Maybe radiologist mean something different in my country, but here radiologist don't diagnose (i mean, except you see them for a broken bone or something), oncologist do. I did an observation internship with a radiologist when i was 20 (95% of my family are doctor/nurses/PT, i wanted to know what a degree in physics could help me do in the field, and radiologist was the only path to medecine from my initial formation where i only lost a year, and not two). You spend your time calculating doses, finding patient history, and calibrating machines, it's much more a technician role than a MD. In any case, and even if in the US radiologist diagnose cancer, that's such a small part of their job it shouldn't matter.