TOOTH ENAMEL DOSE COEFFICIENTS OF THE ICRP ADULT MESH-TYPE REFERENCE COMPUTATIONAL PHANTOMS FOR IDEALIZED EXTERNAL NEUTRON EXPOSURES.

Abstract

For application in electron paramagnetic resonance (EPR) dosimetry for neutron fields, the present study establishes a dataset of tooth enamel dose coefficients (DCs) for idealized external neutron exposures using the adult mesh-type reference computational phantoms (MRCPs) of the International Commission on Radiological Protection (ICRP). PHITS Monte Carlo neutron transport simulations were performed to compute DCs for buccal and lingual enamels for the front, front-left, front-right, left, and right teeth for 68 monoenergetic neutrons under antero-posterior (AP), posteroanterior (PA), left-lateral (LLAT), right-lateral (RLAT), rotational (ROT), and isotropic (ISO) irradiation geometries. The dose contributions from primary neutrons and secondary photons were quantified to account for the respective sensitivities of enamel to neutrons and photons in EPR measurements. The results demonstrated meaningful variation in enamel DCs with irradiation geometry; for example, up to a 5.6-fold difference was observed between the AP and PA geometries for the front lingual enamel. In addition, the results showed that for neutron energies below 20 MeV, secondary photons contributed more than 10% to the total dose, emphasizing the need for separate consideration of primary neutrons and secondary photons when interpreting EPR signals. The neutron enamel DCs established in the present study, in combination with the previously derived photon enamel DCs, will enable improved estimation of individual radiation doses, including organ and effective doses, for realistic mixed neutron-photon exposure scenarios.