<html><head></head><body><div class="ydp7f99dc27yahoo-style-wrap" style="font-family:courier new, courier, monaco, monospace, sans-serif;font-size:13px;"><div><div dir="ltr" data-setdir="false">Hello Cassandra,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">You can also check this article (<a href="https://www.nature.com/articles/s41598-019-56258-5.pdf?proof=t" rel="nofollow" target="_blank">https://www.nature.com/articles/s41598-019-56258-5.pdf?proof=t</a>) to understand exactly what is different in the calculation of LET using the 'Dose Average' method.</div><div dir="ltr" data-setdir="false">e.g.: "<span>The LET from each particle is weighted with respect to its contribution to the local dose in each voxel"</span></div><div dir="ltr" data-setdir="false"><span><br></span></div><div dir="ltr" data-setdir="false"><span>Kind regards,</span></div><div dir="ltr" data-setdir="false"><span>Konstantinos</span></div><div><br></div><div class="ydp7f99dc27signature"><div style="font-family:courier, monaco, monospace, sans-serif;font-size:13px;"><div style="color:rgb(0, 0, 0);font-family:Arial;font-size:16px;font-style:normal;font-weight:normal;letter-spacing:normal;orphans:2;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;"><span style="font-style:italic;">-----------------------------------------------------</span></div><span style="color:rgb(0, 0, 0);font-family:Arial;font-size:16px;font-weight:normal;letter-spacing:normal;orphans:2;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;font-style:italic;"> Konstantinos Chatzipapas<br> Medical Physicist, </span><span style="color:rgb(0, 0, 0);font-family:Arial;font-size:16px;font-weight:normal;letter-spacing:normal;orphans:2;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;font-style:italic;">MSc<br></span><div style="color:rgb(0, 0, 0);font-family:Arial;font-size:16px;font-style:normal;font-weight:normal;letter-spacing:normal;orphans:2;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;"><div><span style="font-style:italic;"> <span style="font-weight:bold;">University of Patras</span></span></div><div><span style="font-style:italic;"><span style="font-weight:bold;"><br></span></span></div><div dir="ltr"><span style="font-style:italic;"><span style="font-weight:bold;"> web: <a href="http://physicsfeed.blogspot.com/" rel="nofollow" target="_blank">Physics Magazine</a></span></span></div></div></div></div></div>
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Στις Τρίτη, 16 Μαρτίου 2021, 10:24:36 π.μ. EET, ο χρήστης Andreas Resch <resch.andi@gmail.com> έγραψε:
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<div><div id="yiv7213434296"><div><div dir="ltr">Hi Cassandra,<div><br clear="none"></div><div>LETt,d is an averaged value, so summing it along one dimension if you score a 3D map is not the same as scoring a 1D map. So the two curves should not look the same. </div><div><br clear="none"></div><div>There is the option "doParallelCalculation" giving you the numerator and denominator separately. If you sum those up individually and afterwards do the division you should end up in the same result as the 1D output. See also here:</div><div><a rel="nofollow noopener noreferrer" shape="rect" target="_blank" href="https://opengate.readthedocs.io/en/latest/tools_to_interact_with_the_simulation_actors.html#let-actor">https://opengate.readthedocs.io/en/latest/tools_to_interact_with_the_simulation_actors.html#let-actor</a><br clear="none"></div><div>note that the denominator is actually the dose distribution in your case.</div><div><br clear="none"></div><div>cheers,</div><div>Andreas</div></div><br clear="none"><div class="yiv7213434296gmail_quote"><div class="yiv7213434296yqt4074064027" id="yiv7213434296yqtfd85241"><div class="yiv7213434296gmail_attr" dir="ltr">Am Mo., 15. März 2021 um 20:45 Uhr schrieb Cassandra Miller <<a rel="nofollow noopener noreferrer" shape="rect" ymailto="mailto:cassandramiller@phas.ubc.ca" target="_blank" href="mailto:cassandramiller@phas.ubc.ca">cassandramiller@phas.ubc.ca</a>>:<br clear="none"></div><blockquote class="yiv7213434296gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex;">Hi everyone,<br clear="none">
<br clear="none">
I'm trying to do some calculations using the LET actor but my results <br clear="none">
don't match when I think they should.<br clear="none">
<br clear="none">
I created a water density box (1x3x1 mm) with a point source of 500 keV <br clear="none">
beta particles at the top of the box in the y-direction. I used the LET <br clear="none">
actor as both a 3D matrix and an effectively 1D matrix, essentially like so:<br clear="none">
<br clear="none">
/gate/actor/addActor LETActor MyActor3D<br clear="none">
/gate/actor/MyActor3D/save output/myLETactor3D.mhd<br clear="none">
/gate/actor/MyActor3D/attachTo box<br clear="none">
/gate/actor/MyActor3D/setResolution 25 75 25<br clear="none">
/gate/actor/MyActor3D/setType DoseAveraged<br clear="none">
<br clear="none">
/gate/actor/addActor LETActor MyActor1D<br clear="none">
/gate/actor/MyActor1D/save output/myLETactor.mhd<br clear="none">
/gate/actor/MyActor1D/attachTo box<br clear="none">
/gate/actor/MyActor1D/setResolution 1 75 1<br clear="none">
/gate/actor/MyActor1D/setType DoseAveraged<br clear="none">
<br clear="none">
I would expect the output to look similar, and the 3D matrix to exactly <br clear="none">
match the 1D matrix when I sum it in the x and z direction, to change <br clear="none">
its shape to (1, 75, 1) so they are the exact same shape.<br clear="none">
<br clear="none">
I get the attached images which don't look the same at all. They're not <br clear="none">
even the same shape. Does anyone know why this is? Does changing the <br clear="none">
resolution change something else I'm not aware of? I also tried using <br clear="none">
the command "/gate/actor/MyActor1D/setVoxelSize 1 0.04 1 mm" to <br clear="none">
make sure my 1D actor was capturing the entire box, but the shape still <br clear="none">
didn't match.<br clear="none">
<br clear="none">
Best,<br clear="none">
Cassandra<br clear="none">
<br clear="none">
-- <br clear="none">
<br clear="none">
Cassandra Miller<br clear="none">
PhD Candidate, Physics<br clear="none">
Quantitative Radiomolecular Imaging and Therapy Lab<br clear="none">
Department of Physics and Astronomy, University of British Columbia<br clear="none">
<br clear="none">
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