Axial, coronal, and sagittal images of photon-based stereotactic body radiation therapy (SBRT) plans (left) and proton-based SBRT plans (right), both delivering 50 Gy in 4 fractions. A, colorwash of the photon SBRT plan shows the volume of the chest wall receiving 30 Gy in green. B, colorwash of the same CT data set used to plan for proton SBRT shows that significantly less chest wall receives 30 Gy.