Projections consisting of a single ray (listmode)

[BOle-ProZ]

Hello TIGRE community,

I have a question regarding the SIRT algorithm (or any other to solve my problem).
Usually, when talking about a projection from a certain angle, a 2D "look through" projection is meant. Is it also possible to reconstruct a volume from an arrangement of rays with known trajectories through the sample? Each ray is independant and has a brightness value associated to it. I added an image to illustrate this problem.

Please don't hesitate to ask for clarification if needed.

Thank You and have a nice Day!
Ole

[AnderBiguri]

Hi @BOle-ProZ ,

I see, you are asking if its possible to do listmode reconstruction, essentially, right? Is this for PET, possibly?

The answer is no, unfortunately. Listmode requires a different setup for the projectors, and a different geometry description (2 points per line of response etc). Unfortunately TIGRE does not have that implemented. Have a look at STIR, it certainly has that (and more PET features).

However, if you or anyone around you is willing to put the time, I would be happy to guide you on what exactly is needed to change in the operators to make the listmode compatible. This is quite a big tasks, of course.

[BOle-ProZ]

Hello @AnderBiguri ,

Thank you for the quick reply! It is not a typical CT problem. We use an optical setup with a laser to measure fluorescence and absorption in very small samples.

What is STIR? A different tool box for tomography?

[AnderBiguri]

Ah I see. STIR is a different tool, yes, but it is explicitly for PET reconstruction, so while it can forward project listmode data, I am not sure you can use with data that is not from PET. I mean, you might, but I suspect it will be quite hard, its not an easy tool to use at all.