Target delineation and treatment planning in breast conserving therapy

The increased utilization of computed tomography based treatment planning and intensity modulated radiation therapy for treatment of breast cancer has yielded many potential advantages. Yet, a complete understanding of at risk tissues and avoidance structures is necessary to appropriately utilize such a conformal treatment design. Designing a treatment that maximizes dose homogeneity to the whole breast while minimizing dose to the lung parenchyma, coronary vessels, and myocardium has the potential to improve long-term morbidity and cosmetic outcome. In this review we discuss the utilization of three dimensional treatment planning and intensity modulation for the treatment of breast cancer. We focus on the delineation of target and avoidance structures in the setting of breast conserving therapy and the techniques utilized to maximize the therapeutic ratio.