I assume that this is an honest question and that you are not in the medical sector:
- interpret medical imaging studies including x-rays, CT scans, MRI, Ultrasound and nuclear medicine exams. Typically, this interpretation is provided in the format of a written report to the medical practitioner who requested the exam.
- supervise the acquisition of imaging studies
- consult for their clinical colleagues on imaging related issues
- perform image guided procedures
The training to become a radiologist involves graduating from medical school, going through a general medical internship and 4-5 years of radiology residency.