[Rtk-users] Reducing the pattern of errors

[anais.capouillez at student.uliege.be]

Hi,

When I use FDK to reconstruct my volume, there are some parts inside the volume where the error is up to 10%, even in the middle of my volume. When I compute the difference between the phantom and the reconstructed object I can see some patterns of small lines where the error is way bigger than in the rest of the volume.
I need to reconstruct my volume with at least one big area with no error bigger than few percents of error for each voxel of the area. The patterns of errors occur too often to select an area sufficiently big.
Unfortunately, I cannot change the number of projections I use because this is imposed to me.

Therefore, I want to know if it is possible to obtain better results with FDK or if I have to use an iterative algorithm.



For the parameters of the geometry, I used 180 projections, sdd=978.5, and sid=478.5. For the projections I used a spacing of 0.8 and a dimension of 1024. And for the reconstruction, I used a spacing of 0.5, and a dimension of 204*404*204.

I joined two screenshots of the absolute difference between the phantom and the reconstruction (one zoomed on some of the small lines of error, and another one not zoomed).


If you want the images of my phantom, the reconstruction, and the absolute difference between the two (with the actual values and with relative values), I uploaded them here: https://drive.google.com/drive/folders/194k2CDomeLlmVxybTllSKWYhpCZyPvVx?usp=sharing


Thank you.

Anaïs
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