The cytogenetic dosimetry of recent accidental overexposure

When accidental exposure to ionizing radiations is suspected, optimal choic e of a treatment strategy requires, in addition to information about the cl inical signs and physical dosimetry, a determination by biological paramete rs of the dose received. The scoring of unstable chromosomal aberrations in peripheral blood lymphocytes is the current reference method. Preparation of these samples depends on the goal sought - an exact assessment of severa l irradiations or rapid triage in the case of a large-scale accident. Moreo ver. some adaptation may be necessary if the irradiation is either heteroge nous or not recent. Despite the robustness and adaptability of this procedu re, conventional cytogenetics remains a tedious and time-consuming techniqu e, and it requires specialized staff. Scoring micronuclei in binucleated ly mphocytes may be an easier, simpler alternative to a dicentric assay. This paper. which is based on the experience acquired by the IPSN in recent year s in expert assessment of suspected radiations, has as its goal to provide a succinct technical guideline of these different approaches, as they are a dapted to suspected recent irradiation and triage.