This is something that surpised me- that medical physicists are ABR diplomates. To my knowledge, they are the only PhDs licensed by a medical specialty board. It also IMHO goes a long way towards explaining the collegial relationships I've observed in most places. I will say this, at most institutions I've visited, the medical physics guys are pretty cool, and attendings seem to really respect their opinions.
Medical physics is an applied physics degree. There is a little radiobiology, and some anatomy, but not tons. Therefore, medical physicists are not physicians. They never see the patient, and don't worry about types of cancer, or staging or adjuvant treatment, but are experts on stuff like beam fluence, tissue dose deposition, and linac QA. The best description of the raltionship between the two fields was this " To a radiation oncologist, radiation happens to be a tool to kill cancer. Medical physicists are people who see cancer as what happens to be in the way of radiation."
Consequently, each side kind of knows their area of expertise. No Rad Onc doc is going to sweat physics as long as the tissue dose objectives are reached. That is to say, no rad onc doc will get mad if their beam weighting is improved as long as the relevent tissues get the prescribed doses.
I will say this though: there is a vast difference in how interactive physics/physicians are at different places. At one place here it is very collaborative; at a local private practice I visited, it was like the plans went of to a different room, and magically reappeared after a couple days.
Finally, forget about the physics guys,how does a med student get get invited to a country club?