Analysis of the time relationship for the interaction of X-ray induced primary breaks in the formation of dicentric chromosomes.

In split-dose experiments, the time relationship for the interaction of primary breaks in the formation of dicentric chromosomes was analysed. Human peripheral lymphocytes were irradiated with a dose of 340 R of 220 kV X-rays split into two equal fractions separated by intervals up to 360 min. Assuming an exponential decline of the time-dependent quadratic component of the dose realtion of dicentrics a theoretical formula was deduced. Fitting this formula to the empirical data a mean time of 110 min could be calculated in which primary breaks induced by both dose-fractions can interact to form dicentric chromosomes.