1. Department of Experimental Radiology and Health Physics, University of Fukui School of Medical Sciences, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan
2. Institute for Environmental Sciences, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan
3. Department of Biological Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
4. Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
5. Department of Environmental Health Sciences, Oita University of Nursing and Health Sciences, Oita 870-1201, Japan
6. Department of Radiation Effects Research, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba 263-8555, Japan
7. Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1, Oookayaka, Meguro-ku, Tokyo 152-8550, Japan
8. Department of Charged Particle Therapy Research, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba 263-8555, Japan