[Rtk-users] Help required - rtkFDK reconstruction

[Simon Rit]

Hi,
Please use the mailing list (cc).
1. The raw format is not directly understandable I believe, you need to
have meta information passed, e.g. with a mhd. Since you know how to
convert your projection images to line integral (for rtkfdk), just use the
input of rtkfdk instead of using the rtk::ProjectionsReader.
2. The output of both rtk::CudaFDKConeBeamReconstructionFilter and
rtk::FDKConeBeamReconstructionFilter is mu if the input projections are
well pre-processed, i.e., if they contain the line integrals of mu.
Simon

On Thu, Nov 19, 2020 at 10:24 AM Febin P Alex <febin.p at panaceamedical.com>
wrote:

> Dear Simon,
>
>
> I'm using the RTK-C++ toolkit for our cbct reconstruction purpose and
> found it very helpful. I'm using the rtkFDK algorithm for reconstruction.
> Currently I'm a facing a couple of issues which are illustrated
>
> 1 . While going through the documentation, I have come across the use of
> water precorrection filter for cupping correction. It's said that we need
> to pass a set of coefficients for the filter to get activated.
>      But we were not able to find a C++ test code detailing how to find
> the coefficients but rather got a python code in the below link.
>
>                    http://wiki.openrtk.org/index.php/WaterPreCorrection
>
>      So I tried to run that python code with my data. I have around 330
> unsigned short projection in *.raw* format each of dimension 1536x1536
> pixels.
>      Since python itk.Image doesn't have support for unsigned short I have
> converted the data to float and given as input to rtk.ProjectioReader
> class.
>      But on execution, it is getting aborted at *fdkFilter.Update()*
> command without throwing any exception. Attaching the modified python code.
>
>
> 2. The second issue is , after the reconstruction I want to convert the
> reconstructed grey level values into CT numbers. For this I'm using the
> equation
>
>                             HU=1000×μ−μwaterμwater−μair,  where
> μ is the linear attenuation coefficient of substance.
>
>     M y doubt is whether the output from
>  rtk::CudaFDKConeBeamReconstructionFilter is same as the  μ defined above
> or any more conversion is required.
>
>
> Kindly request you to suggest me a solution.
>
> Thanks & Regards
> Febin P Alex
>
>
>
>
>
>
>
>
>
>
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