Isolated power system? You need to define "critical care"!
ICU? NICU? Dialysis? Wet areas?
Be aware that you can achieve isolation "locally" by using services pendents. But such "solutions" are never cheap.
There is no general rule (as far as I am aware), but isolated power supplies are often found in operating theatres in some countries (where Local Codes may prescribe their use). There are pros, and there are cons.
Isolated power outlet for a (mobile?) x-ray unit? Unlikely, I would have thought. More likely to be a normally earthed outlet (but rated at 30 Amps or so) in an area otherwise provided with isolated outputs.
Again, Local Codes may apply ... but in reality you need to look at what the x-ray machine actually needs (that is, modern mobiles generally don't need anything other than a standard outlet - as found in the corridor)!
And don't forget that some areas (equipment) really need UPS (lab analyzers being a good - but often overlooked - example).
The bottom line with hospital mains power outlets is that you need to consider (study) the thing in the round, as it were. That is, a consistent approach applied throughout the hospital.
