[Rtk-users] rtkadmmwavelets ring artifact

[Joel Beaudry]

Sure thing, thanks for the reply Simon. I've attached a Coronal and Axial
slice showing the ring. I'll wait for Cyril's reply.

The image quality is pretty poor but I'm using ~70 projections (4DCBCT), so
that's expected. Admittedly, I'm not using a high
number of iterations (n=10) but I suspect this ring artifact is from
something else. This does not occur when using rtkadmmtotalvariation, but
only the admmwavelets.

And just a general question regarding the nature of iterative
reconstructions. I'm currently using no input image, so I assume the
initial guess is just some uniform value but is it beneficial to first do a
full (so use all projections) FDK reconstruction and use that as the input
instead?

Thanks,
Joel

On Mon, Mar 16, 2015 at 1:27 AM, Simon Rit <simon.rit at creatis.insa-lyon.fr>
wrote:

> Hi,
> Could you provide a snapshot?
> Cyril, the developer of this method, is away for a few days but he'll
> be able to answer next weeks.
> Cheers,
> Simon
>
> On Fri, Mar 13, 2015 at 7:49 PM, Joel Beaudry <joelbeaudry at gmail.com>
> wrote:
> > Hi RTK users/developers,
> >
> > I've been using RTK for CBCT reconstructions and found it to be very
> useful,
> > so thanks for all the work done on it!
> >
> > As for my question,when I use rtkadmmwavelets I get a ring artifact in
> the
> > center of the image. I'm using it for 4DCBCT reconstructions, so I'm not
> > using the full number of projections and not sure if this is a
> contributing
> > factor. From reading previous posts I know that the entire object must
> be in
> > the reconstruction, and so I have included both the patient and couch in
> the
> > reconstruction volume but still get the ring artifact. Has anyone else
> > encountered this? Any ideas/suggestions?
> >
> > Cheers,
> > Joel
> >
> > PS. When trying rtkadmmtotalvariation I don't encounter such issues.
> >
> > _______________________________________________
> > Rtk-users mailing list
> > Rtk-users at public.kitware.com
> > http://public.kitware.com/mailman/listinfo/rtk-users
> >
>
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