Biological dosimetry intercomparison exercise: an evaluation of triage and routine mode results by robust methods

DI GIORGIO M.; BARQUINERO F.; VALLERGA M.B.; RADL A.; TAJA M.R.; SEOANE A.; DE LUCA J.C.; STUCK OLIVEIRA M.; VALDIVIA P.; GARCIA LIMA O.; LAMADRID A.; GONZALEZ MESA J.; ROMERO AGUILEIRA I.; MANDINA CARDOSO T.; GUERRERO CARVAJAL C.; ARCEO MALDONADO C.; ESPINOZA M.; MARTINEZ LOPEZ W.; DI TOMASSO M.; ROY L.; LINDHOLM C.; ROMM H.; GUCLU I.; LLOYD D.

RADIATION RESEARCH

RADIATION RESEARCH SOC

Lugar: Kansas; Año: 2011 vol. 175 p. 638 - 649

0033-7587

Nowadays biological dosimetry laboratories must have well-defined protocols and quality management standards. Participation in periodic proficiency testing by interlaboratory comparisons is also required. This harmonization is essential if a cooperation network is used to respond to a mass casualty?s event. Here is presented an international intercomparison performed in the framework of the IAEA Regional Latin America - RLA/9/054 Project. The exercise involved 14 laboratories, 8 from Latin America and 6 from Europe. The performance of each laboratory and reproducibility of the exercise was evaluated using robust methods described in ISO standards. The study was based on the analysis of slides from irradiated samples at 0.75 (DI) and 2.5 Gy (DII). Laboratories were required to score the frequency of dicentrics and convert to estimated doses, using their own dose-effect curves, after the analysis of 50, 100 cells (triage mode) and after conventional scoring of 500 cells or 100 dicentrics. In the conventional scoring, at both doses, all reported frequencies were considered as satisfactory, and two reported doses were considered as questionable. The analysis of the data dispersion among the dicentric frequencies and among doses indicated a better reproducibility for estimated doses (15.6% for DI and 8.8% for DII) than for frequencies (24.4% for DI and 11.4% for DII), expressed by the coefficient of variation. In the two triage modes, although robust analysis classified some reported frequencies or doses as unsatisfactory or questionable, all estimated doses were in agreement with the accepted error ± 0.5 Gy. However, at DI dose and for 50 scored cells, 5 out of the 14 reported confidence intervals, included zero dose and could be interpreted as false negatives. This improved with 100 cells where only one confidence interval included zero dose. At DII dose all estimations fell within ± 0.5 of the reference dose interval. The results obtained in this triage exercise indicated that is better to report doses than frequencies. Overall, in both, triage and conventional scoring modes the laboratory performances were satisfactory for mutual cooperation purposes. These data reinforce the view that collaborative networking in the case of a mass casualty event can be successful.