Sources of fast neutrons for radiotherapy

There is currently great interest in the use of fast neutrons for radiotherapy. Although it is too early for the long-term effects to be known, the results so far are encouraging. Three types of fast neutron-producing devices are available: neutron generators, compact cyclotrons and large cyclotrons. For the requirements of radiotherapists the most suitable and practical source currently available is the reaction 9Be(d,n) in conjunction with a large cyclotron capable of accelerating deuterons to energies greater than 35 MeV.