Comparison of fast neutron beams for radiotherapy produced by 17.3‐MeV deuterons incident on beryllium and deuterium targets

Fast neutron beams produced by 17.3‐MeV deuterons incident on a totally stopping beryllium target, a totally stopping deuterium gas target, and a 5.8‐MeV‐thick deuterium‐gas target are compared. It is shown that the deuterium‐gas target yields a significantly higher average energy and dose rate and may offer other advantages as well.