Original Paper

Radiation and Environmental Biophysics

, Volume 51, Issue 4, pp 411-423

Open Access This content is freely available online to anyone, anywhere at any time.

Effective dose conversion coefficients for radionuclides exponentially distributed in the ground

  • Kimiaki SaitoAffiliated withJapan Atomic Energy Agency, Uchisaiwai-cho Email author 
  • , Nobuhito IshigureAffiliated withGraduate School of Medicine, Nagoya University
  • , Nina Petoussi-HenssAffiliated withDepartment of Radiation Physics and Diagnostics, Helmholtz Zentrum München-German Research Center for Environmental Health
  • , Helmut SchlattlAffiliated withDepartment of Radiation Physics and Diagnostics, Helmholtz Zentrum München-German Research Center for Environmental Health

Abstract

In order to provide fundamental data required for dose evaluation due to environmental exposures, effective dose conversion coefficients, that is, the effective dose rate per unit activity per unit area, were calculated for a number of potentially important radionuclides, assuming an exponential distribution in ground, over a wide range of relaxation depths. The conversion coefficients were calculated for adults and a new-born baby on the basis of dosimetric methods that the authors and related researchers have previously developed, using Monte Carlo simulations and anthropomorphic computational phantoms. The differences in effective dose conversion coefficients due to body size between the adult and baby phantoms were found to lie within 50 %, for most cases; however, for some low energies, differences could amount to a factor of 3. The effective dose per unit source intensity per area was found to decrease by a factor of 2–5, for increasing relaxation depths from 0 to 5 g/cm2, above a source energy of 50 keV. It is also shown that implementation of the calculated coefficients into the computation of the tissue weighting factors and the adult reference computational phantoms of ICRP Publication 103 does not significantly influence the effective dose conversion coefficients of the environment. Consequently, the coefficients shown in this paper could be applied for the evaluation of effective doses, as defined according to both recommendations of ICRP Publications 103 and 60.

Keywords

Effective dose Conversion coefficients Ground source Exponential distribution Radionuclides