I'm sorry did you just call Medical Physics a 2 year "delay" that barely touches the field? All of my work in grad school has been in radiation oncology. I used linear accelerators, stereotactic surgery machines such as the Cyberknife, and did a TON of treatment planning using Theraplan Plus, Xio, and Eclipse treatment planning systems. I studied two quarters of internal dosimetry and nuclear medicine. I also did research in radiation biology to assess various fractionation regimens on yeast cells. In addition to this I worked part time as the treatment planning physicist for veterinary radiation oncology at UCLA. I've cranked out over a hundred different plans for dogs and cats on Theraplan using a Co-60 machine. Humans have IMRT and IGRT and various energies including proton, electron, and the less popular neutron therapy. Cobalt 60 is pretty bread and butter dosimetry but the principles of treatment are the same as with humans.
I absolutely busted my ass and got to know the ucla rad onc faculty and resident faculty very well. I am very interested in rad onc and even the residency director at ucla's rad onc told me flat out that learning physics is probably the most important aspect of radiation oncology. (He himself is a Phd in medical physics). No doubt, research in rad onc during med school will help, but I have a hard time believing that any research I partake in during med school will give me a greater exposure to rad onc than my graduate school experience.