1. Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Japan
2. Research Center for Nuclear Physics, Osaka University, Suita, Japan
3. Department of Accelerator and Medical Physics, National Institute of Quantum and Radiological Science and Technology, Chiba, Japan
4. Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences, Maebashi, Japan
5. Faculty of Medicine, University of Tsukuba, Tsukuba, Japan