Search

Abstract The efficacy of accelerator-based boron neutron capture therapy was examined through relative-biological-effectiveness dose calculations with the fast-neutron dose per epithermal neutron (FNR) and the 10B concentration as parameters. In the case of a tumor 10B concentration of 65 ppm, the treatment efficacy depended more strongly on the FNR when the normal-tissue 10B concentration was 0.65 ppm, which would be brought about by the administration of an advanced chemical compound, than when the 10B concentration was 18 ppm, which is attainable by the use of boronophenylalanine. Highlights • The efficacy of accelerator-based BNCT is examined by in-phantom RBE dose calculations. • The irradiation is simulated with a fast-neutron dose per epithermal neutron (FNR) as a parameter. • The in-phantom RBE dose is calculated with a normal-tissue 10B density (N) as a parameter. • The treatment efficacy greatly varies with FNR and N, when N is smaller than 4 ppm. • This effect will be noted when an advanced chemical compound will be applied to BNCT. [ABSTRACT FROM AUTHOR]

Fuel configurations for a subcritical neutron multiplier, which was embedded in a beam-shaping assembly and irradiated by electrons from a linear accelerator, were examined to maximize the production of the epithermal neutron flux for boron neutron capture therapy. The epithermal neutron flux at the treatment position increased as the area per uranium fuel plate increased and was estimated to be 2 × 10 9 cm −2 s −1 when the subcritical neutron multiplier was irradiated by a 4.4 kW (0.22 mA) beam of 20 MeV electrons. [ABSTRACT FROM AUTHOR]

We are developing a fiber type two-dimentional (2-D) position-sensitive detector having a spatial resolution less than 0.5 mm in order to use it in the time-of-flight (TOF) measurement. The detector performance was examined, and some experiments on the TOF radiography were performed using this detector. The results indicated that the detector could be applied successfully to the TOF measurement and that the TOF radiography was very useful since it gave more informative data than those obtained by the conventional radiography using a broad energy band. [ABSTRACT FROM AUTHOR]

Characteristics of a beam-shaping assembly that utilizes photo-neutrons from irradiation of a tungsten target by electrons from an accelerator were examined to produce a beam of neutrons suitable for boron neutron capture therapy. The epithermal neutron flux per kilowatt of electron-beam power almost increased to a maximum as the energy of the initial electrons was increased to 42.5 MeV, but the fast-neutron dose and the photon dose per epithermal neutron hardly changed on varying the energy of the initial electrons. • Beam characteristics of an electron LINAC neutron source for BNCT were examined. • Energy of electrons incident on a photo-neutron-generation target was optimized. • The epithermal neutron flux was almost saturated at an electron energy of 42.5 MeV. • The fast-neutron dose per epithermal neutron hardly changed with electron energy. • The photon dose per epithermal neutron also hardly varied with the electron energy. [ABSTRACT FROM AUTHOR]

Abstract: We studied the energy resolution of the pulsed neutron beam of the Accurate Neutron–Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex/Materials and Life Science Experimental Facility (J-PARC/MLF). A simulation in the energy region from 0.7meV to 1MeV was performed and measurements were made at thermal (0.76−62meV) and epithermal energies (4.8−410eV). The neutron energy resolution of ANNRI determined by the time-of-flight technique depends on the time structure of the neutron pulse. We obtained the neutron energy resolution as a function of the neutron energy by the simulation in the two operation modes of the neutron source: double- and single-bunch modes. In double-bunch mode, the resolution deteriorates above about 10eV because the time structure of the neutron pulse splits into two peaks. The time structures at 13 energy points from measurements in the thermal energy region agree with those of the simulation. In the epithermal energy region, the time structures at 17 energy points were obtained from measurements and agree with those of the simulation. The FWHM values of the time structures by the simulation and measurements were found to be almost consistent. In the single-bunch mode, the energy resolution is better than about 1% between 1meV and 10keV at a neutron source operation of 17.5kW. These results confirm the energy resolution of the pulsed neutron beam produced by the ANNRI beamline. [Copyright &y& Elsevier]