Evaluation of a moderator assembly for an accelerator based epithermal neutron source

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:200401

Blue, T E ^[1]

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1. Ohio State Univ., Columbus, OH (United States)

Previously, the authors have evaluated a moderator/reflector assembly design for an accelerator-based epithermal neutron irradiation facility (AENIF) for Boron Neutron Capture Therapy (BNCT) on the basis of parameters which are calculated in air. Beam design for BNCT is evolving from being based on beam parameters in air to being based on beam parameters in head phantoms. It has been recognized for some time that beam parameters in air lack clinical relevance. However, more clinically relevant parameters based on biological effects in patients` heads, besides being complicated (through their dependence on absorbed dose distributions) by their dependence on head dimensions, necessarily incorporate factors relating absorbed doses in tissues to biological effects. These factors, such as RBE`s and compound factors were, in the judgment of most beam designers, not known in the past with sufficient accuracy to justify the added complexity of basing beam designs on parameters based on dose distributions in head phantoms. In this paper, the authors discuss the basis for their design of an epithermal neutron field for an accelerator source of neutrons for BNCT. In their presentation, they discuss development of a spectrum-dependent neutron normal-tissue RBE which is normalized to RBE measurements in dogs. They also review the treatment planning methodology of Gahbauer and discuss how this treatment planning methodology is modified and merged with their spectrum-dependent neutron normal-tissue RBE to create a beam design methodology with beam optimization parameters which account for the effects of fractionation and neutron flux energy spectra. Finally, they discuss the application of their beam design methodology and beam optimization parameters to the analysis of the combinations of moderator and reflector materials and thicknesses that they evaluated previously on the basis of parameters which were calculated in air.

• OSTI ID: 200401
• Report Number(s): CONF-941129--
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
55 BIOLOGY AND MEDICINE
BASIC STUDIES
DESIGN
EPITHERMAL NEUTRONS
HEAD
MODERATORS
NEUTRON CAPTURE THERAPY
NEUTRON REFLECTORS
NEUTRON SOURCES
RBE