LET dependence of yield ratios of radiation-induced intra- and interchromosomal aberrations in human lymphocytes

Abstract

Purpose: To investigate the LET dependence of various yield ratios of intra- and interchromosomal aberrations in order to quantify proximity effects for illegitimate rejoining of chromosome breaks. Materials and methods: Calculations are based on 13 human lymphocyte data sets obtained from in vitro irradiation experiments with various radiation qualities covering an LET range of 0.5 to 150 keV/ mu m. A total of 93 000 first-division metaphases was analysed for all categories of chromosome-type aberrations. Results: No dose dependence was found for the various yield ratios of chromosomal aberrations. No LET dependence became apparent for the yield ratio of inter- to intrachromosomal exchange-type aberrations (dicentrics/centric rings F value). However, a clear LET dependence was found for the yield ratio of intra-arm intrachanges to inter-arm intrachanges (interstitial deletions/centric rings G ratio) and for the yield ratio of intraarm intrachanges to interchromosomal exchanges (interstitial deletions/dicentrics H ratio). Conclusion: Measurements of intrachanges are informative for interpretation and quantification of proximity effects in the formation of radiation-induced chromosome aberrations. In particular, yield ratios for intra-arm intrachanges are likely to have a high potential as an indicator of high-LET radiations.