<html>
<head>
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Dear Robert,</p>
<p>Your description of the trajectory is very obscure to me. Maybe
you have a very unusual X-ray system. Could you make the following
points clear : <br>
</p>
<p>- what is a PCB ? <br>
</p>
<p>- what is fixed/moving in your system (we need this information
for the object, the source and the detector), and what kind of
trajectories have the moving parts ?<br>
</p>
<p>- can you re-draw your sketch with just 2 or 3 positions
(ideally, on similar but separate drawings), each one with the
object, the source and the detector ?</p>
<p>If you do that, we should have a clear understanding of how your
acquisition goes, and be able to give you appropriate advice.</p>
<p>Best regards,</p>
<p>Cyril<br>
</p>
<br>
<div class="moz-cite-prefix">On 10/10/2017 15:02, Robert Calliess
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:002101d341c8$04b34b00$0e19e100$@gmx.de">
<meta http-equiv="Content-Type" content="text/html;
charset=windows-1252">
<meta name="Generator" content="Microsoft Word 14 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"\@SimSun";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.E-MailFormatvorlage17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 2.0cm 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span lang="EN-US">Hello rtk users,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I have question to the
RTK FDK Filter. As far as I understand from to the fourier
slice theorem the object to be reconstructed needs a
circular trajectory and needs to rotate its own centre.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Please have a look at
the attached sketch. With this planar trajectory (Object, a
PCB, is moved on a circle trajectpry “in-plane”, PCB itself
is not rotating) do I need<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">a special filtering if I
want to use FDK for planar CT with respect to the sketched
trajectory ? I tried a circular in-plane trajectory where
the PCB is centred and rotates<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">around its centre point.
And with 100 projections I get good results. But with the
trajectory I described (sketch, attached image) the results
are not so good.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Because of the row-wise
ramp filter It looks like there is a directional dependency.
My assumption is, and with respect to fourier slice theorem,
that the missing object<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">rotation (rotation
around itself) causes there directional effects.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So my questions to the
experts are. Do I need to apply a special filtering before
backprojecting with FDK or is it just the wrong<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">algorithm for this kind
of trajectory ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Robert C.<o:p></o:p></span></p>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Rtk-users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Rtk-users@public.kitware.com">Rtk-users@public.kitware.com</a>
<a class="moz-txt-link-freetext" href="http://public.kitware.com/mailman/listinfo/rtk-users">http://public.kitware.com/mailman/listinfo/rtk-users</a>
</pre>
</blockquote>
<br>
</body>
</html>