RENEB Inter-Laboratory Comparison 2021: The FISH-Based Translocation Assay

Area of Science:

• Radiation biology
• Cytogenetics
• Biophysical dosimetry

Background:

• Translocation analysis using fluorescence in situ hybridization (FISH) is crucial for assessing past ionizing radiation exposure.
• Inter-laboratory comparisons for FISH-based dose assessment are less common than for other methods like dicentric analysis.
• The European Network of Biological and Physical retrospective Dosimetry (RENEB) 2021 inter-laboratory comparison provided an opportunity to evaluate FISH performance.

Purpose of the Study:

• To conduct an inter-laboratory comparison using the FISH technique for radiation dose assessment.
• To gain experience with FISH-based dose assessment in a simulated emergency scenario.
• To evaluate the consistency and accuracy of FISH translocation analysis across multiple laboratories.

Main Methods:

• Peripheral blood samples from a healthy volunteer were irradiated with known doses (0, 1.2, 3.5 Gy) and sent to seven participating laboratories.
• Laboratories applied their standard FISH techniques for translocation analysis.
• Results were reported based on triage analysis (fewer cells) and full analysis (500 cells), with dose estimations provided.

Main Results:

• Most laboratories successfully discriminated between unexposed and irradiated samples.
• Triage analysis showed heterogeneity in cell counts, while full analysis was more homogeneous.
• Excluding outlier results, mean dose estimations showed deviations from delivered doses, with a general tendency to overestimate.

Conclusions:

• FISH is a viable method for discriminating irradiated from non-irradiated samples in retrospective dosimetry.
• Harmonization efforts are needed to improve the accuracy and consistency of FISH-based dose assessment.
• Further inter-laboratory exercises are recommended to address the observed overestimation of radiation doses.