I found this post just now.

Yes, I did hyperbaric sessions in a six person chamber. Just before Covid, when it became a hazard to be close to six strangers. All the others were cancer patients of different tumor types. I'm given to understand that it is effective for radiation proctopathy (proctitis) , but that it can take excessive hours. I was there for the bleeding. Others were there to reduce swelling, some so that they could have retreatment. I did 20 hours. And I didn't experience a reduction of bleeding which can take 90 hours. I don't think that it always works for the bleeding, but I did notice reduction in inflammation in unrelated areas.
It was quite pleasant.

You probably mean hyperbaric oxygen therapy (HBOT).

It can be used for radiation-induced proctitis, cystitis, colitis, and enteritis. Which one(s) are you looking to resolve? I have information on each of them.

Radiation damage to the bladder

I had hyperbaric oxygen therapy (HBO is what it is shortened to in upstate NY) for radiation proctitis. It significantly reduced the bleeding I was experiencing and aided internal healing. Usually there were 3 to 5 others in the chamber with me. I would say 1/2 were prostate cancer patients who had had radiation, 1/6th were other cancer patients and the rest were patients who had toes removed due to diabetes / lifetime of smoking tobacco. It was a time commitment, 3 hours per session, 1 1/2 hours travel time, 5 days a week for 30 sessions.

Thanks, very helpful.