Mwarsha: I am not sure where you are located but here is a link to the viewRay website that gives locations of the machines in the United States.
https://viewray.com/mridian-treatment-centers/
Where I ended up being treated in Orlando, they had both the proton machine and the Mridian viewray linac radiation machine.

Many doctors will say that the outcomes for different machines are basically the same with some differences in the toxicity levels. It is difficult to get a doctor to talk about the subtleties of each individual machine and the side effects/quality of life issues in detail that you may experience from one machine to another. Obviously you can’t always predict everything But as I said before I made my decision based on what I thought would have the greatest chance of protecting my healthy tissue. To me that included multiple factors that the Mridian machine had that others did not. Feel free to contact me with any additional questions.