Ive done wayyyy more sets of dives than I ever wanted to do. In my situations where I did HBO it was to help with major healing problems after rads.
For me it worked great with healing wounds when I had already been thru dozens of other medical treatments that failed, even after working for months with wound care specialists. This is a very different situation than what your doc suggested to you!!!

Unfortunately, OC patients post rads have a very long road until they can consider themselves completely recovered. Most patients will notice slow or small improvements here and there in their sense of taste and saliva production. Since you are only 10 months post rads, you still have a long way to go until you would be considered completely healed from rads. Most OC patients have been thru substantial side effects when doing rads for OC, when adding chemo its even more complications and side effects. It takes a full 2 years before someone going thru rads for OC is fully recovered. Even then we have had some members report improvements in their remaining medical issues up to 4 months past the 2 year point. A full recovery always seems to take forever and will never happen quickly enough for any of us.

Even though I do not have a medical degree, years of schooling or a background working in the medical field, I am VERY familiar with HBO and everything it entails. Im a bit surprised this was offered to you at all when you're only 10 months post rads. This isnt usually offered for fixing the saliva rads destroyed, at least this hasnt been mentioned by anyone as an option. More often pilocarpine is offered after about a year and half or 2 years post rads. Its a medicine to promote blood vessel rejuvenation but it also has a side effect in some patients with increasing how much they sweat. I tried it and found I was sweating so much it was NOT something I wanted to continue, others havent experienced that side effect and found it helps. Gum or lozenges with Xylitol and sour things will also help with making more saliva.

Hang in there, hopefully in time your saliva production improves. For me at 10-12 months post rads I was still always carrying a water bottle everywhere I went but the longer I was post rads, the less dependent I became on needing to always have it with me.