1. Department of Radiology Hamamatsu University School of Medicine 1-20-1 Handayama Hamamatsu, Shizuoka 431-3192, Japan.
2. Division of Radiation Oncology Shizuoka Cancer Center Hospital 1007 Shimonagakubo Nagaizumi, Shizuoka 411-8777, Japan.
3. Department of Informatics Hamamatsu University School of Medicine 1-20-1 Handayama 431-3192 Hamamatsu, Shizuoka, Japan