@erbill
I had 5 treatments with the Mridian MRI linac radiation machine but these days the Elekta Unity, with similar real time MRI features, is also available. Although Cyberknife, as I understand it, uses multiple beams automatically coordinated to radiate a small spot, I narrowed my choice down to Proton or Viewray's Mridian. I then spoke with 5 radiation oncologists trained or at centers of excellence, with direct experience with the machine, as well as the President of Viewray, at the time, for some additional insight. My goal was obviously, minimize the chance of a biological re-occurrence but also to reduce or eliminate side effects and toxicity for a better quality of life.

The dynamic adaptive capability was an important piece for me after the built in MRI which uses smaller margins (2 mm vs 3-5 for other forms of radiation) and the auto gating shutoff feature. Even though the prostate does not move as much as other organs, I wanted those capabilities as I knew the prostate could move because of bladder filling, rectal gas, or patient movement so I wanted it as part of the machine, just in case.

The bottom line for me was the built in MRI and smaller margins of 2 mm and full use of the machines functionality was best for my treatment.

The first link below is to an article from urology times talking about the Mirage randomized trial and its conclusion that there is a significant difference in toxicity and side effects between built in MRI vs fused CT or other images use. The second link is to another study showing support for the Mirage trial but over a two year period after the Mirage trial.
https://www.urologytimes.com/view/mirage-trial-margin-reduction-with-mri-guided-sbrt-reduces-toxicity-vs-ct-guided-sbrt
https://www.europeanurology.com/article/S0302-2838(24)02688-5/fulltext