Proceedings of the British Institute of Radiology, International particle therapy meeting. 7 June 1991

The conventional radiation beams used at the present time, X rays, gamma rays and electrons, leave much to be desired from the physical point of view. An ideal radiation would give a uniform dose (or whatever is desired) to the tumour and zero outside. Of the unconventional radiations now in use, fast neutron beams provide no advantage over X and gamma rays in this respect. Their advantage can only be biological and is under assessment in at least 17 centres around the world.