  Bremsstrahlung photon beams produced by medical linear accelerators are
currently the most commonly used method of radiation therapy for cancerous
tumors. Photons with energies greater than 8-10 MeV potentially generate
neutrons through photonuclear interactions in the accelerator's treatment head,
patient's body, and treatment room ambient. Electrons impinging on a heavy
target generate a cascade shower of bremsstrahlung photons, the energy spectrum
of which shows an end point equal to the electron beam energy. By varying the
target thickness, an optimum thickness exists for which, at the given electron
energy, maximum photon flux is achievable. If a source of high-energy photons
i.e. bremsstrahlung, is conveniently directed to a suitable D2O target, a novel
approach for production of an acceptable flux of filterable photoneturons for
boron neutron capture therapy (BNCT) application is possible. This study
consists of two parts. 1. Comparison and assessment of deuterium photonuclear
cross section data. 2. Evaluation of the heavy water photonuclear source.
