You need to clarify what it is that you want to do. If you want to be a rad technologist (choice A in f_w's response) and be involved with taking images, the people on this forum probably do not know a whole lot about the process.
If you want to be a radiologist (choice B in f_w's response) and be involved with interpreting images, the people on this forum will have much more advice to offer. Becoming a radiologist is a much longer road than becoming a rad tech. You must first get a bachelors degree from a 4 year university or college. Then, you must go to medical school which is difficult to get into. I would say that the 'average' medical student in the US has about a 3.5 GPA and 30 on the MCAT. Once you graduate from medical school (4 years), you have an MD and must go through 5 years of training called residency. At that point, you could call yourself a 'radiologist.'