Fig 2.
(A) Box plot of mean radiation doses to the lung, esophagus, and heart. Mean doses to the lung and esophagus were no different between the two treatment groups (intensity-modulated [photon] radiation therapy [IMRT] and passive scattering proton therapy [PSPT]), but the mean heart dose was lower for those treated with protons (P = .002). Whiskers indicate 1.5 times the interquartile range above and below the mean; dots represent outliers. (B) Box plot of distributions of dose-volume indices for the lung and heart. PSPT led to smaller volumes of lung being exposed to low volume doses (V5-10) and larger volumes of lung exposed to ≥ 20 Gy (relative biologic effectiveness [RBE]). PSPT reduced the volume of heart exposed to all dose levels measured (5 to 80 Gy [RBE]). Whiskers indicate 1.5 times the interquartile range above and below the mean; dots represent outliers.