The physical basis of the biological effects of high voltage radiations

Abstract

The ranges in mm. of secondary high speed electrons produced in cells by irradiation with x-rays of various wave-lengths are tabulated, (a) for photoelectrons (from data on Al), and (b) for recoil electrons (by use of the Klein-Nishina equation). The range of the latter rises rapidly in the [gamma]-ray region of wave-lengths. From both effects, there is obtained the curve of the probability of a cell of 5[mu] diam. being traversed by an electron per unit of absorbed energy at various wavelengths. On the assumption that 1 and more than 1 electron passage may be required to produce a biological effect, survival curves are calculated for a mass of cells irradiated at various wave-lengths, and used in a discussion of the selective action of x-rays on rapidly growing tissues.