Hi, Yes, flat field correction is possible with ITK since it's the log of the division of two images. We do it for example for some data types (for example the XRad small animal scanner, see here <https://github.com/SimonRit/RTK/blob/master/include/rtkXRadRawToAttenuationImageFilter.hxx#L55-L101>). However, Elekta already does a flat field correction in the data which are stored on disk so I'm not sure this is the issue here. Elekta data is processed by applying a lookup table to the raw data https://github.com/SimonRit/RTK/blob/master/include/rtkElektaSynergyRawLookupTableImageFilter.hxx#L27-L60 and assuming that air is at 65536 then (see here <https://github.com/SimonRit/RTK/blob/master/include/rtkProjectionsReader.hxx#L315>). That can be improved but it mimicked what was done in the first versions of XVI. I think it's been improved since but I'm not aware of the detail of the improvements. I hope it helps, Simon
On Thu, Jan 13, 2022 at 1:54 AM 雅之 服部 <masayuki.h.0...@gmail.com> wrote: > Dear rtk-users > > I am now working on iterative reconstruction offset detector CBCT using my > elekta data. > > However, probably because the data is truncated , the ring artifact appears > in the iterative reconstruction. > > One of the reasons was that flat field correction was not performed. > > Is flat field correction possible with RTK? > > I don't have an image for flat field correction, so are you predicting it? Or > do I have to have a flat field correction image? > > Thank you very much in advance > > masa@japan > > [image: recon.jpg] > _______________________________________________ > Rtk-users mailing list > Rtk-users@public.kitware.com > https://public.kitware.com/mailman/listinfo/rtk-users >
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