Hello, to become a radiologist it will take 4 years at University Medical School followed by 2 years as an assistant in a Hospital, so 6 years in total, after this you can become a consultant after a further 4 or 5 years depending on which Hospital you work in, the standard is generally the same worldwide...
Radiologists are a shortage skill worldwide and very sought after.
You can contact General Electric and Siemens Medical and also Phillips medical in the USA and ask for information on MRI, CT Scanners and Ultrasound equipment as well as mentoring from some of their radiology specialists, they will keep you right and may even direct you towards a scholarship or sponsorship.
A radiologist is a medical doctor, so the same amount of schooling a medical doctor needs is what you will have to complete to be a radiologist. Here in the US, this means 4 years of university or collage, then completing 4 years of medical school, then a radiology (also known a diagnostic imaging) residency, which is often about 4 years as well.
Grant is right! There is a world wide demand for radiologist, and this can be a very lucrative and rewarding career.
There are also other careers related to diagnostic imaging that do not require you to be a doctor. You can be an ultrasound technologist, or a CT and MRI technologist. These are people who perform the scan and exams that generate the radiographs ("x-rays") and CT/MRI/ultrasound images then get interpreted by a radiologist. Diagnostic imaging technologist often need only 2-4 years of schooling/training beyond high school.