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<p class="MsoNormal"><span lang="EN-US">Hi everyone,<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">Please disregard my previous questions. I made a mistake and failed to remove the listed energies for technetium when I copied my energy spectrum file for iodine. : )<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">On a related note, could anyone share how to obtain only the primary unscattered radiation generated directly within the source distribution from the root output? The mask I applied for each source j was (sourceID ==
j and comptonPhantom == 0 and comptonCrystal == 0) but there still appears to be counts below the photopeak.<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">Positively,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Matthew<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"><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 Matthew Strugari <matthew.strugari@dal.ca><br>
<b>Date: </b>Saturday, February 6, 2021 at 14:47<br>
<b>To: </b>gate-users@lists.opengatecollaboration.org <gate-users@lists.opengatecollaboration.org><br>
<b>Subject: </b>[Gate-users] Multi-isotope energy blurring<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Hi all,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I hope you are all having a relaxing weekend.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Does anyone have any experience with multi-isotope SPECT acquisitions with GATE? I seem to be having difficulties configuring the energy resolution properly in the digitizer. I have specified the
energy resolution according to the inverse square law using the commands:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">/gate/digitizer/Singles/insert blurring<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">/gate/digitizer/Singles/blurring/setLaw inverseSquare<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">/gate/digitizer/Singles/blurring/inverseSquare/setResolution 0.15<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">/gate/digitizer/Singles/blurring/inverseSquare/setEnergyOfReference 140.5 keV<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">In a simple test using two capillary tubes of Tc-99m/I-123, I would expect the energy resolution for I-123 to be around 14.1% centered at 159 keV according to the inverse square law. However, when
I separate the multi-isotope data according to their respective sources, I am finding that the energy resolution for I-123 is much larger than the expected 14.1% and the peak appears to be pushed towards 140 keV which causes excessive counts to be excluded
from the energy window (see attached energy spectra). I can confirm that the counts are still associated with I-123 since reconstruction of the primary window counts reveals only one line source in the dataset.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I have also tried specifying independent resolutions for each energy of reference, but this causes the photopeaks to become blurred multiple times. My next attempt would be replacing the inverse
square law with the linear law but I am not convinced that this will introduce the expected functionality.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">How can I specify the energy resolution so that blurring is automatically and correctly applied to each photopeak in the acquisition? Is this an issue with GATE due to undefined functionality for
multiple photopeaks?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Regards,<o:p></o:p></span></p>
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<p style="background:white"><span style="font-size:12.0pt;color:black">Matthew<o:p></o:p></span></p>
<p class="xmsonormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
<p class="xmsonormal" style="background:white"><span style="font-size:10.5pt;color:black">--</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
<p class="xmsonormal" style="background:white"><span style="font-size:10.5pt;color:black">Matthew Strugari</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span lang="EN-US" style="font-size:10.5pt;color:black">Biomedical Translational Imaging Centre -
<span class="markcp47xw9my"><span style="background:white">BIOTIC</span></span>,<br>
5890 University Ave, <br>
Halifax, NS, B3K 6R8</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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