[Rtk-users] Insufficient Data For Proper Parker Weighting

[Simon Rit]

Hi,
You are getting this because RTK detects that the scan is too short. Parker
weighting requires pi + the fan-angle to be able to reconstruct exactly the
central slice of your scan. Check here
<https://github.com/SimonRit/RTK/blob/master/include/rtkParkerShortScanImageFilter.hxx#L139>
how this is calculated in RTK.
Possible solutions are cropping the projections to reduce the fan angle.
I'm not sure what are the consequences but they'll probably be small since
not much is missing in your case. It's even likely that RTK could be
improved by discretizing differently the integral in parker weighting, in
which case you'd get enough projections.
Simon


On Mon, Jun 15, 2020 at 10:56 AM Brani Rusanov <Brani_Rusanov at hotmail.com>
wrote:

>
> Hi,
>
> I am attempting to reconstruct Varian raw cone-beam data. The specific
> type of scan is a short scan, 200 degrees generating 501 projections.
> During reconstruction I get the message: “you do not have enough data for
> proper Parker weighting (short scan) Delta is 9.951 degrees and should be
> more than half the beam angle I.e. 11.2359 degrees.”
>
> Since I have not generated the geometry myself, rather, used a pre-set
> Varian protocol, I am unsure why I get this error.
>
> How could I rectify this issue? Furthermore, what consequences are there
> to not applying a Parker weighting?
>
> The geometry header is attached.
>
> Your response is greatly appreciated,
> Brani
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