Synthesis and characterization of a soft-tissue substitute for neutron dosimetry

Tsuda, Shuichi  ; Endo, Akira   ; Yamaguchi, Yasuhiro

To develop a physical phantom for neutron dosimetry, a solid soft-tissue substitute was synthesized. The hydrogen and oxygen compositions of the synthesized tissue substitute, NAN-JAERI, are similar to those of the soft tissue in ICRU Report 44. To examine the radiation characteristics of the new soft-tissue substitute, absorbed dose distributions in NAN-JAERI were measured using a Cf neutron source. The measured absorbed dose distributions of neutrons and photons agree with those calculated by a Monte Carlo simulation code MCNP. The agreement between the experiment and the simulation verifies this method of evaluating the soft-tissue equivalence of NAN-JAERI for Cf neutrons. Similar simulations for some mono-energetic neutron sources showed that the newly developed tissue substitute has soft-tissue equivalent characteristics in the neutron energy range up to 14 MeV, in terms of the absorbed dose distributions in a slab phantom.