Neutron spectra around medical treatment facilities

The neutron field condition in and around the treatment room of the neutron therapy facility at the research reactor FRM in Garching-München was studied for radiation protection purposes. Neutron spectrometry was conducted by using a 15-channel multisphere spectrometer. From the unfolded spectral shapes, averaged dose conversion coefficients were derived and correction factors for the reading of two neutron monitors obtained. These results were compared with further measurements done at a medical linear accelerator where the neutrons are produced by (γ, n) processes in the irradiation head.