[1] Univ Tsukuba, Grad Sch Comprehens Human Sci, Doctoral Programs Funct & Regulatory Med Sci, Dept Neurosurg, Tsukuba, Ibaraki 3058575, Japan
[2] Univ Hosp Tsukuba, Dept Neurosurg, Tsukuba, Ibaraki 3058575, Japan
[3] Univ Tsukuba, Grad Sch Comprehens Human Sci, Doctoral Program Adv Biomed Applicat, Dept Radiat Oncol, Tsukuba, Ibaraki 3058575, Japan