A Radiation Therapy Contouring Atlas for Cardiac Conduction Node Delineation

Area of Science:

• Radiology
• Cardiac Electrophysiology
• Radiation Oncology

Background:

• Radiation therapy for thoracic malignancies poses risks to cardiac structures.
• Current cardiac atlases lack delineation of the sinoatrial (SA) and atrioventricular (AV) nodes.
• Exposure of these nodes can lead to arrhythmias and conduction disorders.

Purpose of the Study:

• To develop a reproducible method for delineating cardiac conduction nodes (SA and AV nodes) on noncontrast simulation computed tomography (CT) scans.
• To create an atlas for radiation therapy planning that includes these critical substructures.

Main Methods:

• Utilized radio-anatomic and histologic data for node localization and dimensioning.
• Defined SA and AV node volumes on noncontrast simulation CT scans.
• Achieved consensus on delineation through a multidisciplinary staff review.

Main Results:

• A novel delineation atlas for cardiac conduction nodes was established.
• The atlas facilitates dosimetric evaluation of SA and AV node radiation exposure.
• The delineated contours for both nodes are represented as 2-cm diameter spheres.

Conclusions:

• The developed delineation atlas aids in accurately outlining cardiac conduction nodes.
• This atlas is expected to improve clinical research and daily practice in radiation oncology.
• Facilitates precise assessment of radiation dose to the SA and AV nodes, potentially reducing cardiac complications.