The International Commission on Radiation Units and Measurements (ICRU) Report Number 95 (2020 Operational quantities for external radiation exposure ICRU Rep. 95 J. ICRU 20) recommends new definitions ffor operational quantities as estimators of the International Commission on Radiological Protection radiation protection quantities. As part of this report, dose coefficients for neutron fluences are included for energies from 10−9–50 MeV. For lens of the eye dosimetry, several changes in the ICRU recommended quantities are of particular interest. First, an updated eye model is used that includes segmentation of the sensitive lens region. In addition, the use of absorbed dose instead of dose equivalent has been selected as the appropriate operational quantity since deterministic (i.e. non-stochastic) effects are of primary importance for the lens of the eye. The ICRU report also addresses computational parameters, such as absorbed dose tally volumes, depths, source areas and source rotational angles. In this work, neutron dose coefficients calculated for the lens of the eye in support of the ICRU report are presented. Dose coefficients for mono-energetic neutrons and reference neutron spectra are presented. The source is a parallel beam, and the mono-energetic dose coefficients are provided for rotational angles with respect to the front face of the head ranging from 0°–90°. In addition, monoenergetic dose coefficients for the parallel beam incident on the back of the head (180°) and for a rotational source geometry where the head is irradiated from all angles are reported. For all scenarios, absorbed doses to the complete lens and the sensitive volume of each eye were calculated. Eye lens absorbed dose coefficients, D p,slab(3,0)/Φ, were also calculated in an ICRU tissue slab phantom at a depth of 3 mm for a parallel beam irradiating the slab perpendicular to the front face, and these results are compared to the values determined using the eye phantom.

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As part of a broader effort to calculate effective dose rate coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, soil or water, age-specific stylized phantoms have been employed to determine dose coefficients relating dose rate to organs and tissues in the body. In this article, dose rate coefficients computed using the International Commission on Radiological Protection reference adult male voxel phantom are compared with values computed using the Oak Ridge National Laboratory adult male stylized phantom in an air submersion exposure geometry. Monte Carlo calculations for both phantoms were performed for monoenergetic source photons in the range of 30 keV to 5 MeV. These calculations largely result in differences under 10 % for photon energies above 50 keV, and it can be expected that both models show comparable results for the environmental sources of radionuclides.

The Oak Ridge National Laboratory Center for Radiation Protection Knowledge (CRPK) has undertaken a number of calculations in support of a revision to the United States Environmental Protection Agency (US EPA) Federal Guidance Report on external exposure to radionuclides in air, water and soil (FGR 12). Age-specific mathematical phantom calculations were performed for the conditions of submersion in radioactive air and immersion in water. Dose rate coefficients were calculated for discrete photon and electron energies and folded with emissions from 1252 radionuclides using ICRP Publication 107 decay data to determine equivalent and effective dose rate coefficients. The coefficients calculated in this work compare favorably to those reported in FGR12 as well as by other authors that employed voxel phantoms for similar exposure scenarios.