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<p>Dear Robert,</p>
<p>Could you send two datasets of projections, one for each case ?
We would have a look at them and it would help us understand your
trajectories. The drawings you sent do not seem to be sufficient
to remove all ambiguities.<br>
</p>
<p>Best regards,</p>
<p>Cyril<br>
</p>
<br>
<div class="moz-cite-prefix">On 25/10/2017 09:03, "Robert Calließ"
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:trinity-32181a21-bb6b-42aa-9de0-5fcccf241521-1508915009840@3c-app-gmx-bs43">
<div style="font-family: Verdana;font-size: 12.0px;">
<div>
<div>Hello,</div>
<div>the object is moving on a circular path. There are arrows
between the different detector positions showing the</div>
<div>moving direction. The source is static. </div>
<div> </div>
<div>Kind regards,</div>
<div>Robert</div>
<div>
<div style="margin: 10.0px 5.0px 5.0px 10.0px;padding:
10.0px 0 10.0px 10.0px;border-left: 2.0px solid
rgb(195,217,229);">
<div style="margin: 0 0 10.0px 0;"><b>Gesendet:</b> Dienstag,
24. Oktober 2017 um 16:47 Uhr<br>
<b>Von:</b> "Simon Rit"
<a class="moz-txt-link-rfc2396E" href="mailto:simon.rit@creatis.insa-lyon.fr"><simon.rit@creatis.insa-lyon.fr></a><br>
<b>An:</b> "Robert Calließ"
<a class="moz-txt-link-rfc2396E" href="mailto:Robert.Calliess@gmx.de"><Robert.Calliess@gmx.de></a><br>
<b>Cc:</b> <a class="moz-txt-link-rfc2396E" href="mailto:rtk-users@public.kitware.com">"rtk-users@public.kitware.com"</a>
<a class="moz-txt-link-rfc2396E" href="mailto:rtk-users@public.kitware.com"><rtk-users@public.kitware.com></a><br>
<b>Betreff:</b> Re: Re: [Rtk-users] FDK for planar ct</div>
<div>
<div>
<div>
<div>Hi,</div>
I see one drawing only, not two. And the object does
not seem to be moving on your drawing, is it? If not
and the source is also static (as it seem), this is
equivalent to one large projection.</div>
Simon</div>
<div class="gmail_extra">
<div class="gmail_quote">On Tue, Oct 24, 2017 at 3:58
PM, "Robert Calließ" <span><<a
href="mailto:Robert.Calliess@gmx.de"
onclick="parent.window.location.href='Robert.Calliess@gmx.de';
return false;" target="_blank"
moz-do-not-send="true">Robert.Calliess@gmx.de</a>></span>
wrote:
<blockquote class="gmail_quote" style="margin: 0 0 0
0.8ex;border-left: 1.0px rgb(204,204,204)
solid;padding-left: 1.0ex;">
<div>
<div style="font-family: Verdana;font-size:
12.0px;">
<div>Hello,</div>
<div>I suppose there are still
misunderstandings with respect to the
trajectory.</div>
<div>Attached you can find the two difference
trajectories. I also had a closer look to</div>
<div>the off centered fdk ( the paper you
suggested). But I don't think it is in my
case.</div>
<div>The iso ray passes object center and
detector center at each view. Off centered
fdk</div>
<div>has a different preweighting scheme.</div>
<div> </div>
<div>You said that the RTK ramp filter is
along the u axis (orthogonal to rotaion
axis). For planar_ct_1 trajectory that</div>
<div>should fit. As you can see at the
picture, the object is moving on a circular
path but not rotating around the</div>
<div>center point (red cross in the image).</div>
<div> </div>
<div> </div>
<div>Kind regards,</div>
<div>Robert C.</div>
<div>
<div style="margin: 10.0px 5.0px 5.0px
10.0px;padding: 10.0px 0 10.0px
10.0px;border-left: 2.0px solid
rgb(195,217,229);">
<div style="margin: 0 0 10.0px 0;"><b>Gesendet:</b> Donnerstag,
12. Oktober 2017 um 07:14 Uhr<br>
<b>Von:</b> "Simon Rit" <<a
href="mailto:simon.rit@creatis.insa-lyon.fr"
onclick="parent.window.location.href='simon.rit@creatis.insa-lyon.fr';
return false;" target="_blank"
moz-do-not-send="true">simon.rit@creatis.insa-lyon.fr</a>><br>
<b>An:</b> "Robert Calliess" <<a
href="mailto:robert.calliess@gmx.de"
onclick="parent.window.location.href='robert.calliess@gmx.de';
return false;" target="_blank"
moz-do-not-send="true">robert.calliess@gmx.de</a>><br>
<b>Cc:</b> "<a
href="mailto:rtk-users@public.kitware.com"
onclick="parent.window.location.href='rtk-users@public.kitware.com';
return false;" target="_blank"
moz-do-not-send="true">rtk-users@public.kitware.com</a>"
<<a
href="mailto:rtk-users@public.kitware.com"
onclick="parent.window.location.href='rtk-users@public.kitware.com';
return false;" target="_blank"
moz-do-not-send="true">rtk-users@public.kitware.com</a>>
<div>
<div class="h5"><br>
<b>Betreff:</b> Re: [Rtk-users] FDK
for planar ct</div>
</div>
</div>
<div>
<div class="h5">
<div>
<div>
<div>
<div>
<div>
<div>Hello,</div>
No. The filter should be
orthogonal to the rotation
axis. The RTK ramp filter
is along the u axis of the
projection.</div>
Trajectory 2: if you take
photos by rotating the
cameras, they are
photographies of the same
point-of-view. This is what I
meant.</div>
Cheers,</div>
Simon</div>
<div class="gmail_extra">
<div class="gmail_quote">On Wed,
Oct 11, 2017 at 8:58 PM, Robert
Calliess <span><<a
href="mailto:robert.calliess@gmx.de"
onclick="parent.window.location.href='robert.calliess@gmx.de'; return
false;" target="_blank"
moz-do-not-send="true">robert.calliess@gmx.de</a>></span>
wrote:
<blockquote class="gmail_quote"
style="margin: 0 0 0
0.8ex;border-left: 1.0px
rgb(204,204,204)
solid;padding-left: 1.0ex;">
<div>
<div
class="m_-55466648088813648m_5269510085608132824WordSection1">
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">Hello,</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">thanks
for the link to the
paper but I dont have
access to it. Aside
from how the
trajectory is
interpreted within in
RTK. My actual
question was</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">if
any of those two
trajectories would
need another
reconstruction filter
than the FDK Filter.
From my point of
understanding a
specific rotation
around</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">the
object is necessary
for fbp/fdk (like
c-arm bow, standard
circular cone-beam
trajectory). That’s
why I asked If the
first trajectory needs
some other
reconstruction </span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">filter
because the object
itself doesn’t rotate
around itself. It
actually gets
translated on a
circular path. So I
was more expecting a
“yes” or “no” to the
fdk filter </span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">or a
hint to another filter
(except iterative
reconstructions) I
should use for these
trajectories.</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);"> </span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">To
trajectory 2: I think
the projections are
different. The object
rotates and each
projection shows a
different view.</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);"> </span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);"> </span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">Kind
regards,</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);">Robert
C.</span></p>
<p class="MsoNormal"><span
style="font-size:
11.0pt;font-family:
Calibri ,
sans-serif;color:
rgb(31,73,125);"> </span></p>
<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;">
<a
href="mailto:simon.rit@gmail.com"
onclick="parent.window.location.href='simon.rit@gmail.com'; return
false;"
target="_blank"
moz-do-not-send="true">simon.rit@gmail.com</a>
[mailto:<a
href="mailto:simon.rit@gmail.com"
onclick="parent.window.location.href='simon.rit@gmail.com'; return
false;"
target="_blank"
moz-do-not-send="true">simon.rit@gmail.com</a>]
<b>Im Auftrag von </b>Simon
Rit<br>
<b>Gesendet:</b>
Dienstag, 1</span><span
style="font-size:
10.0pt;font-family:
Tahoma , sans-serif;">0.
Oktober 2017 20:29<br>
<b>An:</b> Robert
Calliess</span></p>
<div>
<div
class="m_-55466648088813648h5"><br>
<b>Cc:</b> Cyril Mory;
<a
href="mailto:rtk-users@public.kitware.com"
onclick="parent.window.location.href='rtk-users@public.kitware.com';
return false;"
target="_blank"
moz-do-not-send="true">rtk-users@public.kitware.com</a><br>
<b>Betreff:</b> Re:
[Rtk-users] FDK for
planar ct</div>
</div>
<p> </p>
<div>
<div
class="m_-55466648088813648h5">
<p class="MsoNormal"> </p>
<div>
<div>
<div>
<div>
<p
class="MsoNormal">Hi,</p>
</div>
<p
class="MsoNormal">Let
me try to
clarify what I
mean by
"source
trajectory wrt
the object."
In tomography,
you need to
determine the
source
trajectory in
the object
coordinate
system, we
don't really
care about the
source
trajectory in
the room
coordinate
system. For
example,
rotating the
source on a
circular
trajectory or
rotating the
object makes
no difference
for the
reconstruction
algorithm.
That's why we
call
diagnostic
scanners
"helical
scanners".</p>
</div>
<p
class="MsoNormal">So
for trajectory
1, it seems that
the source
trajectory
(again, wrt to
the object) is a
circle but the
object is
offset. This is
somewhat similar
to <a
href="https://doi.org/10.1109/TNS.2006.880977"
target="_blank" moz-do-not-send="true">https://doi.org/10.1109/TNS.2006.880977</a>
except that the
detector is not
tilted so FDK
would be the
only FBP
algorithm I
could think of.
But the
situation is
really not good,
data are missing
and iterative
reconstruction
should give
better results.</p>
</div>
<div>
<p
class="MsoNormal">Trajectory
2: what I said
in my previous
email is true,
it's useless I
believe, all
projections are
similar up to a
2D transform of
the projection.</p>
</div>
<div>
<p
class="MsoNormal">Simon</p>
</div>
</div>
<div>
<p class="MsoNormal"> </p>
<div>
<p
class="MsoNormal">On
Tue, Oct 10,
2017 at 8:07 PM,
Robert Calliess
<<a
href="mailto:robert.calliess@gmx.de"
onclick="parent.window.location.href='robert.calliess@gmx.de'; return
false;"
target="_blank"
moz-do-not-send="true">robert.calliess@gmx.de</a>> wrote:</p>
<div>
<div>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Hello,</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">I
try to clarify
the both
trajectories.</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Trajectory
1:</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">No,
i dont move
the source on
two circles.
The xray
source is
fixed. Only
the object and
the detector
moves. Both
move on a
circular path
so that the
iso-ray</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">always
passes through
the pcb centre
and the
detector
centre. There
is one
orthogonal
view and the
others are the
ones moving on
the circular
path. </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">(Object
is not
rotating
around its own
axis).</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Trajectory
2:</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Yes,
the xray
source lies in
the rotation
axis and only
the object
rotates around
its z-axis.
Detector and
xray source
are fixed and
the detector
is tilted.</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">It’s
almost like
this
trajectory
here <a
href="https://www.ikeda-shoponline.com/engctsoft/wp-content/uploads/2016/06/Oblique-View-CT1.jpg"
target="_blank" moz-do-not-send="true">https://www.ikeda-shoponline.com/engctsoft/wp-content/uploads/2016/06/Oblique-View-CT1.jpg</a></span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">except
that the xray
source lies on
the rotation
axis.</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">I
hope this
helps to
understand the
trajectories I
have to deal
with.</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Kind
regards, </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);">Robert</span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<p
class="MsoNormal"><span
style="font-size: 11.0pt;font-family: Calibri , sans-serif;color:
rgb(31,73,125);"> </span></p>
<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;"> <a
href="mailto:simon.rit@gmail.com"
onclick="parent.window.location.href='simon.rit@gmail.com'; return
false;"
target="_blank"
moz-do-not-send="true">simon.rit@gmail.com</a> [mailto:<a
href="mailto:simon.rit@gmail.com"
onclick="parent.window.location.href='simon.rit@gmail.com'; return
false;"
target="_blank"
moz-do-not-send="true">simon.rit@gmail.com</a>] <b>Im Auftrag von </b>Simon
Rit<br>
<b>Gese</b></span><b><span
style="font-size: 10.0pt;font-family: Tahoma , sans-serif;">ndet:</span></b><span
style="font-size: 10.0pt;font-family: Tahoma , sans-serif;"> Dienstag,
10. Oktober
2017 19:06<br>
<b>An:</b>
Robert Calließ<br>
<b>Cc:</b>
Cyril Mory; <a
href="mailto:rtk-users@public.kitware.com"
onclick="parent.window.location.href='rtk-users@public.kitware.com';
return false;"
target="_blank" moz-do-not-send="true">rtk-users@public.kitware.com</a></span></p>
<div>
<div>
<p
class="MsoNormal"><br>
<b>Betreff:</b>
Re:
[Rtk-users]
FDK for planar
ct</p>
</div>
</div>
<div>
<div>
<p
class="MsoNormal"> </p>
<div>
<div>
<div>
<div>
<div>
<div>
<p
class="MsoNormal">Hi,</p>
</div>
<p
class="MsoNormal">It's
still not
clear to me
but what is
helpful is to
think in terms
of source
trajectory wrt
the object.</p>
</div>
<p
class="MsoNormal">Trajectory
1: if I
understand,
you move the
source on two
circles plus
one point. I
don't know of
a FBP
algorithm to
reconstruct
this, but
there might be
one. I would
consider
iterative
reconstruction
first.</p>
</div>
<p
class="MsoNormal">Trajectory
2: your
trajectory is
a point, the
source does
not move with
respect ot the
object since
it lies on the
rotation axis.
So each
projection
contains
exactly the
same
information up
to a simple 2D
projection
deformation.
So it's
hopeless to
reconstruct
from one
projection
only.</p>
</div>
<div>
<p
class="MsoNormal">To
create the
correct
geometry, I
would suggest
using the
function <a
href="https://github.com/SimonRit/RTK/blob/master/code/rtkThreeDCircularProjectionGeometry.h#L92"
target="_blank" moz-do-not-send="true">AddProjection</a> for which you
provide the
source and
detector
positions plus
the 3D
coordinates of
the two axes
of the
coordinate
system of the
projection.</p>
</div>
<p
class="MsoNormal">I
hope this
helps</p>
</div>
<p
class="MsoNormal">Simon</p>
</div>
<div>
<p
class="MsoNormal"> </p>
<div>
<p
class="MsoNormal">On
Tue, Oct 10,
2017 at 5:43
PM, "Robert
Calließ" <<a
href="mailto:Robert.Calliess@gmx.de"
onclick="parent.window.location.href='Robert.Calliess@gmx.de';
return false;"
target="_blank" moz-do-not-send="true">Robert.Calliess@gmx.de</a>>
wrote:</p>
<div>
<div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Hello,</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">thank you
for the fast
reply.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">To answer
your questions
first.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">In this case
the
abbrevation
pcb stands for
printed
circuit board.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Next point
is the
trajectory we
are currently
handling with.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Please see
the attached
image
"trajectory.png".
There are two
schematics
showing the
side view and
top view for
trajectory
type 1</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">and a
side-view for
trajectory
type 2.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">For type 1:</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">The xray
source is
fixed. The pcb
is clamped
within a
transport, so
the pcb and
the detector
are moveable
with in the xy
plane.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">As you can
see at the
image, the pcb
moves along
a circular
path but the
pcb itself is
not rotating.
And let's
assume that
the iso ray</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">always
passes through
the centre of
the pcb and
the centre of
the detector.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">For type 2:</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">The xray
source is
fixed and the
detector is
tilted. The
pcb lies
centred in the
middle of a
table. So that
the pcb
rotates around
its centre</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">around the
z-axis.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">I hope this
makes clear
what
trajectory i'm
dealing with.
Thank you.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Kind
regards,</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Robert C.</span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div>
<p
class="MsoNormal"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
</div>
<div
style="border:
none;border-left: solid rgb(195,217,229) 1.5pt;padding: 0.0cm 0.0cm
0.0cm
8.0pt;margin-left:
7.5pt;margin-top: 7.5pt;margin-right: 3.75pt;margin-bottom: 3.75pt;">
<div
style="margin-bottom:
7.5pt;">
<p
class="MsoNormal"><b><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Gesendet:</span></b><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> Dienstag,
10. Oktober
2017 um 15:31
Uhr<br>
<b>Von:</b> "Cyril
Mory" <<a
href="mailto:cyril.mory@creatis.insa-lyon.fr"
onclick="parent.window.location.href='cyril.mory@creatis.insa-lyon.fr';
return false;"
target="_blank" moz-do-not-send="true">cyril.mory@creatis.insa-lyon.fr</a>><br>
<b>An:</b> "Robert
Calliess" <<a
href="mailto:robert.calliess@gmx.de"
onclick="parent.window.location.href='robert.calliess@gmx.de';
return false;"
target="_blank" moz-do-not-send="true">robert.calliess@gmx.de</a>>, <a
href="mailto:rtk-users@public.kitware.com"
onclick="parent.window.location.href='rtk-users@public.kitware.com';
return false;"
target="_blank" moz-do-not-send="true">rtk-users@public.kitware.com</a><br>
<b>Betreff:</b> Re:
[Rtk-users]
FDK for planar
ct</span></p>
</div>
<div>
<div>
<div>
<div>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Dear Robert,</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">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 :</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">- what is a
PCB ?</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">- 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 ?</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">- 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 ?</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">If you do
that, we
should have a
clear
understanding
of how your
acquisition
goes, and be
able to give
you
appropriate
advice.</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Best
regards,</span></p>
<p
style="background:
white;"><span
style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Cyril</span></p>
<p
class="MsoNormal"
style="background: white;"><span style="font-size: 9.0pt;font-family:
Verdana ,
sans-serif;">
</span></p>
<div>
<p
class="MsoNormal"
style="background: white;"><span style="font-size: 9.0pt;font-family:
Verdana ,
sans-serif;">On
10/10/2017
15:02, Robert
Calliess
wrote:</span></p>
</div>
<blockquote
style="margin-top:
5.0pt;margin-bottom: 5.0pt;">
<div>
<p
class="MsoNormal"
style="background: white;">Hello rtk users,</p>
<p
class="MsoNormal"
style="background: white;">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.</p>
<p
class="MsoNormal"
style="background: white;">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</p>
<p
class="MsoNormal"
style="background: white;">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</p>
<p
class="MsoNormal"
style="background: white;">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.</p>
<p
class="MsoNormal"
style="background: white;">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</p>
<p
class="MsoNormal"
style="background: white;">rotation (rotation around itself) causes
there
directional
effects.</p>
<p
class="MsoNormal"
style="background: white;"> </p>
<p
class="MsoNormal"
style="background: white;">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</p>
<p
class="MsoNormal"
style="background: white;">algorithm for this kind of trajectory ?</p>
<p
class="MsoNormal"
style="background: white;"> </p>
<p
class="MsoNormal"
style="background: white;">kind regards,</p>
<p
class="MsoNormal"
style="background: white;">Robert C.</p>
</div>
<p
class="MsoNormal"
style="background: white;"><span style="font-size: 9.0pt;font-family:
Verdana ,
sans-serif;">
</span></p>
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