Development of thermal neutron moderator for testing boron agents for Boron Neutron Capture Therapy (BNCT)

We developed a thermal neutron source for performance tests of boron agents for Boron Neutron Capture Therapy (BNCT) at Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) in National Institute of Radiological Sciences, Japan. The thermal neutron flux at the experimental position was measured to be 2.18 x 10(8) n/cm(2)/s, the cadmium ratio was 9.21, and gamma ray dose ratewas 2.11 Gy/h. The neutron dose ratewas estimated to be 2.96 Gy/h. These values indicate that the neutron source can be applicable for tests of boron agents although application range is limited. An example of irradiation experiment is described.