1. Oncology Center, Osaka University Hospital, Suita, Osaka 565-0871, Japan
2. Nippon Life Hospital, Nishi-ku, Osaka 550-0006, Japan
3. Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
4. Department of Radiation Therapy, Japanese Red Cross Society Kyoto Daiichi Hospital, Kyoto 605-0981, Japan