Estimating Exposure Fraction from Radiation Biomarkers: A Comparison of Frequentist and Bayesian Approaches

Abstract

If individuals are exposed to ionising radiation, due to some radiation accident, for medical reasons, or during spaceflight, there is often a need to estimate the contracted radiation dose. The field of biodosimetry is concerned with estimating the dose retrospectively, based on certain biomarkers, which are typically based on counts of some cytogenetic or biomolecular features of the cell arising after radiation-induced double-strand-breaks. Such techniques face particular challenges when the exposure is only partial rather than whole-body, which, when unaccounted for, may lead to grossly inaccurate dose estimates. For biomarkers which are overdispersed, there are currently no procedures available for the detection of partial-body exposures. We consider the question of estimating the exposure fraction as well as quantifying its uncertainty, using Bayesian and frequentist methods, by means of simulation scenarios which are motivated by foci count data as arising for the γ−H2AX protein biomarker.