The effect of bone on dose distributions produced by the Fermi National Laboratory fast-neutron beam

The dose distortion produced by bone during fast-neutron therapy was studied using a target-to-skin distance of 153 cm, with beams 10 x 10 field size at the surface of a phantom. Doses were measured using several muscle-equivalent ionization chambers in the phantom. Results showed that the dose was reduced by interposing bone-equivalent material between the point in question and the surface of the phantom.