Kim:
That's a great question for which there is no straightforward answer. I'm going to ask for some more details on your part and give you some ideas on my part. First, are you sure that the area of bone in question is within the radiation field? You will have to ask that question to your radiation oncology department. It would also help me to know what kind of cancer this is ... I'm going to guess a sarcoma just based on the location you have described.
Are you absolutely sure that the bone disorder is related to the radiation? (From a Medicare perspective, that link is imperative.) If so, you could make a case for osteonecrosis of the femoral head. If I had this patient (and more clinical details would help), I would make the history as involved as I could to support that diagnosis. Your physician must document a history of cancer, the area of the body treated by radiation, the location of the radiation field, the total dose of radiation in the area that the MRI shows injury, the proximity of the bone in question to the radiation field, the type of injury now occurring, and the potential surgical intervention, if needed.
So, it would help to know that the bone has a visible pathologic fracture or what distinct radiographic changes that the radiologist interprets as osteoradionecrosis. (I'm pressing on this diagnosis to be certain that the radiologist didn't say aseptic osteonecrosis of the femoral head ... That would be a totally different subject.)
In summary, this is complicated. I don't think I've ever seen osteoradionecrosis of the hip. Primarily, we look at ORN of the mandible as significant b/c there is only one artery supplying blood to the mandible. That is not the case in the hip. More pertinent information, if you can share it, might change my mind, but I would approach this very carefully. You would be in the Medicare cross-hairs for continual audits, and as far as I know, has not been described in the literature where HBOT has been used. It would be much easier is there was a demonstrable soft tissue injury as well. That makes a good history of STRN.
PS: I did a PubMed search ... the only paper was a pediatric paper dealing with marrow edema and aseptic osteonecrosis of the femoral head.