Organ at Risk
Pronunciation: O-A-R
Also written as: OAR — Organ at Risk
Normal tissue structure requiring dose limitation during radiation therapy planning to prevent complications.
Full Definition
Organs at Risk represent normal tissue structures that may suffer significant morbidity from radiation exposure during cancer treatment, requiring specific dose constraints during treatment planning. OAR identification and contouring is a critical step in radiation therapy planning, with established dose-volume constraints based on clinical data and normal tissue complication probability models. Common OARs include the spinal cord, brainstem, heart, lungs, kidneys, and eyes, each with specific tolerance doses that must be respected to minimize treatment-related complications.
Usage
Usage note: Always specify dose constraints for each OAR in treatment planning documentation.
In Context
- "All organs at risk met institutional dose constraints in the final treatment plan." — Treatment planning summary
- "The spinal cord, designated as the primary OAR, received a maximum dose of 45 Gy." — Dose-volume analysis