[Castor-users] Flat images

[Thibaut Merlin]

  Hello Sadek,

It could be due to the update factors of your data being too low for the
optimizer thresholds during the first iterations. These thresholds (which
can be changed in /conf/optimizer// depending on the algorithm you use) are
there to avoid division by 0 or voxels being trapped in a very low value.
This could happen with datasets with low statistic, or if the values in
your sensitivity image are high in comparison with the image-based
correction values of the first updates. In this case, using an appropriate
calibration factor in your datafile header could improve this.

Hope this helps!
Thibaut

Sadek Nehmeh <san2028 at med.cornell.edu> a écrit :

> Dear All,
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>    I wish everyone a happy and prosperous 2021!
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>    At many occasions, I get flat images (same small value for all pixels
> in the FOV). Sometimes this gets fixed after few iterations. Is anyone
> getting similar issues? Any reason or fix for that?
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>    Thanks,
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>    Sadek
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