NEUTRON FLUXES IN RADIOTHERAPY ROOMS

The spatial distribution of the neutron flux, originated in an electro n accelerator therapy room when energies above the threshold of (gamma ,n) and (e,e'n) reactions are employed, is physically due to a direct flux, coming from the accelerator head, and to a flux diffused from th e walls. In this work, the flux is described to a high degree of appro ximation by a set of functions whose spatial behavior is univocally de termined by the angular distributions of the neutrons emitted from the shield of the accelerator head and diffused from the walls. The analy tical results are verified with an extended series of Monte Carlo simu lations obtained with the MCNP code.