Moderated 252Cf neutron energy spectra in brain tissue and calculated boron neutron capture dose.

While there is significant clinical experience using both low- and high-dose (252)Cf brachytherapy, combination therapy using (10)B for neutron capture therapy-enhanced (252)Cf brachytherapy has not been performed. Monte Carlo calculations were performed in a brain phantom (ICRU 44 brain tissue) to evaluate the dose enhancement predicted for a range of (10)B concentrations over a range of distances from a clinical (252)Cf source. These results were compared to experimental measurements and calculations published in the literature. For (10)B concentrations </=50 microg/g, the (10)B neutron capture dose enhancement was small in comparison to the (252)Cf fast neutron dose.