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 are9.07×10^-6 and 82.88% respectively with the primary ^12C-beams of 430 MeV/u and 1.8×10^9 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 ^12C-beams. ^9C-beams are more efficacious for tumor treatment than ^12C-beams.