 Boron Neutron Capture Therapy BNCT is an experimental radiation therapy technique that is based on the principle of irradiating boron atoms with neutrons. When neutrons have relatively low energy, boron atoms that have been targeted to cancerous tissue using a suitable boron carrier an amino acid derivative called BPA, boronophenylalanine will capture the neutrons. As a result from the neutron capture the boron atoms will split into two, producing helium and lithium ions. The helium and lithium ions, in turn, have only a short pathlength in tissue about 5 micrometers and will deposit their cell damaging effect mainly within the tumor provided that the boron carrier BPA has accumulated in the tumor. In practice, the study participants will receive BPA as an approximately 2-hour intravenous infusion, following which the tumor is irradiated with low energy epithermal neutrons obtained from a nuclear reactor at the BNCT facility. BNCT requires careful radiation dose planning, but neutron irradiation will last approximately only for one hour. In this study BNCT is given only once. The study hypothesis is that glioblastoma tissue may accumulate the boron carrier compound, and glioblastoma might respond to BNCT. 