[gate-users] misaligned voxel sources

[Mutanga Theodore]

Greetings GATErs

I have a small observation using GATE 2.1.0 and voxelized sources.

I have followed the instructions as stated on the site placing first my
phantom at the senter of the FOV with the commands:

/gate/nema_phan/interfileReader/readFile nemaIQphantom.h33
/gate/nema_phan/placement/setTranslation  0. 0. 0. mm
/gate/nema_phan/placement/setRotationAxis 1 0 0
/gate/nema_phan/placement/setRotationAngle 0 deg
/gate/nema_phan/attachVoxelPhantomSD


and then the source was placed as :

/gate/source/voxel_brain/gps/monoenergy 0.511 MeV
/gate/source/voxel_brain/setPosition  -156.738201 -124.511655 -75.21 mm
/gate/source/voxel_brain/gps/confine NULL


My interfile image nemaIQphantom.h33 is of dimensions :

!number of images/energy window := 47
!process status := Reconstructed
!matrix size [1] := 321
!matrix size [2] := 255
       .....
scaling factor (mm/pixel) [1] := +9.765620e-01
scaling factor (mm/pixel) [2] := +9.765620e-01
       ...
slice thickness (pixels) := +3.348482e+00

Now following the information on the User's guide about shifting the
source over half of its distance and using my image dimensions I
calculated the positions as found above.

What I noticed with the reconstructed image was a slight rotation about
the z axix as you can see in the attached photo. I would really like to
know what is goin on if someone has had a simillar experience it will be
nice to share.

Cheers

Theo
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