Carbon ion radiotherapy in NIRS/HIMAC

Purpose: Carbon ions show an increase in energy deposition with penetration depth up to a sharp maximum at the end of their range to form the Bragg peak. The particle range is determined by the energy of the incoming particles. Favorable dose distributions with a steep dose fall-off at the field borders and more precise dose localization can be achieved with this beam compared with photon beams. As a consequence, it seems likely that carbon ion radiotherapy can be performed without aggravating toxicity in surrounding normal tissues. Carbon ions have a biologic advantage which can be quantified as high linear energy transfer (LET). Their biologic efficiency increases at the end of the beam’s range, whereas it is low along the entrance channel. When different clinical situations are considered, the biologic advantages of carbon ions are expected to be most pronounced for tumors that demonstrate low radiosensitivity when treated with photons. This is particularly true when the tumor is surrounded by radiosensitive normal tissue. This paper described the results of phase II clinical trials and preliminary results of Phase I/II dose escalation study of carbon ion radiotherapy. Materials and methods: Between June 1994 and August 2007, a total of 3,452 patients wer