 This is a single BNCT-facility, non-randomized, non-comparative, prospective, open-label, phase III trial to determine the value of BNCT in the treatment of subjects who have undergone surgery for glioblastoma, but glioblastoma has not been treated with radiation therapy or chemotherapy. The neutron irradiation site is the FiR 1 reactor site, located at Otaniemi, Espoo, Finland, about 6 kilometers from the Helsinki University Central Hospital, Helsinki, where patient evaluation and post-irradiation care will take place. 