Vp3: I have had experience with the Viewray Mridian Machine. I just completed my five treatments with it in February. The 2mm margins are tighter than other Radiation machines And the automatic gating gave me extra comfort. I had 10.2 psa and 3+4 Gleason. I narrowed my radiation choices down to Proton Therapy and the Mridian machine. I would make that same decision again. Side effects were some restriction of urine flow but I took flomax after 3 sessions and it helped. Happy to answer any questions.