<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi,</div><div><br></div><div>You can change the geometry. If changed correctly, most, if not all, the iterative cone beam reconstruction will work. </div><div><br></div><div>Best regards,</div><div>Louie<br><br>Greetings from my iOS!</div><div><br>On 26 Feb 2015, at 21:19, Robert Calließ <<a href="mailto:robert.calliess@gmx.de">robert.calliess@gmx.de</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hello Vahid,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think you need to add a new reconstruction filter for it. For the first projection the object usually is placed so that the<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">resulting projection image covers the upper half of the detector. And you will need some additional handling (z-increment).<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I guess you could do a little work around with the current rtk. If you only reconstruct an rectangular roi around<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">the detector’s center where the perspective distortion (because of the cone) is minimal. And then you add these<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">seperate volumes to a final volume. This is just an idea. I do not know how the result will look like. Think of it like a TDI<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">but with a wider sensor array.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I do not know the code in detail, but if it were possible to have seperate geometry settings for every projection image it <o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">would be possible to model the helical trajectory by the changing geometry without changing /adding code.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">But let’s see what grandmasters of RTK will suggest.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best regards,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Robert<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> <o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Von:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Rtk-users [<a href="mailto:rtk-users-bounces@public.kitware.com">mailto:rtk-users-bounces@public.kitware.com</a>] <b>Im Auftrag von </b>vahid ettehadi via Rtk-users<br><b>Gesendet:</b> Donnerstag, 26. Februar 2015 20:35<br><b>An:</b> <a href="mailto:rtk-users@public.kitware.com">rtk-users@public.kitware.com</a><br><b>Betreff:</b> [Rtk-users] Helical cone-beam reconstruction with RTK<o:p></o:p></span></p></div></div><p class="MsoNormal"><o:p> </o:p></p><div><div id="yui_3_16_0_1_1424979162755_6732"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">Dear RTK users,<o:p></o:p></span></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1424979162755_6721"><div id="yui_3_16_0_1_1424979162755_6720"><div id="yui_3_16_0_1_1424979162755_6719"><div id="yui_3_16_0_1_1424979162755_6725"><div id="yiv6859553979"><div id="yui_3_16_0_1_1424979162755_6724"><div id="yui_3_16_0_1_1424979162755_6723"><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">I am using the RTK code to reconstruct the image for a bench-top micro-CT in a circular cone-beam geometry. It works well with FDK algo. Thanks RTK.<o:p></o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">I would like to change the current source trajectory from circular to helical. I was wondering is it possible to use the RTK for helical reconstruction only with some simple modification?<o:p></o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">I don't know well about reconstruction process and I don't know which type of modification is necessary to use RTK for a helical cone beam geometry. So, any suggestion and recommendation would be appreciated.<o:p></o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">Sincerely,<o:p></o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black">Vahid<o:p></o:p></span></p></div><div id="yiv6859553979yui_3_16_0_1_1424895780864_6655"><p class="MsoNormal" style="background:white"><span style="font-size:10.5pt;font-family:"Helvetica","sans-serif";color:black"> <o:p></o:p></span></p></div></div></div></div><p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p></div></div></div></div></div></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>Rtk-users mailing list</span><br><span><a href="mailto:Rtk-users@public.kitware.com">Rtk-users@public.kitware.com</a></span><br><span><a href="http://public.kitware.com/mailman/listinfo/rtk-users">http://public.kitware.com/mailman/listinfo/rtk-users</a></span><br></div></blockquote></body></html>