Generic Use of Uncertainties in Endpoint Predictions for Regulatory Purposes

Görtz, R.; Bath, N.; Berg, H.P.

doi:10.1093/oxfordjournals.rpd.a033163

Cited by 3 publications

(2 citation statements)

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“…However, for special cases, uncertainties can be very important to judge the reliability and the potential range of the dose and risk estimates for real individuals and situations. A quantitative analysis of internal dose can help to guide regulators in setting appropriate limits on intakes (Görtz et al 2000 ), to guide national and international organizations to invest scientific efforts for updating the models and dose coefficients (Bailey et al 2007 ), and to provide dose uncertainties for occupational workers (Henrichs 2007 ). Quantification of uncertainties can support the reliability of dose coefficients as regulatory dose limits and constraints (Puncher et al 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Uncertainty analysis in internal dose calculations for cerium considering the uncertainties of biokinetic parameters and S values

Spielmann

Zankl

et al. 2020

Radiat Environ Biophys

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Radioactive cerium and other lanthanides can be transported through the aquatic system into foodstuffs and then be incorporated by humans. Information on the uncertainty of reported dose coefficients for exposed members of the public is then needed for risk analysis. In this study, uncertainties of dose coefficients due to the ingestion of the radionuclides 141Ce and 144Ce were estimated. According to the schema of internal dose calculation, a general statistical method based on the propagation of uncertainty was developed. The method takes into account the uncertainties contributed by the biokinetic models and by the so-called S values. These S-values were derived by using Monte Carlo radiation transport simulations with five adult non-reference voxel computational phantoms that have been developed at Helmholtz Zentrum München, Germany. Random and Latin hypercube sampling techniques were applied to sample parameters of biokinetic models and S values. The uncertainty factors, expressed as the square root of the 97.5th and 2.5th percentile ratios, for organ equivalent dose coefficients of 141Ce were found to be in the range of 1.2–5.1 and for 144Ce in the range of 1.2–7.4. The uncertainty factor of the detriment-weighted dose coefficient for 141Ce is 2.5 and for 144Ce 3.9. It is concluded that a general statistical method for calculating the uncertainty of dose coefficients was developed and applied to the lanthanide cerium. The dose uncertainties obtained provide improved dose coefficients for radiation risk analysis of humans. Furthermore, these uncertainties can be used to identify those parameters most important in internal dose calculations by applying sensitivity analyses.

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Section: Introductionmentioning

confidence: 99%

Uncertainty analysis in internal dose calculations for cerium considering the uncertainties of biokinetic parameters and S values

Spielmann

Zankl

et al. 2020

Radiat Environ Biophys

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“…However, the model parameters are highly uncertain. A quantitative analysis of the uncertainty in the model inputs and outputs can guide regulators in setting appropriate limits on intake (Görtz et al 2000). In addition to the application in the nuclear safety assessment and in the environmental engineering models, the SA has, in association with an uncertainty analysis, been used in biokinetic models in internal dosimetry (Marsh and Birchall 2000;Bolch et al 2001Bolch et al , 2003Luciani et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Reliability of a New Biokinetic Model of Zirconium in Internal Dosimetry: Part Ii, Parameter Sensitivity Analysis

Greiter²,

Oeh³

et al. 2011

Health Physics

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The reliability of biokinetic models is essential for the assessment of internal doses and a radiation risk analysis for the public and occupational workers exposed to radionuclides. In the present study, a method for assessing the reliability of biokinetic models by means of uncertainty and sensitivity analysis was developed. In the first part of the paper, the parameter uncertainty was analyzed for two biokinetic models of zirconium (Zr); one was reported by the International Commission on Radiological Protection (ICRP), and one was developed at the Helmholtz Zentrum München-German Research Center for Environmental Health (HMGU). In the second part of the paper, the parameter uncertainties and distributions of the Zr biokinetic models evaluated in Part I are used as the model inputs for identifying the most influential parameters in the models. Furthermore, the most influential model parameter on the integral of the radioactivity of Zr over 50 y in source organs after ingestion was identified. The results of the systemic HMGU Zr model showed that over the first 10 d, the parameters of transfer rates between blood and other soft tissues have the largest influence on the content of Zr in the blood and the daily urinary excretion; however, after day 1,000, the transfer rate from bone to blood becomes dominant. For the retention in bone, the transfer rate from blood to bone surfaces has the most influence out to the endpoint of the simulation; the transfer rate from blood to the upper larger intestine contributes a lot in the later days; i.e., after day 300. The alimentary tract absorption factor (fA) influences mostly the integral of radioactivity of Zr in most source organs after ingestion.

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Parameter uncertainty analysis of a biokinetic model of caesium

Klein

Blanchardon³

et al. 2014

Radiation Protection Dosimetry

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Parameter uncertainties for the biokinetic model of caesium (Cs) developed by Leggett et al. were inventoried and evaluated. The methods of parameter uncertainty analysis were used to assess the uncertainties of model predictions with the assumptions of model parameter uncertainties and distributions. Furthermore, the importance of individual model parameters was assessed by means of sensitivity analysis. The calculated uncertainties of model predictions were compared with human data of Cs measured in blood and in the whole body. It was found that propagating the derived uncertainties in model parameter values reproduced the range of bioassay data observed in human subjects at different times after intake. The maximum ranges, expressed as uncertainty factors (UFs) (defined as a square root of ratio between 97.5th and 2.5th percentiles) of blood clearance, whole-body retention and urinary excretion of Cs predicted at earlier time after intake were, respectively: 1.5, 1.0 and 2.5 at the first day; 1.8, 1.1 and 2.4 at Day 10 and 1.8, 2.0 and 1.8 at Day 100; for the late times (1000 d) after intake, the UFs were increased to 43, 24 and 31, respectively. The model parameters of transfer rates between kidneys and blood, muscle and blood and the rate of transfer from kidneys to urinary bladder content are most influential to the blood clearance and to the whole-body retention of Cs. For the urinary excretion, the parameters of transfer rates from urinary bladder content to urine and from kidneys to urinary bladder content impact mostly. The implication and effect on the estimated equivalent and effective doses of the larger uncertainty of 43 in whole-body retention in the later time, say, after Day 500 will be explored in a successive work in the framework of EURADOS.

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Generic Use of Uncertainties in Endpoint Predictions for Regulatory Purposes

Cited by 3 publications

References 0 publications

Uncertainty analysis in internal dose calculations for cerium considering the uncertainties of biokinetic parameters and S values

Uncertainty analysis in internal dose calculations for cerium considering the uncertainties of biokinetic parameters and S values

Reliability of a New Biokinetic Model of Zirconium in Internal Dosimetry: Part Ii, Parameter Sensitivity Analysis

Parameter uncertainty analysis of a biokinetic model of caesium

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