Dear Simon, Thank you very much for the reply. I tried to reconstruct with only ramp filtering and back projection and the results are looking good without any weighting of the projections. I also reconstructed the volume with rtksart with 10 iterations and the results are better than rtkfdk. With these experiments, I also confirmed that my geometry file is accurate.
Thank you very much for your help. With regards, Shiras On Thu, May 26, 2016 at 6:04 PM, Simon Rit <[email protected]> wrote: > 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 <[email protected]> > 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 >> >> >> >> _______________________________________________ >> Rtk-users mailing list >> [email protected] >> http://public.kitware.com/mailman/listinfo/rtk-users >> >> >
_______________________________________________ Rtk-users mailing list [email protected] http://public.kitware.com/mailman/listinfo/rtk-users
