[Rtk-users] orientation messed up in cbct recon

[Howard]

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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