Neutron and photon dose rate distributions in linac rooms

In the X-ray irradiation of the 18 MeV electron linac, the spatial distributions of neutron and photon ambient dose equivalent rates were measured by ADC plastic dosimeter and Optical Stimulated Luminescence dosimeter in the linac room. The spatial distributions were measured on the surface of the linac device, the irradiation room and the maze pathway. The calculations were executed for three types of linac head models with the MCNP5 code. The calculated accuracy of the spatial distribution was evaluated by comparing the measured results. The calculation-to-experiment ratios (C/E) of dose rates by the detailed linac head models converged to the range from 0.8 to 5. The radioactivities of the concrete of linac room floor were measured and compared with the calculated result.