Biologically effective doses from californium-252 intracavitary applications.

Californium-252 which emits fission neutrons and gamma rays is being investigated for applications in brachytherapy. From available experimental results, a value of 6.2 had been arrived at as the RBE for cell killing of californium neutrons relative to radium gavva rays for intracavitary applications based on the revised Manchester system of loading. The LET distributions as well as the ratio of neutron to gamma dose-rates have been estimated and are found to remain almost constant in the volume of interest around such applications.