Importance de la normalisation en radioprotection : le cas de la dosimétrie biologique

Ph. Voisin Congrès national SFRP, Tours, 19-21 juin 2001

When individuals are accidentally overexposed to ionizing radiations, radiation protection programs include dose assessment by means of biological parameters. While several of them could be good candidates as biodosimeters, unstable chromosome aberrations (dicentrics, centric rings and acentrics) scoring in blood peripheral lymphocytes is still regarded as the most specific and most significant method to estimate the exposure dose. It acquired in some countries a medico-legal value. Even if this technique remains a simple adaptation of those classically used in pathological cytogenetics, paradoxically there are no universally adopted rules to get this technique comparable from one laboratory to another. Some important discrepancies can be noticed, concerning as much methodological aspects as quality of results. The only document being able to supply a reference base for the standardization of this method is the 1986 IAEA technical report. Nevertheless neither the ‘86 report, nor the new one which goes out in 2001, solve crucial problems such as the context of service laboratory and the needs of assurance quality program. The significant role played by the biological dosimetry in many countries has proved necessary to standardize this technique, in a compatible way with the national rules of the interested countries. An ISO (International Standardization Organization) working group (WG18) for the normalization of the biological dosimetry was so created within the framework of the Technical Committee 85/Sub-Committee 2 (TC85/SC2) on the radiation protection. It held its first meeting at the end of 1999. It includes scientists of Germany, Belgium, Canada, Spain, United States, Finland, France, Italy, Japan, Poland and Sweden as well as a representative of the IAEA. On the basis of a consensus between the members of the group, immediate program consists in writing a normative text putting minimal constraints allowing to homogenize and to make comparable this technique in all the laboratories practicing it. This text has to establish an internal quality program (methodology, depiction of results and interpretation, storage) as well as external quality program including intercomparison and reference laboratories. The problem of the confidentiality of clinical data and results is also evoked, as this notion covers a lot of different aspects according to countries. A first complete text ( " Working Draft " ) should be achieved in 2001. The structure of the draft at the present state of achievement will be presented as well as some prospective on the future works.