Proton therapy: Why there are different numbers of treatments?

Kkp10: Generally, nccn.org, created by dr’s for dr’s and patients provides a full complement of radiation therapy recommendations. Radiation treatments from machine to machine are different. Part of that is the issue of the mm’s of margins used in the machine type that can have a HUGE impact on how much healthy tissue gets radiated and therefore quality of life.

I did 5 treatments with the MRIdian Viewray machine at Orlando health. They also have the proton therapy machine. After discussions with 5 radiation oncologists mostly from different institutions, I was able to choose the MRIdian. There is a reason that new technology gets offered and in this case it was because of reduced margins, automatic shutoff and one unit MRI/Radiation combo.
Spaceoar made sense to me but the urinary issues were more vulnerable with wider radiation margins so again, the narrower margins made a difference for me.
Cornell Weill/Colombian Presbyterian in NYC is doing a one treatment clinical study vs the 5 treatments with the MRIdian. Generally, I found that the radiation oncologists did not really discuss the differences in one machine versus another even when they owned more than one type of radiation machine. The fallback seemed to be the outcomes were the same without really talking about the subtleties related to quality of life.

FYI, Mayo Rochester has the Hitachi Proton Beam System. News Release can be seen here:
https://www.hitachi.us/press/09152015
Siemens makes a system as well.

Amazing kit and we are lucky to experience our PC while this technology is available.

Best wishes for a successful outcome with minimal side effects.