1. Enhanced efficiency in cell killing at the penetration depths around the Bragg peak of a radioactive 9C-ion beam
- Author
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Takehiro Tomitani, Shinji Sato, Mitsuo Yoshimoto, Tatsuaki Kanai, Yoshiya Furusawa, Mitsutaka Kanazawa, Atsushi Kitagawa, Qiang Li, Zengquan Wei, Mizuho Aoki, and E. Urakabe
- Subjects
Cancer Research ,Radiation ,Ion beam ,Cell Survival ,business.industry ,Radiochemistry ,Cancer therapy ,Bragg peak ,Penetration (firestop) ,Carbon ,Salivary Glands ,Cell killing ,Oncology ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Carbon Radioisotopes ,Low dose rate ,Irradiation ,business ,Nuclear medicine ,Clonogenic assay ,Relative Biological Effectiveness - Abstract
Purpose: To evaluate the potential importance of radioactive 9 C-ion beam in cancer radiotherapy. Methods and Materials: Human salivary gland (HSG) cells were exposed to a double-radiation-source 9 C beam at different depths around the Bragg peak. Cell survival fraction was determined by standard clonogenic assay. For comparison, the same experiment was conducted for a therapeutic 12 C beam. To determine relative biologic effectiveness (RBE) values, HSG cells were also irradiated with 60 Co γ-rays of fractionation scheme as the reference. Results: The 9 C beam was more efficient in cell killing at the depths around its Bragg peak than was the 12 C beam, which corresponded to the 9 C-ion stopping region and where delayed low-energy particles were emitted. The RBE value at 50% survival level for the 9 C beam varied from 1.38 to 4.23. Compared with the 12 C beam, the RBE values for the 9 C beam were always higher; an increase in RBE by a factor of up to 1.87 has been observed at the depths distal to the Bragg peak. Conclusion: The potential advantage of radioactive 9 C-ion beam in cancer therapy has been revealed at low dose rate in comparison with a therapeutic 12 C beam. This observation, however, remains to be investigated at therapeutic dose rates in the future.
- Published
- 2005
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