Calculated neutron dose rates for implantable californium-252 sources

Fast neutron absorbed dose rates near 252 Cf finite line sources in several infinite tissue compositions have been calculated. The neutron flux produced by a point source was calculated using the one-dimensional energy-dependent discrete ordinates computer code, DTF-IV. The calculations utilized an S-16 angular quadrature approximation, 21 energy groups and anisotropic scattering up to the third order in the cosine of the scattering angle. The kerma from a point source was obtained from the flux, using recently calculated kerma-fluence factors. The absorbed dose rates for line sources were obtained by using the point source kerma as a kernel and integrating over the length of the source, assuming charged particle equilibrium.