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Published on: May 9, 2014
UK laboratory intercomparison on internal dosimetry
1AWE, Aldermaston, Berks, UK.
Insights
UK laboratories achieved satisfactory agreement in internal dose assessments using updated ICRP models. However, variability was noted in complex intake scenarios involving multiple radionuclides and wound contamination.
Area of Science:
- Medical Physics
- Radiation Protection
- Radiological Dosimetry
Background:
- This study details the first UK intercomparison of internal dose assessments employing the International Commission on Radiological Protection's (ICRP) revised Human Respiratory Tract and biokinetic models.
- Four participating UK laboratories assessed six distinct intake scenarios.
Observation:
- Overall agreement in committed effective dose (e(50)) assessments was satisfactory, with 79% of results falling within +/- 40% of the median.
- The smallest range in dose estimates (1.2) was observed for a Cesium-137 inhalation case.
- The largest range (6.0) occurred in a complex wound and potential inhalation case involving Plutonium-238, Plutonium-239, and Americium-241.
Findings:
- Variability in dose assessment was attributed to decisions regarding data selection for intake estimation.
- Differences in parameter choices for the ICRP models contributed to inter-laboratory variation.
- The impact of Diethylenetriaminepentaacetic acid (DTPA) treatment on dose assessment also introduced variability.
Implications:
- While generally satisfactory, the intercomparison highlights areas for improvement in internal dose assessment consistency, particularly for complex exposure situations.
- Standardization of data selection and model parameterization is crucial for enhancing the reliability of internal dose assessments.
- Further research may be needed to refine methodologies for complex intakes involving mixed radionuclides and non-inhalation routes.
Abstract:
A laboratory intercomparison for internal dose assessment from a variety of intake scenarios is described. This is the first UK intercomparison using the revised ICRP Human Respiratory Tract and biokinetic models. Four United Kingdom laboratories participated and six cases were assessed. Overall, the agreement in internal dose assessments between laboratories was considered satisfactory with 79% of the assessed committed effective doses, e(50), for cases within a band of +/- 40% of the median value. The range (highest/lowest) in e(50) estimated by the laboratories was smallest (1.2) for a case involving inhalation of 137Cs. The range was greatest (6.0) for a case involving a wound with, and possible inhalation of, 238Pu, 239Pu and 241Am; the variation between laboratories in assessment of intakes could not be considered to be satisfactory in this case. Judgements on the most appropriate data to use in estimating intakes, choice of parameter values for use with the ICRP models and allowing for the effects of treatment with DTPA were important sources of variability between laboratories.
