Fig. 1

The simulated dose distribution of three radiation techniques for esophageal carcinoma. (A) Intensity modulated carbon-ion radiotherapy, IMCT, (B) Intensity modulated proton radiotherapy, IMPT, and (C) Photon intensity-modulated radiotherapy, IMRT. The isodose of 65.84 Gy was 95% of the prescription dose, and is presented together with levels 60, 50, 40, and 30 Gy. Doses are presented as the RBE (relative biological effectiveness)-weighted dose