Evaluation of neutron doses in Brazilian aircrew by the Monte Carlo method

The demand for air travel has intensified over the last few decades and, accordingly, studies seeking to assess the levels of exposure to cosmic radiation that aircrew and frequent passengers are subject to have attracted more and more interest. Aircrew, for frequently manning high altitude flights, appear as professionals directly exposed and prone to the risks arising from cosmic radiation. Continuous exposure to particles of cosmic origin can lead to dose levels above the regulatory limits for public exposure, with neutrons being the particles of the highest contribution to the dose. In several countries around the world, aircrew already have regulatory control in terms of radiological protection and are classified as occupationally exposed. In Brazil, however, there is neither a regulatory control nor a specific classification for these professionals. The objective of this work is to estimate both the neutron component of the effective dose and the effective dose of Brazilian aircrew due to cosmic rays using the GEANT4 Monte Carlo toolkit. For the estimation of the effective dose, the EXPACS code was used to estimate the neutron flux and GEANT4 to obtain the doses on the selected flights. The GEANT4 simulations were performed in the flight conditions and with ICRP voxel phantoms. The neutron doses obtained ranged from 0.002 to 3.0 mSv on the different selected flights. The equivalent doses of neutrons, in certain organs, were also estimated. In the end, the total effective doses were presented, with the contribution of neutron doses, and, when compared with the annual dose limits for members of the public and occupationally exposed workers, they showed that aircrew could receive dose levels above the public limit. A comparison was made with experimental dose measurements throughout the Brazilian territory.