MICRONUCLEUS INDUCTION IN HUMAN-LYMPHOCYTES - COMPARATIVE EFFECTS OF X-RAYS, ALPHA-PARTICLES, BETA-PARTICLES AND NEUTRONS AND IMPLICATIONS FOR BIOLOGICAL DOSIMETRY

The cytokinesis-block micronucleus assay in peripheral blood lymphocyt es has the potential for being a simple and rapid method for biologica l dosimetry. This technique has been used to study the induction of mi cronuclei in the blood from 12 donors after exposure to a range of rad iations with track-averaged LET values ranging from 0.26 to 44 keV mu m(-1). Data based on the average response of the 12 individuals for 25 0 kVp X rays were found to agree well with results published previousl y from other laboratories using similar techniques. Low dose-limiting RBE values relative to 250 kVp X rays for the radiations studied were found to be 0.50 for strontium/yttrium-90 beta particles, 6.9 for 20-2 3 keV mu m(-1) alpha particles and 17 for 24 keV neutrons. The pattern of the variation of individual radiosensitivity was found to be compl ex and dependent on dose, and the evaluation of individual radiosensit ivity based on the response at one dose only can be misleading. It is concluded that, although the cytokinesis-block micronucleus assay in b lood lymphocytes is a radiobiologically appropriate technique to use f or biological dosimetry, its practical implementation may be limited b y a need to perform individual pre-exposure calibrations. (C) 1996 by Radiation Research Society