After researching, as a layman, the many radiation treatments, it came down to Proton or the MRIdian radiotherapy. I also spoke with oncologists who have used both. My “feel” was that the MRIdian was a better fit for me as, in terms of protecting healthy tissue, if you can see it you have a better chance to treat it. it is a real time MRI attached to a radiation machine. Second, the machine automatically stops if the radiation goes outside the target mapping parameters. Third, the target map PLUS the margins they add to limit the radiation to protect healthy tissue is narrower with the MRIdian than proton so it supposedly reduces the amount of radiation hitting healthy tissue. I was also told to have spaceoar gel inserted which adds about 1/2 inch space between the rectum and the prostate.