Variables in the radiation-attenuation of helminth larvae: the effect of differences in quality of radiation

Abstract

A comparison has been made of the attenuating effect on N. brasiliensis larvae of X-rays (HVL, 8 mm Al) and γ-rays from 60Co over the range 10–80 kr. In the dose range where attenuation was manifested as a decrease in total worm burden the γ-rays had an RBE (relative biological effect) of 0-7 relative to the X-rays as unity.Because of the enhancement of infectivity occurring at low radiation doses, attenuation in this region is better assessed in terms of alteration to the sex-ratio of the parasite rather than effect on total population.This work was supported by grants from the Agricultural Research Council and the Horse Race Betting Levy Board, and was carried out during the tenure by one of the authors (T. Kassai) of a British Council exchange scholarship.Thanks are due to Dr T. Martin Young and Mr J. S. Orr of the Radiotherapy Department, Western Infirmary, Glasgow, for access to radiation sources and helpful advice.