@northoftheborder (how is Canada these days)
Never heard of the photo (SBRT) causing the inability to ever take shirt off. But I am not as familiar with photon as I am with proton. Did the photon radiation subject your entire chest area to significant radiation?
It would make sense if it had because photon radiation burn on skin is like a bad repeated sun burn so could make it sensitive to sun burns. But why so much in chest area and not just around entry sites.
I had pencil beam proton. It is a very precise beam and depth of release radiation. My areas of skin tanning were on the top of each side of hips but only a couple of inches. I have a ICD/Pacemaker and UFHPTI physics department recommend the pencil beam proton for me to keep radiation away from my ICD/pacemaker.
You are right on proton. R/O expalined the intensity of proton radiation going in is very much lower than the intensity of the radiation at the programmed release depth.
My R/Os explained (like yours did) why they don't just radiate biopsied areas, or MRI areas, as take a chance of a cancer cells being missed in prostrate or in the margins ouside the prostrate.
I worry sometimes when I read radiation treatments directly targeting the MRI confirmed cancer areas only or biopsied confirmed cancer areas only. You would think this would increase the chances of missing cancer cells.
There's no visible skin damage, but the SBRT machine circles around delivering radiation to the same place from different angles and directions, so I have two sensitised areas: one around my middle chest (from the radiation to the metastasis/surgery site) and one around my lower abdomen/groun (from the radiation to my prostate).