International intercomparison on internal dose assessment (ICIDOSE 2017)

Area of Science:

• Radiological Protection
• Internal Dosimetry
• Occupational Health

Background:

• Internal dose assessment intercomparison exercises are crucial for verifying dosimetry services and promoting harmonized assessments.
• No international intercomparisons for internal dosimetry had been conducted for over a decade prior to this study.
• The European Commission developed 'Technical Recommendations for Monitoring Individuals for Occupational Intakes of Radionuclides' (RP188) between 2014-2016.

Purpose of the Study:

• To test the practical applicability of the RP188 recommendations through a new intercomparison action.
• To assess the performance of internal dosimetry services in occupational monitoring scenarios.
• To evaluate the harmonization of internal dose assessments across different participants and countries.

Main Methods:

• Organized the ICIDOSE 2017 intercomparison action by the European Radiation Dosimetry Group (EURADOS) Working Group 'Internal Dosimetry'.
• Proposed four distinct case studies: simulated 60Co inhalation, real 125I inhalation, complex 234+235+238U incorporation, and accidental 241Am incorporation with DTPA treatment.
• Collected results from 66 participants across 26 countries and compared them against reference solutions based on RP188.

Main Results:

• A small number of outliers were observed in the 60Co, 125I, and 241Am cases, with geometric standard deviations (GSDs) of 1.07, 1.04, and 1.43, respectively.
• The spread of results for these cases showed improvement compared to previous intercomparison exercises, indicating enhanced harmonization.
• A wider spread of results was noted for the uranium case due to uncertainties in exposure pathways and patterns, highlighting challenges in complex scenarios.

Conclusions:

• The ICIDOSE 2017 exercise successfully demonstrated the practical applicability and benefits of the RP188 recommendations.
• The RP188 guidelines contribute to improved harmonization in internal dose assessment for occupational radionuclide monitoring.
• Further attention may be needed for complex exposure scenarios, particularly those with unknown parameters, to refine assessment methodologies.