<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:14px"><div dir="ltr" id="yui_3_16_0_1_1425063595136_10476"><span id="yui_3_16_0_1_1425063595136_36310">Hello,</span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span id="yui_3_16_0_1_1425063595136_10475">Thank you Robert, Louie and Simon, for your tips and recommendations. I will work on it and I will share the result or potential problems. I found the RTK more accurate and easy to use in compare with other open-source reconstruction tools such as Oscar and NiftyRec. </span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span><br></span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span id="yui_3_16_0_1_1425063595136_35024">Thank you RTK team!</span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span>Vahid</span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span><br></span></div><div dir="ltr" id="yui_3_16_0_1_1425063595136_10473"><span><br></span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 14px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Friday, February 27, 2015 4:42 AM, Simon Rit <simon.rit@creatis.insa-lyon.fr> wrote:<br> </font> </div> <br><br> <div class="y_msg_container"><div id="yiv2579130402"><div><div dir="ltr"><div><div><div><div><div><div>Hi,<br clear="none"></div>We haven't worked on helical (CB)CT and I haven't heard of anyone working on it. Others answers are correct:<br clear="none"></div>- it's easy to simulate helical CBCT by playing with the <a rel="nofollow" shape="rect" target="_blank" href="http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html">geometry</a>. I guess compared to a circular geometry where only source-to-detector and source-to-isocenter distances matter, you'll have to adjust the SourceOffsetY and the ProjectionOffsetY. That should work for shepp logan type of simulations and forward projections of 3D images.<br clear="none"></div>- iterative reconstruction should work since we don't have any prior on the geometry except we use the displaced detector for weighting the central area when required. You probably want to do something similar in the direction of the axis of rotation to have smooth transitions between projections but it's theoretically not mandatory (we found the result is better in practice).<br clear="none"></div>- there is no analytical reconstruction available.<br clear="none"></div>Good luck and don't hesitate to contribute if you do some tests.<br clear="none"></div>Simon<br clear="none"></div><div class="yiv2579130402gmail_extra"><br clear="none"><div class="yiv2579130402gmail_quote">On Thu, Feb 26, 2015 at 10:33 PM, louie L <span dir="ltr"><<a rel="nofollow" shape="rect" ymailto="mailto:ghostcz@hotmail.com" target="_blank" href="mailto:ghostcz@hotmail.com">ghostcz@hotmail.com</a>></span> wrote:<br clear="none"><blockquote class="yiv2579130402gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="yiv2579130402yqt9831701123" id="yiv2579130402yqt00626"><div><div>Hi,</div><div><br clear="none"></div><div>You can change the geometry. If changed correctly, most, if not all, the iterative cone beam reconstruction will work. </div><div><br clear="none"></div><div>Best regards,</div><div>Louie<br clear="none"><br clear="none">Greetings from my iOS!</div><div><div class="yiv2579130402h5"><div><br clear="none">On 26 Feb 2015, at 21:19, Robert Calließ <<a rel="nofollow" shape="rect" ymailto="mailto:robert.calliess@gmx.de" target="_blank" href="mailto:robert.calliess@gmx.de">robert.calliess@gmx.de</a>> wrote:<br clear="none"><br clear="none"></div><blockquote type="cite"><div><div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">Hello Vahid,<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">I think you need to add a new reconstruction filter for it. For the first projection the object usually is placed so that the<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">resulting projection image covers the upper half of the detector. And you will need some additional handling (z-increment).<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">I guess you could do a little work around with the current rtk. If you only reconstruct an rectangular roi around<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">the detector’s center where the perspective distortion (because of the cone) is minimal. And then you add these<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">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<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">but with a wider sensor array.<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;"><u></u> <u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">I do not know the code in detail, but if it were possible to have seperate geometry settings for every projection image it <u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">would be possible to model the helical trajectory by the changing geometry without changing /adding code.<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;"><u></u> <u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">But let’s see what grandmasters of RTK will suggest.<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;"><u></u> <u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">Best regards,<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;">Robert<u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;"> <u></u><u></u></span></div><div class="yiv2579130402MsoNormal"><span style="font-size:11.0pt;"><u></u> <u></u></span></div><div><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm;"><div class="yiv2579130402MsoNormal"><b><span style="font-size:10.0pt;">Von:</span></b><span style="font-size:10.0pt;"> Rtk-users [<a rel="nofollow" shape="rect" ymailto="mailto:rtk-users-bounces@public.kitware.com" target="_blank" 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 clear="none"><b>Gesendet:</b> Donnerstag, 26. Februar 2015 20:35<br clear="none"><b>An:</b> <a rel="nofollow" shape="rect" ymailto="mailto:rtk-users@public.kitware.com" target="_blank" href="mailto:rtk-users@public.kitware.com">rtk-users@public.kitware.com</a><br clear="none"><b>Betreff:</b> [Rtk-users] Helical cone-beam reconstruction with RTK<u></u><u></u></span></div></div></div><div class="yiv2579130402MsoNormal"><u></u> <u></u></div><div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">Dear RTK users,<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="margin-bottom:12.0pt;background:white;"><span style="font-size:10.5pt;"><u></u> <u></u></span></div></div><div><div><div><div><div><div><div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;"><u></u> <u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">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.<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">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?<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">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.<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;"><u></u> <u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">Sincerely,<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;">Vahid<u></u><u></u></span></div></div><div><div class="yiv2579130402MsoNormal" style="background:white;"><span style="font-size:10.5pt;"> <u></u><u></u></span></div></div></div></div></div><div class="yiv2579130402MsoNormal" style="margin-bottom:12.0pt;background:white;"><span style=""><u></u> <u></u></span></div></div></div></div></div></div></div></div></blockquote></div></div><blockquote type="cite"><div><span>_______________________________________________</span><br clear="none"><span>Rtk-users mailing list</span><br clear="none"><span><a rel="nofollow" shape="rect" ymailto="mailto:Rtk-users@public.kitware.com" target="_blank" href="mailto:Rtk-users@public.kitware.com">Rtk-users@public.kitware.com</a></span><br clear="none"><span><a rel="nofollow" shape="rect" target="_blank" href="http://public.kitware.com/mailman/listinfo/rtk-users">http://public.kitware.com/mailman/listinfo/rtk-users</a></span><br clear="none"></div></blockquote></div></div><br clear="none">_______________________________________________<br clear="none">
Rtk-users mailing list<br clear="none">
<a rel="nofollow" shape="rect" ymailto="mailto:Rtk-users@public.kitware.com" target="_blank" href="mailto:Rtk-users@public.kitware.com">Rtk-users@public.kitware.com</a><br clear="none">
<a rel="nofollow" shape="rect" target="_blank" href="http://public.kitware.com/mailman/listinfo/rtk-users">http://public.kitware.com/mailman/listinfo/rtk-users</a><br clear="none">
<br clear="none"></blockquote></div><br clear="none"></div></div></div><br><div class="yqt9831701123" id="yqt38578">_______________________________________________<br clear="none">Rtk-users mailing list<br clear="none"><a shape="rect" ymailto="mailto:Rtk-users@public.kitware.com" href="mailto:Rtk-users@public.kitware.com">Rtk-users@public.kitware.com</a><br clear="none"><a shape="rect" href="http://public.kitware.com/mailman/listinfo/rtk-users" target="_blank">http://public.kitware.com/mailman/listinfo/rtk-users</a><br clear="none"></div><br><br></div> </div> </div> </div> </div></body></html>