A BNCT neutron generator using a 30 MeV proton beam

An epithermal neutron generator for boron neutron capture therapy (BNCT) has been developed, which utilizes the (p, xn) reaction of tantalum induced by 30 MeV protons. The heat deposited by protons is a high power of 22.5kW and removed by coolant water. The integrity of the tantalum target was confirmed by hydraulic analysis with the STAR-CD code and also thermal and stress analyses with the ANSYS code. The neutron spectrum is shaped by iron and FLUENTALTM moderators and epithermal neutrons are obtained. The neutron generator is equipped with two collimators, horizontal and vertical irradiation holes, to facilitate patient setting. Neutrons emitted at 90 degrees with the proton beam are used so that the contamination of fast neutron dose can be reduced. The shapes of the moderator and the collimator are optimized by neutronics calculations with the MCNPX code and a high epithermal neutron flux has been obtained at the aperture of the collimator. (author)