A controlled area is the area outside of a restricted area but within the area whose access is limited by licensed operators. The access, occupancy, and working conditions are controlled for radiation protection purposes.
A controlled area includes the location of a radioactive waste disposal facility, identified by institutional control that is intended to be used for monitoring and surveillance of a disposal facility and to act against or restrict public access, and the subsurface underlying a surface location.

Radiation can ionize matter caused by the high energy which displaces electrons during interactions with atoms. In the electromagnetic spectrum higher frequency ultraviolet radiation begins to have enough energy to ionize matter.
Examples of ionizing radiation include alpha particles, beta particles, gamma rays, x-rays, neutrons, high-speed electrons, high-speed protons, and other particles capable of producing ions by direct or secondary processes in passage through tissues.
Damage of living tissue results from the transfer of energy to atoms and molecules in the cellular structure. Ionized cells have to repair themselves to remain alive. Generally, healthy cells have a higher capability to repair themselves than cancer cells.

Biological effects of ionizing radiation exposure:
Ionizing radiation are used in a wide range of facilities, including health care, research institutions, nuclear reactors and their support facilities, and other manufacturing settings. These radiation sources can pose a serious hazard to affected people and environment if not properly controlled.

See also Radiation Safety, Controlled Area, Radiotoxicity and As Low As Reasonably Achievable.

In a supervised area, working conditions are kept under review but special procedures to control exposure to ionizing radiation are not normally necessary.

See also Controlled Area.

(ROI) Keyboard controlled identification of a given area of an image for numerical analysis and the area of anatomy being scanned that is of particular importance in the image. This area can also be a volume, than called (VOI) volume of interest.
A ROI can be used for purposes such as calculation of pixel statistics. ROI measurements should be made with the smallest area and away from boarders and edges to avoid partial volume averaging.