[Rtk-users] Tomosynthesis reconstruction

[Simon Rit]

Hi Shiras,
I generated a volume to look at your problem:
rtkdrawshepploganphantom --like volume.mhd -o volume.mhd --phantomscale 32
--offset 0,0,1.7
Then I obtained the same issue as you. I think the problem is that rtkfdk
is meant for circular CBCT and it includes pre-weighting for displaced
detector and short scan. I'm not sure why you don't get a warning but these
are probably responsible for the blank output. A simple solution is to do
only the 3 FDK steps using in order the command tools:
rtktwodweights
rtkramp
rtkbackprojections
You can also try to shunt the preweighting by modifying rtkfdk.cxx.

It's interesting that you try out tomosynthesis but you'll encounter some
problem. When I ran the above commands, I get very weird results because
the first and the last projections get a lot more weight than the others
since it looks at the angular weight with the previous and the next
projections. A simple solution is to blank out these two projections.
Good luck and keep us posted if you get interesting results,
Simon

On Thu, May 19, 2016 at 10:41 AM, Shiras Abdurahman <shiraska at gmail.com>
wrote:

> Dear all,
>
> I am trying to simulate Tomosynthesis reconstruction with stationary flat
> panel detector where source rotates around Y axis to acquire 21 projections
> (system geometry diagram is attached). Geometry file geometry.xml is
> generated with Reg23ProjectionGeometry. I generated projection images of
> a cube volume and then I tried to reconstruct with FDK algorithm. Even
> though I  am able to generate projections, FDK reconstruction yields the
> volume with all voxel values zero. The commands I used for generating
> projections and reconstructing volume are
>
> rtkforwardprojections -g geometry.xml -o projections.mhd -i volume.mhd
> --spacing 0.1518,0.1518,1 --dimension 1420,1416,21 --fp=CudaRayCast
> rtkfdk -p . -r projections.mhd -o fdk.mhd -g geometry.xml
> --spacing=0.25,0.25,0.25 --origin=-31.875,-31.875,25
> --dimension=256,256,256 --hardware=cuda
>
> I am also attaching geometry xml file, mhd header files of the original
> volume, projections and reconstructed volume.
>
> With regards,
> Shiras
>
>
>
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