A Radiation Therapy Contouring Atlas for Cardiac Conduction Node Delineation.

PURPOSE: The heart is a complex organ at risk. Currently, radiation therapy cardiac delineation atlases do not include conduction system substructures, which exposure may clinically translate into arrhythmia and conduction disorders. We present a method to reproducibly delineate conduction nodes on noncontrast simulation computed tomography scans. METHODS AND MATERIALS: Localization and dimensioning of the sinoatrial and atrioventricular nodes volumes on noncontrast simulation computed tomography scans were proposed based on radio-anatomic and histologic considerations and agreed upon by a multidisciplinary staff. RESULTS: The proposed atlas enables the dosimetric evaluation of the sinoatrial and atrioventricular nodes exposure, and both contours correspond to 2-cm diameter spheres. CONCLUSIONS: This delineation atlas should facilitate the delineation of cardiac conduction nodes in clinical research and daily practice.