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--></style></head><body lang=CS link=blue vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hi,</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I am prety new to RTK, but through I am learning with it I found a issue the is not clear to me. I followed the procedure from <a href="http://wiki.openrtk.org/index.php/RTK/Scripts/3DCG">http://wiki.openrtk.org/index.php/RTK/Scripts/3DCG</a> where I changed few things:</p><p class=MsoNormal><o:p> </o:p></p><ol style='margin-top:0cm' start=1 type=1><li class=MsoListParagraph style='margin-left:0cm;mso-list:l0 level1 lfo1'>I simplified the Shepp Logan file to just simple sphere (in attachement).</li><li class=MsoListParagraph style='margin-left:0cm;mso-list:l0 level1 lfo1'>I generated projections (using output_xml.xml – two whole gantry rotation in two diffferent y offsets) – the xml has been generated via python script (most of it-in attachment) which is reproducing procedure described in <a href="http://www.openrtk.org/Doxygen/DocGeo3D.html">http://www.openrtk.org/Doxygen/DocGeo3D.html</a></li><li class=MsoListParagraph style='margin-left:0cm;mso-list:l0 level1 lfo1'>Then I looked at the projections.mha in VolView (too large to send, please see the screenshot bellow)</li></ol><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My questions are 2:</p><p class=MsoNormal><o:p> </o:p></p><ol style='margin-top:0cm' start=1 type=1><li class=MsoListParagraph style='margin-left:0cm;mso-list:l1 level1 lfo2'>Why there is a shift in Y-Z quadrant in generated projections.mha? It should be perfectly alligned – two of my colleagues has been so kind to check the procedure for me and found no mistake (the sinogram of sphere in the zero position(x=y=z=0) should be symetric perfectly) – what I am doing wrong?</li><li class=MsoListParagraph style='margin-left:0cm;mso-list:l1 level1 lfo2'>I simulated corrected projection byte by byte (into MHA) and then tried to use back-projection (rtkfdk) and Sart (rtksart)-you can see in output_xml.xml that the gantry angle is linear (not between -180° and 180° or between 0° and 360°), because when I put it into -180° and 180° it didn’t reconstruct anything properly – why is it? It is not possible to use same angle value more then once in xml geometry file (even if it has different y shift of detector and source)?</li></ol><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Purpose of this testing is that I am going to reconstruct data from helical CT, but my first attemattempt failed and I am going step by step to find out hat is wrong in my procedure.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I use docker version of RTK given by <a href="http://wiki.openrtk.org/index.php/RTK_wiki_help">http://wiki.openrtk.org/index.php/RTK_wiki_help</a></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thank you…</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Kind regards…</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>p.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><img border=0 width=1068 height=601 style='width:11.125in;height:6.2604in' id="Obrázek_x0020_3" src="cid:image002.png@01D54DC5.D4372EE0"></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>