Need an MBBS. So you need to be hitting the 99s and smash the UMAT. Finish your med degree, do your internship, complete your 2 year residency and then be accepted into the Royal Australian and New Zealand College of Radiologists to undertake training as a radiologists as a registrar then following that (4-7 years registrar training, not sure) you complete your fellowship
I made that sound easy, well it's not, it's extremely difficult. Also, I'm not sure if what I said was 100% correct, I'm just going off the top of my head as I have no intentions of going to med school so I haven't researched this extensively.
I am sure if Dr_Fresh sees this he'll be able to answer it better.