Half-Fan Scans of Varian CBCT

[world2005]

I would like to know if TIGRE can reconstruct Varian CBCT using a half-fan scan. I tried to use "d21_ScannerDataLoader.m" but could not obtain the image with full FOV on a thorax site.

Since TIGRE can read the Varian half-fan raw CBCT data, could I use any functions in TIGRE to obtain a full FOV projection from half-fan projection data?

Thank you very much!

[AnderBiguri]

hi @world2005 ,

I don't know! :) I have never tried the Varian Data loader much myself, but in theory calling VarianDataLoader() and then just doing a recon with FDK() should do the job. Does it not? What do you mean you could not obtain an image?
But yes, once read, you could use any other recon algorithm, not just FDK.

[world2005]

Hi @AnderBiguri ,

I apologize for the late response, which was due to intensive clinical work. I got the following warning because of a large detector offset by the half-fan thorax scan.

"Warning: Wang weights: Detector offset percent: 40.27 is greater than 30 which may result in image artifacts,
consider rebinning 360 degree projections to 180 degrees "

The reconstructed image quality is poor due to artifacts. Is it possible to rebinning 360 degree projections to 180 degrees using TIGRE? Could you please provide some suggestions?

Thank you very much!

[AnderBiguri]

Hi @world2005 ,

How does the reconstruction look like? Does it have a big circle in the middle of the recon?
Generally the wang weights do indeed not work super well if your detector offset is larger than 30% of the size of the detector. I know some people manage to get around this, but I am not sure how.

However note that if you use iterative recon, this should not be aproblem, Wang weights are a uniquely FDK issue, the rest of the algorithms should work.