Radiology: the science that uses medical imaging to diagnose and sometimes also treat diseases within the body. A variety of imaging techniques such as X-ray radiography, ultrasound, computed tomography (CT), nuclear medicine including positron emission tomography (PET), and magnetic resonance imaging (MRI) are used to diagnose and/or treat diseases. Medical images are stored digitally in the picture archiving and communication system (PACS) where they can be viewed by all members of the healthcare team within the same health system and compared later on with future imaging exams.