@gsd I have reviewed the diffferent machines , with my Oncologist , using MRI and CT Guided technologies .
Clearly the MRI is the way to go , and insist on a rectum spacer . Many Oncologists insist they are not required . I err on the consertative side . The MR Linac guided ultra -Hypofractionated model machine is less available than the CyberKnife Machine . However " BOTH " can perform 2mm margin results .