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<div class="moz-cite-prefix">On 19.07.22 19:21, Jerome Lesaint
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJ-g2_1F70jpMkqYjP0MaiuXAapgKdZPxkHbSueMhnGRxOFmfg@mail.gmail.com">
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<div dir="ltr">Hello all,
<div><br>
</div>
<div>The question of neglecting out-of-plane offsets if less
than 2 degrees is discussed in Yang et al, Med. Phys., 2006,
section III.A.</div>
<div>Regards, <br>
</div>
<div>Jerome</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">Le mar. 19 juil. 2022 à 18:23,
Simon Rit <<a href="mailto:simon.rit@creatis.insa-lyon.fr"
moz-do-not-send="true" class="moz-txt-link-freetext">simon.rit@creatis.insa-lyon.fr</a>>
a écrit :<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>Hi Vincent,</div>
<div>Thanks for the report. I don't believe that there is
need for a PR. It comes down to using a different
parameterization which I think you can always go around
with one of the different versions of AddProjection.</div>
<div>Did I mention that the out of plane angle has no effect
below 2°? If yes, I'm not sure you can trust this
information... as I don't know where it comes from.</div>
<div>Best regards,<br>
</div>
<div>Simon<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jul 19, 2022 at
11:34 AM Vincent Libertiaux <<a
href="mailto:vl@xris.eu" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">vl@xris.eu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div>
<div>On 11.05.22 15:20, Vincent Libertiaux wrote:<br>
</div>
<blockquote type="cite">
<div>On 11.05.22 15:15, Simon Rit wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Hi,</div>
<div>Yes, I think it's correct. To be sure you
correctly understand it, you can always do test
cases with the source and detector positions, u
v vectors in the coordinate system of your
object.</div>
<div><a
href="http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html#a0fb1475ed76a28cde24fac85eae18e1e"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html#a0fb1475ed76a28cde24fac85eae18e1e</a></div>
<div>and then check the resulting angles and
distances.<br>
</div>
<div>Simon<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, May 11,
2022 at 2:15 PM Vincent Libertiaux <<a
href="mailto:vl@xris.eu" target="_blank"
moz-do-not-send="true"
class="moz-txt-link-freetext">vl@xris.eu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px
0px 0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">On 10.05.22
22:54, Simon Rit wrote:<br>
> Hi Vincent,<br>
> RTK can parametrize any orientation of the
detector with the three <br>
> angles GantryAngle, InPlaneAngle,
OutOfPlaneAngle. 0.025° seems very <br>
> small indeed! I don't know how much you
know about software B but the <br>
> easiest would be to have either the
projection matrix or the source <br>
> position, detector position, u axis and v
axis in patient/object <br>
> coordinates to derive the RTK parameters.<br>
> Good luck with this!<br>
> Simon<br>
<br>
Hi Simon !<br>
<br>
Unfortunately, I don't have access to B
projection matrices.<br>
<br>
As for the detector orientation in RTK, I have
made this picture to make <br>
sure I understand properly how to use the gantry
angle to achieve my <br>
desired geometry:<br>
<br>
<a href="https://ibb.co/J3H8z9M"
rel="noreferrer" target="_blank"
moz-do-not-send="true"
class="moz-txt-link-freetext">https://ibb.co/J3H8z9M</a><br>
<br>
The cyan detector is the default configuration
with a 0° gantry angle. <br>
The blue detector is at a gantry angle of alpha
(largely exaggerated for <br>
the sake of clarity). So in order to simulate
an out-of-plane rotation <br>
of the detector around its vertical axis, I
should translate this blue <br>
detector so that its center matches the
coordinates of the cyan one, and <br>
translate the source accordingly (along the
black vectors on the <br>
picture) ? I assume that proj_iso_x/y and
source_x/y are expressed in <br>
the gantry system of coordinates (local) ?<br>
<br>
<br>
Thank you again for your feedback,<br>
<br>
kindest regards,<br>
<br>
V.<br>
<br>
</blockquote>
</div>
</blockquote>
<p>Thanks Simon,</p>
<p>I'll investigate more and let you know. Hopefully,
it might be useful to someone else one day !</p>
<p>V.<br>
</p>
</blockquote>
<p>Hi Simon,</p>
<p>I finally got some time to investigate further this
issue this week. I managed to get sharp edges
everywhere now and it was indeed the detector
out-of-plane angle colinear with the gantry angle that
was the cause. The value given by the other software
seems to have been in rad rather than degrees; the
angle I found was 1.15°. This makes me wonder what
were the assumptions under which no effect was found
for angles below 2°. If you know the title of the
seminal paper, I'd be interested to read it.</p>
<p><br>
</p>
<p>As for the mean to include this angle in the
geometry, no extra code was indeed needed. If we call
this extra angle "c", the following modifications have
to be made in rtksimulatedgeometry:</p>
<p>- first angle = c</p>
<p>- sdd = sdd_0 * cos(c)</p>
<p>- sid = sid_0 * cos(c)</p>
<p>- source_x = source_x0 - sid*sin(c)</p>
<p>- proj_iso_x = proj_iso_x0 + (sdd-sid)*sin(c)</p>
<p>I can't really promise I'll find time to do it, but
if it is the case, I'll submit a PR to include that in
the matrices computation.</p>
<p>Hopefully, it will help others on the list who
encountered a similar issue.<br>
</p>
<p>Best regards,</p>
<p>Vincent<br>
</p>
</div>
</blockquote>
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</blockquote>
</div>
</blockquote>
<p>Thank you very much for the reference Jérôme !</p>
<p>Best regards,</p>
<p>Vincent<br>
</p>
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