[Rtk-users] Lateral blur in a FDK reconstructed volume

[Vincent Libertiaux]

On 11.05.22 15:15, Simon Rit wrote:
> Hi,
> 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.
> http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html#a0fb1475ed76a28cde24fac85eae18e1e
> and then check the resulting angles and distances.
> Simon
>
> On Wed, May 11, 2022 at 2:15 PM Vincent Libertiaux <vl at xris.eu> wrote:
>
>     On 10.05.22 22:54, Simon Rit wrote:
>     > Hi Vincent,
>     > RTK can parametrize any orientation of the detector with the three
>     > angles GantryAngle, InPlaneAngle, OutOfPlaneAngle. 0.025° seems
>     very
>     > small indeed! I don't know how much you know about software B
>     but the
>     > easiest would be to have either the projection matrix or the source
>     > position, detector position, u axis and v axis in patient/object
>     > coordinates to derive the RTK parameters.
>     > Good luck with this!
>     > Simon
>
>     Hi Simon !
>
>     Unfortunately, I don't have access to B projection matrices.
>
>     As for the detector orientation in RTK, I have made this picture
>     to make
>     sure I understand properly how to use the gantry angle to achieve my
>     desired geometry:
>
>     https://ibb.co/J3H8z9M
>
>     The cyan detector is the default configuration with a 0° gantry
>     angle.
>     The blue detector is at a gantry angle of alpha (largely
>     exaggerated for
>     the sake of clarity).  So in order to simulate an out-of-plane
>     rotation
>     of the detector around its vertical axis, I should translate this
>     blue
>     detector so that its center matches the coordinates of the cyan
>     one, and
>     translate the source accordingly (along the black vectors on the
>     picture) ?  I assume that proj_iso_x/y and source_x/y are
>     expressed in
>     the gantry system of coordinates (local) ?
>
>
>     Thank you again for your feedback,
>
>     kindest regards,
>
>     V.
>
Thanks Simon,

I'll investigate more and let you know.  Hopefully, it might be useful 
to someone else one day !

V.
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