1 Department of Radiology, Nagoya University Graduate School of Medicine, Aichi, Japan; Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba, Japan.
2 Department of Radiation Oncology, National Cancer Center Hospital East, Chiba, Japan; Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba, Japan. Electronic address: hhojo@east.ncc.go.jp.
3 Department of Radiation Oncology, National Cancer Center Hospital East, Chiba, Japan; Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba, Japan.