@anon271488: I don't know about other countries, but in the United States, you'll need four years of basic medical school beyond your undergraduate degree. While in medical school, you'll take some basic, core courses, and then, depending on the school where you attend, you'll start taking classes specific to your field of practice, like radiology. During your residency and fellowship period, you'll go further into your specialty, where you'll basically be practicing under the supervision of a fully qualified doctor.
The exact names of the classes vary by school, as do the books, since most professors choose their own particular, preferred textbooks, and students purchase these from the university bookstore, or from another student, or at an off-campus bookstore.
What you really need to do is to contact the particular medical schools that interest you and ask for a copy of their current catalog, or go to their websites and look at their online catalogs, which outline the course curriculum for various degrees and specialties. You'll also need to apply for acceptance into a medical school to begin your training. And you have to go to medical school to get licensed in radiology and to even be approved to take the licensing exams.