[Rtk-users] Parker weighting

Simon Rit simon.rit at creatis.insa-lyon.fr
Tue Dec 8 07:56:56 CET 2015


Dear Shiras,
Yes, for practical reasons the first and the last projections are set to 
0 and the arc used in the Parker weighting starts between the first two 
projections and ends between the lasts two projections. There is a 
simple solution: add a projection at the beginning and the end of the 
arc, which can contain any pixel values but should be set where you want 
this arc to start. In the future, I think someone should once take the 
time to correct this but I haven't so far. I'll keep you posted on the 
mailing list when it's corrected.
Simon

On 07/12/2015 12:04, Shiras Abdurahman wrote:
> Hi all,
>
> I am trying to reconstruct a volume from projection data generated 
> with C-arm CT. There are 248 projections with an angular range of 199 
> degree. Technically, parker weighting should run without any problems. 
> However, I am getting an output message that "You do not have enough 
> data for proper parker weighting". After parker weighting, the two 
> extreme projections (projection number 1 and 248) were completely zero 
> and thus reconstructed volume contained artifacts. When I increased 
> the angular range, this problem did not happen. How can I solve this 
> problem without increasing angular range? Is there any threshold 
> constant that I can change in command line  or in my code?
>
> I really appreciate any help you can provide.
>
> With regards,
> Shiras
>
>
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