[Rtk-users] bright circle on the reconstructed image

[Howard]

Hi,

I use rtkfdk to reconstruct varian cbct images following the example on rtk
wiki page. The projections were obtained with half fan mode because it is
an abdominal region with the patient lateral x AP dimension of 550x550. The
reconstructed cbct images have a big bright circle around
the image. Please see the image:
http://expirebox.com/download/2f55c9d8f0bc83138b954d2fec08e78c.html

I am using Ubuntu Linux box to reconstruct. Two sequential commands were
used:

./rtkvarianobigeometry --xml_file ProjectionInfo.xml --path Scan0/ --regexp
Proj_.*.hnd -o varianGeometry
and

rtkfdk \
   --geometry varianGeometry \
   --regexp .*.hnd \
   --path ../Scan0 \
   --output rec.mha \
   --verbose \
   --spacing 2.0,2.0,2.0 \
   --dimension 256,100,256 \
The projections are stored in the standard varian format: Scan0 and
ProjectionInfo.xml with 644 projection images.  I assume that rtkfdk
handled the half fan geometry properly. What did I do wrong then?  Many
thanks!

-howard
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