That trial never made sense to me, unless you understand where Zelefsky is coming from. He started as a brachy doc and later became convinced that SBRT works as well (for monotherapy). So his first inclination is usually brachy, and he considers SBRT an add-on. Some SBRT docs (like Alan Katz) would argue that it provides as good or better dose to the prostate as any brachy dose could, so there is no need to add anything to it. Still others are giving IMRT with an SBRT boost to the prostate. I don't know that any are better than any of the others. SBRT monotherapy is certainly the most convenient of the alternatives, but there is very little data behind it so far.
To my knowledge,
many ROs use MRIs in planning for external beam radiation. They actually fuse the images of a CT scan and an MRI together. There is nothing unique either about
the equipment they use at MSK. There are 3 major manufacturers - Varian, Accuray & Elekta - and they all make excellent linacs. I think VMAT (arc) or Tomotherapy (spiral) gives excellent dosimetry for IMRT. The image guidance system they use is also important. More important than the machine is the experience and care taken by the RO in putting together the best plan possible. If you have someone local who has experience on some top-of-the-line equipment, it may be a lot more convenient than 20 trips into the city. Urinary urgency can be a problem on a long ride.
As for the spacer, I'm not really a fan. It "solves" a problem that isn't there. It does nothing to improve acute rectal toxicity, and late term rectal toxicity with modern IGRT/IMRT is very low anyway. It doesn't seem to be worth the cost, based on what I've seen so far.
https://pcnrv.blogspot.com/2016/08/spaceoar-hydrogel-decreases-rectal.html