It seems everyone who wants to do things online even the medical field subjects. It is not recommended or can it be done online especially the radiography field. You are better off learning this in a hospital based program, in a community college or a 4 year university because of the clinical and didactic portion of it. You are dealing with real and sick people and you can't always find answers off the book. It depends on the program you are in but universally, you need anatomy & phsiology 1 and 2, chemistry, physics and algebra but of course these classes can change. You definitely need to know your anatomy inside and out, but don't worry you'll get used to it. I deal with sick people everyday and everyone of them is different regardless the exam is based on their pathology, size, attitude, orientation, and culture. Most common exams you see are chest x rays (how lovely lol). Sometimes you get good or bad days like any other job but honestly it doesn't feel like a job depending how much you like it. I like what I do but I do want to do something else and there are opportunities in this field other than just doing x ray. It is also good to know more than one language even if it is based on in x ray only because you never know if you'll get a patient who doesn't speak one word of english. Hablas ingles? Good luck.
I am a full pledge x ray tech, radiological technologist, whatever. =)