Biological dosimetry for mixed gamma-neutron field

Abstract

Historically, cytogenetic biodosimetry assays have been based on quantifying asymmetrical chromosome alterations in mytogen-stimulated T-lymphocytes in their first mitosis after radiation exposure. Increased levels of chromosome damage are a sensitive indicator of radiation exposure and they are routinely exploited for assessing radiation absorbed dose after accidental or occupational exposure.  However there are few curves for neutron gamma mixed field available in the world, which impairs the cytogenetic studies of changes in nuclear disasters involving such radiation. In this paper the dose–response curve was measured for the induction of chromosomal alterations in peripheral blood lymphocytes after chronic exposure in vitro to neutron-gamma mixes field. Blood was obtained from one healthy donor and exposed to two neutron-gamma mixed fields from sources 241AmBe at the Neutron Calibration Laboratory (NCL – CRCN/NE – PE – Brazil). The evaluated absorbed doses covered the range 0.2-1.6 Gy. The dicentric chromosomes were observed at metaphase, following colcemid accumulation in well-spread metaphases.  Results showed a linear-quadric dependence between radiations absorbed dose and dicentric chromosomes frequencies expressed by Y = 0.0009 + 0.172D + 0.0496D2. Dose response curve described in this paper will contribute to the development of Brazilian nuclear research