Radiology is the medical specialty that uses special kinds of pictures to look at different parts of your body. Doctors use these pictures to look at your bones, organs, and tissues to figure out what might be causing any health problems you have. The kinds of pictures doctors can use are called X-rays, MRI scans, ultrasound, and CT scans. When doctors use X-rays, a small amount of radiation is sent through your body, and the X-ray machine takes a picture of what's inside you. With MRI scans, doctors use magnets to take pictures of how your organs are working, and with an ultrasound, doctors use sound waves to see what's inside of you. A CT scan lets doctors see a 3-D picture of your organs.