Question about analytical reconstruction for helical cone-beam CT

[zezisme]

Dear OMEGA developers,

thank you very much for developing and maintaining the OMEGA reconstruction framework.

I would like to ask a specific question regarding analytical (non-iterative) reconstruction support for helical cone-beam CT:

• Does OMEGA currently support analytical or approximate analytical reconstruction for helical (spiral) flat-panel cone-beam CT,
  such as helical FDK-type methods, rebinning-based FDK, or other approximate analytic approaches?
• Or is the current cone-beam support limited to circular trajectories, with helical geometries handled only via iterative reconstruction?

My interest is specifically in FBP/FDK-like analytical reconstruction, not iterative algorithms (e.g., SART, TV-based, etc.).

If helical analytical reconstruction is not currently supported, I would also appreciate knowing:

• whether there are plans to support it in the future, or
• whether the recommended workflow would be to perform helical-to-circular rebinning externally and then use OMEGA’s FDK implementation.

Thank you very much for your time and for making OMEGA available to the community.

Best regards

[villekf]

Hi zezisme,

Thanks for you interest towards OMEGA. Here are my answers:

1. No. There's no analytical reconstruction support for helical CT.
2. Yes, though technically the FDK reconstruction should also work with helical data, but the results are probably suboptimal.
3. There are some plans for better analytical reconstruction methods, yes, but not for the near-future so I don't recommend waiting for it.
4. Rebinning would probably be the best way to go if you must use FDK.

Just out of curiosity, is there a particular reason why you don't want to use iterative methods?