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</o:shapelayout></xml><![endif]--></head><body lang=DE link=blue vlink=purple><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 [mailto:rtk-users-bounces@public.kitware.com] <b>Im Auftrag von </b>vahid ettehadi via Rtk-users<br><b>Gesendet:</b> Donnerstag, 26. Februar 2015 20:35<br><b>An:</b> rtk-users@public.kitware.com<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></body></html>