Proton therapy for hepatocellular carcinoma: Current knowledges and future perspectives

Figure 1 Radiation dose distribution according to technique of radiation therapy. Axial views of A: 3-dimentional conformal radiation therapy (3D-CRT); B: Volumetric arc therapy (VMAT); C: Passive scattering proton beam therapy (PBT); D: Pencil beam scanning PBT; sagittal views of E: 3D-CRT; F: VMAT; G: PBT with wobbling technique; H: PBT with pencil beam scanning technique. There are low dose distributions in 3D-CRT (A, E) and VMAT (B, F) due to the exit dose.