Brief Report of a New Anatomical Region at Risk in Thoracic Radiotherapy: From Discovery to Implementation

Increasing radiotherapy dose to select cardiac structures is associated with cardiac events and premature death. Previous studies have found a dose-response relationship for structures at the base of the heart. We have defined a new cardiac anatomical region at risk for radiotherapy by consensus opinion, based on image-based data-mining studies. The cardiac avoidance area comprises the superior vena cava, right atrium, aortic root, left main coronary artery, and proximal segments of the left anterior descending and right coronary arteries. We describe a contouring atlas for the cardiac avoidance area to facilitate implementation.