Radiology = medical specialty = experts in the acquisition, interpretation, and significance of medical imaging = college + 4-year medical school + 1-year internship + 4-year residency. If that's what you want, then just worry about getting into medical school. Apart from concentrating on the physics of imaging, there's basically nothing you can do as an undergraduate student to prepare you for radiology apart from just getting into medical school.
Radiography = technical specialty = practical skill set concerning obtaining images using x-rays. One, two, and four year programs are available. Many technologists go on to become certified in CT, MRI, nuclear medicine, mammography, etc. This is a forum primarily for radiologists; try AuntMinnie.com if you want to learn more about radiography.
