Rad oncs have a great deal of patient contact with a lot of high tech radiology and physics as well. I rotated in this for a month in 4th year.
Basically, most rad oncs spend about 2/3 of their time in clinic. They see mostly cancer patients (breast, prostrate, advanced cervical, pancreatic, testicular, bone marrow ablation for leukemias, and others) who were referred to them by a surgeon or heme/onc doc. They do a initial H&P on these patients, determine if radiation therapy will be beneficial (usually the answer is yes). They then set up the patient for a simulation in a specialized x-ray machine and usually get planning CT for everything but breast CA. Using this info they plan out radiation windows and dosages to maximize the amount of radiatin going to the tumor while minimizing dose to other tissues.
The patient will then start a course of radiation lasting anywhere from 2 weeks to 30 weeks. Rad therapists give the radiation and the rad onc doc will usually see the patient in clinic once a week to make sure everything is going ok (there are lots of possible side effects). Once rad treatment is over, they will follow up with the patient for up to 5 years.
The lifestyle is great in that the call is usually not too bad (few rad emergencies such as Cauda Equina syndrome due to tumor). Generally the patients Onclogist or surgeon deals with hospitalizations and emergencies. Basically it is regular 8-5 days. The pay is great, over 200K on average.
Recently they are doing more procedures to give brachytherapy (radiation source inserted directly into or next to tumor) to cervical CA, prostate CA, breast CA. Brachytherapy of cardiac stents is also assisted by rad oncs (they just run the radiation part, not the cath). They can also do the new gamma knife radiation tx of brain tumors (not really a knife, more of a focusing of 100s of radiation beams).
Its a great field with a lot of rewards but also a lot of very sick patients for whom radiation is the last hope of a few extra months. You have to be able to deal with the fact that many of your patients will die. It is also a very research oriented field with new studies coming out all the time.
Competition for spots is very fierce with research and personal contacts being a key factor in this very small field. I'm surprised to see so many IMGs at the program you mention, but I am sure there is something in their history that sets them above the rest. I would have considered this field if I had known more about it prior to my senior year. If interested, try tagging along or doing a rotation to get more of a feel.