I got that from Dr. Walsh's book, IIRC. He (or one of his co-authors) wrote that SBRT can be delivered in more visits and smaller fractions to try to reduce side effects, but it's tricky because the Medicare fee schedule will cover only 5 sessions of SBRT.

If anyone thinks that sounds dubious, I can try to look up the refence and see if I'm remembering correctly.

In any case, I did have my 60 gy of SBRT to the prostate spread out over 20 fractions here in Ontario and still developed mild radiation cystitis (occasionally annoying) and proctitis (barely notice it except for a bit of tingling or "buzzing" after eating spicy food).

Personally, I don't mind the radiation spread: it means the radiation would have killed cancer cells near the prostate as well as those in it, giving me a much better chance (in my layperson's opinion) of long-term remission for my aggressive, stage 4b PCa. A bit of urinary-tract irritation seems like a very small price to pay.