Survival of murine leukaemia cells exposed to 252 Californium neutrons under conditions simulating implantation of these sources into tssue in radiotherapy.

Abstract

Abstract Murine P-388 leukaemia cells have been irradiated with either radium γ rays, or the mixed fast neutron and γ emission from 252Cf, in a geometrical set-up simulating the use of such sources in brachyradiotherapy. Survival of reproductive capacity of the tumour cells was assayed in vivo. At the relatively high dose-rates used (circa 240–280 rads/ hour) the Relative Biological Effectiveness (RBE) of the fast neutrons from 252Cf was 2·7–3·8 for irradiation under aerobic conditions and 3·3–5 for irradiation in nitrogen. The Oxygen Enhancement Ratio (OER) was 2·3 for irradiation with radium γ rays and 1·9 for irradiation with 252Cf, a potential Therapeutic Gain Factor (TGF) circa 1·2 for the use of these sources in treatment of tumours containing significant proportions of hypoxic cells.