Comparing Proton Beam to Intensity Modulated Radiation Therapy Planning in Esophageal Cancer

Abstract Purpose: To compare passive-scatter proton beam therapy (PBT) versus intensity-modulated radiation therapy (IMRT) for reducing heart/lung dose in esophageal cancer, and to identify anatomy and treatment planning parameters that can lead to suboptimal proton plans. Patients and Methods: Passive-scatter PBT versus IMRT mean doses and coverage to the lung/heart were evaluated for 55 patients with esophageal cancer from 2007 to 2010. Geometric relationships between the tumor (distance from planning target volume to carina, and percentage of uninvolved heart) and doses to the lung/heart, respectively, were used to predict expected doses to these normal tissues. Cross-comparisons of heart versus lung dose and proton versus photon mean lung/heart dose were used to identify suboptimal proton dosimetry. Results: Dose–volumetric analysis showed that, for the lung and heart, although protons resulted in smaller volumes receiving lower doses (5–30 Gy), photons achieved smaller volumes receiving higher doses ...