Radiology, also called diagnostic imaging, is a series of different tests that take pictures or images of various parts of the body. Many of these tests are unique in that they allow doctors to see inside the body. A number of different imaging exams can be used to provide this view, including X-ray, MRI, ultrasound, CT scan and PET scan. Radiologists interpret a broad spectrum of diagnostic tests including x-rays, ultrasound, bone mineral densitometry, fluoroscopy, mammography, nuclear medicine, CT and MRI.