Radiology is the specialty of medicine that deals with the study and application of imaging technology to diagnose and treat diseases. Radiology uses imaging technologies, such as X-ray radiography, magnetic resonance imaging (MRI), nuclear medicine, ultrasound, computed tomography (CT), and positron emission tomography (PET) to see within the human body in order to diagnose disease and abnormalities. Radiology is a key part of clinical practice across a wide range of medical disciplines. Diagnostic radiology helps health care professionals see structures inside your body. Radiological procedures are medically prescribed and should only be conducted by appropriately trained and certified physicians under medically necessary circumstances. Radiologist physicians have four to six years of unique, specific, post–medical school training that includes radiation safety and ensure the optimal performance of radiological procedures and interpretation of medical images.