Distortion of fast-neutron dose distribution by bone

The influence of bone on dose distributions due to fast neutrons generated at the Naval Research Laboratory (NRL) Cyclotron was investigated. A paired dosimeter consisting of a parallel-plate, tissue-equivalent ionization chamber and thermoluminscent material was used to partition the absorbed dose into neutron and gamma-ray components. Several thicknesses of bone were simulated using bone-equivalent liquid and plastic. Based on these measurements, the authors conclude that, as a result of the increased absorption of neutrons by bone, lower dose levels are found behind bone would be predicted from dose distributions in muscle-equivalent liquid.