Biological effects of radioactive 9C-ion beams on cells

The distinguishing feature and current technique progress of tumor treatment with heavy-ion beams is introduced in the paper. Additional superiority to tumor treatment from a radioactive ion beam (RIB) is emphatically discussed. The experimental research of the radioactive ⁹C-ion beams aimed at tumor treatment at Heavy Ion Medical Accelerator in Chiba (HIMAC), National Institute of Radiological Sciences (NIRS), Japan is described in detail, including production of the beams, optimization of parameters, distribution of depth dose, survival effect of cell and comparison of RBE between ⁹C- and ¹²C-beams. Results show that under 40 mm thick Beryllium target and 10 mm thick aluminum degrader at full (5%) momentum acceptance, the production rate and purity of the produced ⁹C-beams are 9.07×l0⁶ and 82.88% respectively with the primary ¹²Cbeams of 430 MeV/u and 1.8×l0⁹ pps. A uniform irradiation field with homogeneity up to 89.6% inside central area 10 mm in diameter is obtained by using spot scanning. In this case, the dose rate at the entrance is 0.5 Gy/h. In survival experiment of cells, the average relative biological effectiveness (RBE) of ⁹C-beams is 5.28 and 2.93 for ¹²C-beams in the region around Bragg peak. The RBE of ⁹C-beams is 1.8 times higher than that of ¹²C-beams. It indicates that cell-killing efficiency of ⁹C-beams is stronger than that of {u12}C-beams. ⁹C-beams are more efficacious for tumor treatment than ¹²C-beams.