Neutron capture therapy with 235U seeds.

A combination of brachytherapy and neutron capture therapy has been evaluated using 235U metal seeds and external neutron beam irradiation. When thermal neutrons are absorbed by 235U, high-energy neutrons and gamma rays are produced and some of these deposit energy in surrounding tissue. A Monte Carlo program, using the code MCNP, has been used to evaluate two sizes of 235U seeds in a water phantom. The results of flux suppression around the seeds and dose distributions are illustrated and discussed. The results show that high doses can be delivered in a relatively short time by using 235U seeds with neutron capture therapy. This therapy with multiple needles or seeds can be envisioned as a substitute for traditional brachytherapy to give an effective killing dose.