[Rtk-users] fdk artefact, sourceOffsetY

[Mathieu DUPONT]

Hello rtk users, 

I try to use RTK for reconstruction in my lab but I encounter some problems.

I try to reconstruct a simulated spheroid. I join my phantom text file (SheppLogan.txt). 

If I set source_y=0, I get a correct (I guess) reconstruction, see the joined figure1.png. I use the followind set of commands :

rtksimulatedgeometry -n 180 --sdd=508.1658133423730 --sid=242.7169928585076  --proj_iso_x=-53.500206362627239 --proj_iso_y=-10.768620138555379   --source_y=0     -o geometry.xml && rtkprojectgeometricphantom -g geometry.xml -o /tmp/tmpfs/projections.mha --spacing 1 --dimension 512 --phantomfile SheppLogan.txt && rtkfdk -v  -p /tmp/tmpfs/  -r projections.mha -o /tmp/tmpfs/fdk_ccd.mha -g geometry.xml --spacing 0.07 --origin -20,14,-20 --dimension 600,600,600 --hardware="cuda"

But If I set source_y=15, I obtain some strange artefacts as you can see on figure2.png. Do you know the origin of this pattern (the vertical one) ? Is it normal ? Or my geometry is completely wrong ? If I use  rtksart, this artefact doesn't exist. 

Thanks in advance and thanks for this nice toolkit. 

regards,
Mathieu Dupont





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Phantom

// original 3D phantom

// -------------------

[Ellipsoid]  A=3      B=3	C=3        x=12.35         y=12.29   	z=-.1 	    beta=0         gray=.20

[Ellipsoid]  A=3     B=3	C=3        x=12.57         y=30.10   	z=-.026 	    beta=0         gray=.20

[Ellipsoid]  A=3      B=3	C=3        x=12.51         y=40.39   	z=-.006 	    beta=0         gray=.20