Heart and coronary artery protection in patients with mediastinal Hodgkin lymphoma treated with intensity-modulated radiotherapy: dose constraints to virtual volumes or to organs at risk?

Background and Purpose: To increase heart and coronary artery protection in patients with mediastinal Hodgkin lymphoma treated with intensity-modulated radiotherapy (IMRT).
Materials and Methods: Twenty patients with early-stage mediastinal Hodgkin lymphoma entered the study. IMRT was delivered to the initially involved lymph node volumes. Various virtual volumes (VVs) were designed to improve the protection of the heart and the origin of the coronary arteries, which were the organs at risk (OARs), while preserving adequate PTV coverage. The results obtained with VVs were then compared with those obtained with dose constraints assigned to OARs.
Results: The most satisfactory VV was obtained using the PTV expansion concept. The best compromise between adequate PTV coverage and OAR protection was obtained with dose constraints assigned to the PTV expansion VV and to the origin of the coronary arteries.
Conclusions: IMRT can be improved by using dose constraints assigned to the PTV expansion VV and/or to the origin of the coronary arteries.