[Rtk-users] Reconstruction problem of C-arm projections

[Marc Vila Oliva]

Hello Mr. Wang, 

I have tried to reconstruct your data-set using your geometry file and
your projections provided in your DropBox. Considering the number of
projections (292) and the limited angle view (193.1 degrees), I would
say that the results (see attached pictures) are not that bad. Note that
your reconstructed data-set will present truncation due to the truncated
projections that are being used. Therefore you should add a padded value
in order to correct this effect.

One question, how do you pass from your raw images to attenuation
images? In my case I just took the -log of the projections divided by
the max_value (aprox.). I also cropped a bit the projections due to a
high-value frame around the projections. 

Then I ran the following command:

// fdk reconstruction
rtkfdk -p . -r Cropped_minuslogprojections.mhd -g geometry.xml -o
test_hann.mha --dimension 128 --spacing 2 --pad 1.2

// mask fov
rtkfieldofview -p projections/. -r im1_.*.mhd -g geometry.xml -o
test_fov.mha --reconstruction test_hann.mha

 
I hope it helps! 

Cheers, 
Marc VILA


On Sat, 2013-11-09 at 20:52 +0800, WANG Mengjiao wrote:
> Hi, all.
> I am dealing with the fdk reconstruction of projections from a GE Innova 
> 4100IQ C-arm equipment. The rotational scan covered about 200 degree. 
> SID = 720. SDD = 1195.
> The detector is centered.
> For the first try, I used the rtkfdk.exe for reconstruction, it popped 
> up some output window. The program was still running, but never gave any 
> reconstructed result.
> For the second try, I changed the source code of rtkfdk.cxx by disabling 
> the displaced detector filter and short scan filter. This time the 
> program worked and gave me some
> reconstructed images. But the images are very lousy.
> Does anybody has clue for this situation?
> PS: The rotational projections, the geometry file, and the screen shot 
> of the reconstructed images can be downloaded by this link:
>          https://www.dropbox.com/sh/y5iyfjtcc9i49n0/AXso1Lvbg3
> Thanks in advance.
> MJ
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> Rtk-users at openrtk.org
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