Medical Radiology and Radiation Safety. 2013. Vol. 58. No. 1. P. 5–28

RADIATION SAFETY

B.A. Napier¹, M.O. Degteva², N.B. Shagina², L.R. Anspaugh³

Uncertainty Analysis for the Techa River Dosimetry System

1. Pacific Northwest National Laboratory, Richland, WA, USA; 2. Urals Research Center for Radiation Medicine, Chelyabinsk, Russia, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. ; 3. University of Utah, Salt Lake City, UT, USA

Abstract

Purpose: Estimation of uncertainties in the doses for the members of the Techa River Cohort (TRC) with a two-dimensional Monte Carlo approach.

Material and methods: In order to provide more accurate and precise estimates of individual dose (and thus more precise estimates of radiation risk) for the members of the TRC, the Techa River Dosimetry System used. The deterministic version of the improved dosimetry system TRDS-2009D was basically completed in April 2009. Recent developments in evaluation of dose-response models in light of uncertain dose have highlighted the importance of different types of uncertainties in the development of individual dose estimates. Thus, the TRDS-2009 parameters were analyzed accordantly. These include uncertain parameters that may be either shared (common to some or all individuals) or unshared (a unique value for each person whose dose is to be estimated) within the dosimetric cohort. The nature of the type of uncertainty may be aleatory (random variability of true values due to stochastic processes) or epistemic (due to lack of complete knowledge about a unique quantity). Finally, there is a need to identify whether the structure of the errors is either related to measurement (the estimate differs from the true value by an error that is stochastically independent of the true value; frequently called classical uncertainty) or related to grouping (the true value varies from the estimate by an error that is random and is independent of the estimate; frequently called Berkson uncertainty).

Results: An approach has been developed that identifies the nature of the various input parameters and calculational methods incorporated in the Techa River Dosimetry System (based on the TRDS-2009D implementation), and a stochastic calculation model has been prepared to estimate the uncertainties in the dose estimates. This article reviews the concepts of uncertainty analysis, the equations, and input parameters, and then identifies the authors’ interpretations of their general nature.

Conclusions: It presents the approach selected so that the stochastic, Monte-Carlo, implementation of the dosimetry system TRDS-2009MC provides useful information regarding the uncertainties of the doses.

Key words: uncertainty analysis, radiation dosimetry, Techa River

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