Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan. fukumitsun@yahoo.co.jp. Department of Radiation Oncology, Kobe Proton Center, 1-6-8, Minatojima-Minamimachi, Kobe, 650-0047, Japan. Department of Anesthesiology, Kobe Proton Center, Kobe, Japan. Department of Hematology and Oncology, Hyogo Children's Hospital, Kobe, Japan. Department of Neurosurgery, Hyogo Children's Hospital, Kobe, Japan.