Attenuation of 15 MeV neutrons in multilayer shields composed of steel, polyethylene and borated materials

Abstract

For the design of an efficient shield and collimator system for the application of 15 MeV neutrons from the ³H(d,n)⁴He reaction in radiotherapy, various aspects must be considered: (a) the dose to normal tissues outside the beam must be reduced to a sufficiently low level; (b) the shield thickness should be kept to a minimum because of the limited yields of neutrons from presently available generators; (c) the beam penumbra should be as small as possible; (d) the shield and beam shaping accessories should not be too heavy; (e) parts of the collimator which must be handled or are easily accessible must not become so strongly activated that they present health hazards.