In 2023, REPROLAM organized an Occupational Internal Dose Evaluation Intercomparison with the objective of verifying the response capacity in the evaluation of the effective dose committed in internal exposure scenarios with relevant radionuclides in the occupational field. This initiative brought together services, laboratories, groups, and end users (SDIs) involved in internal dosimetry, to apply the new biokinetic and dosimetric models of the recently published ICRP OIR series.

The exercise protocol included four cases, as well as the methodology for evaluating the effective dose committed, covering different levels of complexity and specific objectives. The cases included: dose evaluation for the incorporation of I-131 and Tc-99m in confirmatory monitoring at a nuclear medicine center, routine monitoring of natural uranium, accidental ingestion of H-3, and an optional case study on an accidental incorporation of I-131.

This article presents a detailed analysis of the results obtained by the participants in each case evaluated, using a robust statistical method based on the ISO 13528:2015 standard. A total of 21 SDIs from 14 countries participated. The analysis of results allowed us to obtain a general description of the state of internal dosimetry in the Ibero-American region for individual monitoring of occupational exposure, as well as to identify the lessons learned for the region.

The intercomparison exercise was a significant step in understanding and improving the methodologies used in internal dosimetry. By engaging a diverse group of participants from multiple countries, the initiative not only facilitated a comprehensive evaluation but also promoted the sharing of best practices and the harmonization of internal dosimetry procedures across the region. The findings highlighted the varying levels of expertise and resources available to different SDIs, underscoring the need for ongoing training and support to ensure consistent and accurate dose evaluations.

Furthermore, the exercise underscored the importance of adopting the latest biokinetic and dosimetric models, as outlined in the ICRP OIR series, to enhance the accuracy of dose assessments. The collaborative effort also provided valuable insights into the practical challenges and limitations faced by SDIs in the region, paving the way for targeted improvements in internal dosimetry practices.