Comparison of carbon-ion radiotherapy (RT) and X-ray RT dose distributions in Patient 1. (a) Dose distribution of the carbon-ion RT applied in Patient 1 for the lymph node (LN) recurrence. Carbon-ion RT of 48 Gy (RBE)/12 fractions/3 weeks was given to the left common iliac LN and the lower para-aortic LN region at the National Institute of Radiological Sciences, Chiba, Japan. The isodose lines are shown by percentage with respect to the total dose of 48 Gy (RBE). (b) Simulated dose distribution of X-ray (RT) using orthogonal 4 fields. The anterior-posterior field of the initial RT is shown with thick red lines. The 50% isodose lines are highlighted in green.