.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Hope this helps,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Matthew</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:-webkit-standard;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:-webkit-standard;color:black">--</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:-webkit-standard;color:black">Matthew Strugari<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:-webkit-standard;color:black">PhD Candidate</span><span style="color:black"> at
</span><span lang="EN-US" style="font-size:10.5pt;font-family:-webkit-standard;color:black">Biomedical Translational Imaging Centre - BIOTIC,<br>
5890 University Ave, Halifax, NS, B3K 6R8</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Gate-users <gate-users-bounces@lists.opengatecollaboration.org> on behalf of Dmitry Hits <dmitry.hits@phys.ethz.ch><br>
<b>Date: </b>Tuesday, May 11, 2021 at 12:31<br>
<b>To: </b>Gate-Users <gate-users@lists.opengatecollaboration.org><br>
<b>Subject: </b>[Gate-users] Dose results interpretation<o:p></o:p></span></p>
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<p class="MsoNormal" style="line-height:12.0pt;mso-line-height-rule:exactly"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:white">CAUTION:</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:white"> The Sender
of this email is not from within Dalhousie.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:white">Hi Gaters, </span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I am trying to understand results output by the dose actor, which I enabled with the following lines:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">/gate/actor/addActor DoseActor dose5<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/save <span style="font-size:8.5pt;font-family:Menlo;color:black">results/dose_2021May11_171652_5.root</span><o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/attachTo box5<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/stepHitType random<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/setResolution 1 10 1<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/enableDose true<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/enableUncertaintyDose true<o:p></o:p></p>
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<p class="MsoNormal"> /gate/actor/dose5/enableNumberOfHits true<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The source is a pencil beam of protons of 100 MeV. I simulated 10000 events.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Here is the histogram I got:<o:p></o:p></p>
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<p class="MsoNormal"><img border="0" width="761" height="435" style="width:7.927in;height:4.5312in" id="FB1EE12D-028F-4D15-BF0D-945FF1B50B9B" src="cid:image001.png@01D74675.94466BC0"><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">My question is why is the error so large? How is it calculated?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Cheers,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dmitry<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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