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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Hi all,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">I am in need of assistance with implementing the noise module in my digitizer for SPECT applications. I have attempted to implement this in the past with no success, but I have decided to give
it another go. The lines below are implemented in my digitizer. Please inform me if you see any apparent issues because I cannot determine why I do not have any noise in my acquisitions.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/name energy_distrib<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/insert File<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/energy_distrib/setUnitX keV<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/energy_distrib/setColumnX 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/energy_distrib/setColumnY 1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/energy_distrib/setFileName NoiseSpectrum.txt # energy in first column, counts in second column<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/energy_distrib/read<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/name dt_distrib<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/insert Exponential<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/distributions/dt_distrib/setLambda 25.13 ms<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/digitizer/Singles/insert noise<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/digitizer/Singles/noise/setDeltaTDistribution dt_distrib<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">/gate/digitizer/Singles/noise/setEnergyDistribution energy_distrib<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">An experimental 10 minute acquisition without a radioactive source produced the energy distribution below, which I have written to NoiseSpectrum.txt for import with energy_distrib. Importing the
noise spectrum appears to be successful since I can getRandom values which appear to follow the distribution and provide units of keV. One question I have here is: do I need to specify units for column Y?
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><img width="280" height="189" style="width:2.9166in;height:1.9687in" id="Picture_x0020_1" src="cid:image001.png@01D75640.FFDA6F00" alt="Chart, histogram
Description automatically generated"></span><span lang="EN-US" style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">To configure my deltaT distribution, I calculated the time difference between subsequent background noise events and filled a histogram to verify the exponential relation. Is it correct to define
lambda as the mean time difference (deltaT) between subsequent noise events, i.e. 0.025 s as indicated by the vertical line in the plot below? Configuration of the DeltaT distribution appears to be successful since I can also getRandom values which appear
follow the distribution and provide units of ms.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><img width="279" height="186" style="width:2.9062in;height:1.9375in" id="Picture_x0020_2" src="cid:image002.png@01D75640.FFDA6F00" alt="Chart, histogram
Description automatically generated"></span><span lang="EN-US" style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">To test the implemented noise module, a 10 minute simulation with a 0 MBq source does not produce any counts in the ROOT output, and a simulation with a negligible activity does not produce any
counts with event_ID == -2. How can I implement noise in my projection data? Is there something that I am missing, or perhaps a bug? Could someone also please clarify the functionality of the noise module? How are noise events actually inserted into the ROOT
output? It does not seem to be based on the start and stop times of a simulation but rather the events produced by source particles.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Matthew<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:-webkit-standard;color:black"> </span><span style="font-size:11.0pt;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="font-size:11.0pt;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="font-size:11.0pt;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><span lang="EN-US"><o:p></o:p></span></p>
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