The Effects of Small Doses of Ionizing Radiation Fundamental Biophysical Characteristics

Abstract

From an application of the concepts of microdosimetry to a wide range of radiobiological data on higher organisms, it has become apparent that the first step in the biological action of ionizing radiation is the induction of subcellular lesions. Two basic characteristics of this process are that it depends only on the first and (sometimes) the second power of the absorbed dose and that the yield of such lesions, as well as the magnitude of the domain where energy concentration determines the yield of lesions, is relatively constant even for cells and effects that differ greatly in radiosensitivity. These observations have led to the formulation of the theory of dual radiation action, which postulates that the yield of these lesions depends on the square of the specific energy in domains having an effective diameter which differs from 1 μm by much less than an order of magnitude. It has furthermore been deduced that lesions are produced by the interaction of pairs of sublesions which are presumed to be alt...