[Rtk-users] orientation messed up in cbct recon

[Simon Rit]

Hi,
I think you should refer to the geometry documentation:
http://www.openrtk.org/Doxygen/DocGeo3D.html
In RTK, the rotation axis is y (whereas it's z in Dicom). So there is
probably nothing wrong...
Simon

On Wed, May 11, 2022 at 4:03 PM Howard <lomahu at gmail.com> wrote:

> Hi,
>
> I had some geometric questions about the CBCT reconstruction, but this
> time it is the orientation of the reconstructed CBCT.
>
> I attempted to reconstruct CBCT with rtkfdk using the Gate generated Monte
> Carlo projection data, but after the reconstruction the axial view becomes
> a coronal view. Something is wrong in my reconstruction, either with
> rtksimulatedgeometry or with rtkfdk. Here is the detail about the geometry
> and the reconstruction commands.
>
> 1) Simulation set up:
>
> a cylindrical phantom (radius=8mm, height=20mm) sitting on a turntable
> X-ray source to isocenter (center of the cylindrical phantom) = 80mm (SAD)
> Flat panel imager (60mm x 60mm) to isocenter = 80mm (SDD=160mm)
>
> x direction: perpendicular to y direction which is the direction from
> detector to X-ray source;
> z direction: turntable rotation axis and pointing upward
>
> 2) rtksimulatedgeometry was used to generate the geometry xml file
> following the simulation geometry:
> rtksimulatedgeometry -n 360 -o geo.xml --sid 80 -sdd 160 --proj_iso_x -30
> --proj_iso_y -30
>
> 3) rtkfdk was used to reconstruct the CBCT image:
> rtkfdk -g geo.xml -p . -r proj_360.mha -o test.mha --spacing 0.1,0.1,0.2
> --dimension 160,160,100 --origin -8,-8,-10
>
> The projection data and reconstructed CBCT are attached for your info.
> Could anyone help spot what was wrong? Any suggestions or comments are
> appreciated.
>
> Howard
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