The process of producing of an image by radiation other than visible light, originally used to describe the specific film based technique of producing an image of the internal structures of the body by the passage of X-rays or gamma rays through the body (and also known as roentgenography) but currently also includes the use of more technologies such as ultrasound as well as the CT or MRI scan. All of which are used by the medical profession as diagnostic aids.

Can also be used to refer to the practice of therapeutic radiography, which refers to the use of radioactive sources in medical, generally anti-cancer treatments, also known as radiotherapy.