Figure 2.

Mean lung dose (MLD) and lung V5 comparisons according to treatment modality and with regard to tumor locations. Dosimetric parameters for proton beam therapy (PBT) were statistically significantly improved as compared with other photon plans at each location. (A–C) Boxplots of the MLD are shown in units of absolute dose per location. (D) Boxplots of median differences in the MLD between photon-based radiotherapy techniques and PBT. (E–G) Boxplots of the percentage of the lung receiving 5 Gy in each subgroup. (H) Median differences in lung V5 between photon-based radiotherapies and PBT. ** p ≤ 0.01; *** p ≤ 0.001; **** p ≤ 0.0001.