Untitled

Abstract

One of the two overriding conditions for successful BNCT is that there must be a sufficient number of thermal neutrons delivered to each of the boronated cells in the tumour bed (target volume). Despite the poor experience with BNCT in the USA some 40 years ago, the continued apparent success of BNCT in Japan since 1968, lead indirectly to the re-start of clinical trials on BNCT in 1994 at both Brookhaven and MIT. Similar trials will start soon at Petten in Europe. At other centres worldwide, many neutron beam designs are being proposed with either thermal or epithermal neutrons, emanating predominantly from nuclear research reactors. It is apparent that whilst the success of BNCT depends on a suitable neutron beam, there is a diversity in available designs, as well as each proposed type of neutron source, with consequently different characteristics of the emergent neutron beam. The paper presents the historical development of neutron beams used for BNCT, addresses the requirements on the types of beams, describes some of the existing designs and other proposals elsewhere and lastly, considers the broader requirements in designing NCT facilities. The focus of the paper is on treatment of brain cancer, neutron beam requirements for other types of cancer may vary.

Current status of boron neutron capture therapy of high grade gliomas and recurrent head and neck cancer

“…The general characteristics of neutron beams for NCT are described in detail elsewhere [43] and the requirements for a facility capable of high patient through-put have been discussed by Harling [44]. Two approaches have been used for the design of epithermal neutron irradiation facilities at fission reactors.…”

The Chemistry of Neutron Capture Therapy

“…72 These beams can deliver acceptable neutron fluences to tumors that may be 3-6 cm below the surface and has been the basis for the development of beams with suitable fluxes of epithermal neutrons. 73 Presently, the available beams are not monoenergetic nor do they possess a narrow energy spectrum. They contain thermal, epithermal, and fast neutrons, as well as gamma rays.…”

Chromosomal aberrations in peripheral blood lymphocytes exposed to a mixed beam of low energy neutrons and gamma radiation

“…Other possible reactions where gamma radiation is induced are 14 N(n, γ ) 15 N (cross-section: 79.8 mbarn) and 16 O(n, γ ) 17 O (cross-section: 0.19 mbarn) (Gambarini et al 2000, IAEA 2006. The low LET component of the beam is often augmented by the fact that epithermal and thermal beams are generated in a nuclear reactor and are accompanied by gamma radiation that is generated in the reactor core (Moss et al 1997). This gamma beam is referred to as incident gamma.…”