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<p class="MsoNormal"><span style="color:#1F497D">Thank you very much Claude. It is very helpful.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Since Gate allow you to specify the number of radial bins to be less than N_cryst in the sinogram, how is the sinogram formed in such case? By keeping the center part of the full sinogram?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Yi <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> COMTAT Claude [mailto:claude.comtat@cea.fr]
<br>
<b>Sent:</b> Tuesday, January 08, 2008 1:40 AM<br>
<b>To:</b> Su, Yi<br>
<b>Subject:</b> RE: [Gate-users] Question about sinograms<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">Actually, they are N_cryst angles of view, and N_cryst/2 radials bin per angle of view (that is, N_crystal²/2 LORs). BUT, the location of the sinogram radial bins
for the even angle views is shifted by half the bin size relative to the odd angle views (just do the drawing of your detector ring, and you will see it).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">Let’s assume you have 12 crystals. The sinogram sampling for the 12²/2=72 LORs will look like:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">View<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">0 x x x x x x
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">1 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">2 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">3 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">4 x x x x x x
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">5 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">6 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">7 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">8 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">9 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">10 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">11 x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"> Radial bin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">In order to get a regular rectangular sinogram sampling for the 72 LORs, usually two consecutive sinogram rows are merged together:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">View<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">0 x x x x x x x x x x x x <o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">1 x x x x x x x x x x x x <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">2 x x x x x x x x x x x x <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">3 x x x x x x x x x x x x <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">4 x x x x x x x x x x x x <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">5 x x x x x x x x x x x x<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"> Radial bin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">Resulting in a N_cryst/2 view angles and N_cryst radial bins sinogram. This is exactly what is done in Gate.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">Hope this help,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";
color:navy">Claude<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">De :</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> gate-users-bounces@lists.healthgrid.org [mailto:gate-users-bounces@lists.healthgrid.org]
<b>De la part de</b> Su, Yi<br>
<b>Envoyé :</b> lundi 7 janvier 2008 23:34<br>
<b>À :</b> 'gate-users@lists.healthgrid.org'<br>
<b>Objet :</b> [Gate-users] Question about sinograms</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif""><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am a little bit confused about the terminology used in User’s Guide describing the sinogram output. For 2D sinograms, there are a maximum of N_cryst radial bins and N_cryst/2 azimuthal bins. I assume this means there are N_cryst/2 angle
of views, and in each view there are a maximum of N_cryst bins. Am I right? How are the bins generated if radial bins are specified to be smaller than N_cryst? Any information would be appreciated. Thanks a lot.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Yi <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
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