A study of cell survival in mammalian cells exposed to spatially correlated triads of protons

Cellular survival results for late-S Chinese hamster V79 cells exposed to triads of protons of variable mean separations are reported. The data are analyzed within the framework of the Theory of Dual Radiation Action [8]. This analysis provides a new estimation of the function gamma (chi) representing the probability of two energy transfers separated by the distance chi to produce a lesion. In agreement with an earlier study [6] involving pairs of deuterons, it is concluded that: a) the process of lesion formation depends strongly on the relative separation of energy deposition events, and b) intratrack and intertrack lesions correspond to substantially different separations of pairwise energy transfers.