International intercomparison on internal dose assessment (ICIDOSE 2017)

Internal dose assessment intercomparison exercises are useful tools: to verify the performance of an Internal Dosimetry Service; to promote the harmonization of dose assessments; and to identify weaknesses where further improvements are necessary. However, no such international inter-comparisons have been performed for more than 10 years. In the period May 2014 - May 2016, the "Technical Recommendations for Monitoring Individuals for Occupational Intakes of Radionuclides" were developed at the initiative of the European Commission, and later published within the EC Radiation Protection series, as RP 188. In 2017 the Working Group "Internal Dosimetry" of the European Radiation Dosimetry Group (EURADOS) organised a new intercomparison action, named ICIDOSE 2017, with the main aim of testing the practical applicability of these Technical Recommendations (RP188). Four case-studies were proposed to participants: an artificially created case of inhalation of 60Co to simulate a simple special monitoring case; a real case of inhalation of 125I, with simple routine monitoring; a real and more complex case of incorporation of 234+235+238U, featuring both confirmatory and special monitoring; and a complex real case of an accidental incorporation of 241Am, including multiple administrations of DTPA. Results were received from 66 participants from 26 countries; these were compared to reference or recommended solutions, developed for each case based on the application of RP 188. The results were discussed at a workshop in October 2018, at the Federal Office for Radiation Protection (BfS, Munich, Germany). The observed spread of the submitted results was improved from those obtained from similar cases in previous intercomparison exercises, showing that the availability of RP 188 significantly contributes to the harmonization of the internal dose assessment process.