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Title: Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study

Abstract

This report describes the results of a pilot study of the reliability of the biokinetic and dosimetric models currently used by the U.S. Nuclear Regulatory Commission (NRC) as predictors of dose per unit internal or external exposure to radionuclides. The study examines the feasibility of critically evaluating the accuracy of these models for a comprehensive set of radionuclides of concern to the NRC. Each critical evaluation would include: identification of discrepancies between the models and current databases; characterization of uncertainties in model predictions of dose per unit intake or unit external exposure; characterization of variability in dose per unit intake or unit external exposure; and evaluation of prospects for development of more accurate models. Uncertainty refers here to the level of knowledge of a central value for a population, and variability refers to quantitative differences between different members of a population. This pilot study provides a critical assessment of models for selected radionuclides representing different levels of knowledge of dose per unit exposure. The main conclusions of this study are as follows: (1) To optimize the use of available NRC resources, the full study should focus on radionuclides most frequently encountered in the workplace or environment. A list of 50more » radionuclides is proposed. (2) The reliability of a dose coefficient for inhalation or ingestion of a radionuclide (i.e., an estimate of dose per unit intake) may depend strongly on the specific application. Multiple characterizations of the uncertainty in a dose coefficient for inhalation or ingestion of a radionuclide may be needed for different forms of the radionuclide and different levels of information of that form available to the dose analyst. (3) A meaningful characterization of variability in dose per unit intake of a radionuclide requires detailed information on the biokinetics of the radionuclide and hence is not feasible for many infrequently studied radionuclides. (4) The biokinetics of a radionuclide in the human body typically represents the greatest source of uncertainty or variability in dose per unit intake. (5) Characterization of uncertainty in dose per unit exposure is generally a more straightforward problem for external exposure than for intake of a radionuclide. (6) For many radionuclides the most important outcome of a large-scale critical evaluation of databases and biokinetic models for radionuclides is expected to be the improvement of current models. Many of the current models do not fully or accurately reflect available radiobiological or physiological information, either because the models are outdated or because they were based on selective or uncritical use of data or inadequate model structures. In such cases the models should be replaced with physiologically realistic models that incorporate a wider spectrum of information.« less

Authors:
 [1];  [1];  [2]
  1. ORNL
  2. U.S. Nuclear Regulatory Commission
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
Work for Others (WFO)
OSTI Identifier:
939651
Report Number(s):
ORNL/TM-2008/131
401001060; TRN: US0806879
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 97; MATHEMATICAL MODELS; ACCURACY; INGESTION; INHALATION; RADIOISOTOPES; RELIABILITY; DOSIMETRY; RADIONUCLIDE KINETICS

Citation Formats

Leggett, Richard Wayne, Eckerman, Keith F, and Meck, Robert A. Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study. United States: N. p., 2008. Web. doi:10.2172/939651.
Leggett, Richard Wayne, Eckerman, Keith F, & Meck, Robert A. Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study. United States. doi:10.2172/939651.
Leggett, Richard Wayne, Eckerman, Keith F, and Meck, Robert A. Wed . "Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study". United States. doi:10.2172/939651. https://www.osti.gov/servlets/purl/939651.
@article{osti_939651,
title = {Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study},
author = {Leggett, Richard Wayne and Eckerman, Keith F and Meck, Robert A.},
abstractNote = {This report describes the results of a pilot study of the reliability of the biokinetic and dosimetric models currently used by the U.S. Nuclear Regulatory Commission (NRC) as predictors of dose per unit internal or external exposure to radionuclides. The study examines the feasibility of critically evaluating the accuracy of these models for a comprehensive set of radionuclides of concern to the NRC. Each critical evaluation would include: identification of discrepancies between the models and current databases; characterization of uncertainties in model predictions of dose per unit intake or unit external exposure; characterization of variability in dose per unit intake or unit external exposure; and evaluation of prospects for development of more accurate models. Uncertainty refers here to the level of knowledge of a central value for a population, and variability refers to quantitative differences between different members of a population. This pilot study provides a critical assessment of models for selected radionuclides representing different levels of knowledge of dose per unit exposure. The main conclusions of this study are as follows: (1) To optimize the use of available NRC resources, the full study should focus on radionuclides most frequently encountered in the workplace or environment. A list of 50 radionuclides is proposed. (2) The reliability of a dose coefficient for inhalation or ingestion of a radionuclide (i.e., an estimate of dose per unit intake) may depend strongly on the specific application. Multiple characterizations of the uncertainty in a dose coefficient for inhalation or ingestion of a radionuclide may be needed for different forms of the radionuclide and different levels of information of that form available to the dose analyst. (3) A meaningful characterization of variability in dose per unit intake of a radionuclide requires detailed information on the biokinetics of the radionuclide and hence is not feasible for many infrequently studied radionuclides. (4) The biokinetics of a radionuclide in the human body typically represents the greatest source of uncertainty or variability in dose per unit intake. (5) Characterization of uncertainty in dose per unit exposure is generally a more straightforward problem for external exposure than for intake of a radionuclide. (6) For many radionuclides the most important outcome of a large-scale critical evaluation of databases and biokinetic models for radionuclides is expected to be the improvement of current models. Many of the current models do not fully or accurately reflect available radiobiological or physiological information, either because the models are outdated or because they were based on selective or uncritical use of data or inadequate model structures. In such cases the models should be replaced with physiologically realistic models that incorporate a wider spectrum of information.},
doi = {10.2172/939651},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Oct 01 00:00:00 EDT 2008},
month = {Wed Oct 01 00:00:00 EDT 2008}
}

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