BNCT: Status and dosimetry requirements

BNCT is a binary cancer treatment modality, consisting of the delivery of a suitable boron compound to tumour cells followed by irradiation of the tumour by thermal neutrons. Originally proposed by Locher in 1936, the first clinical trials at Brookhaven and at MIT in the 1950s were unsuccessful because of the non-selectivity of the boron compound used. New classes of boron carriers have since been developed and neutron sources have been optimised. Since 1968 more than 100 patients have been treated in Japan. Clinical studies have again started in the USA (1994 at MIT and BNL) and are expected soon to begin in Europe. Basic principles of this treatment modality and general requirements for boron compounds and reactor or accelerator based neutron sources are reviewed. Complexities involved in macro- and microdosimetry and thus the biological evaluation of baron compounds are discussed.