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Michael Fikani - One of the best experts on this subject based on the ideXlab platform.

V. A. Nievaart - One of the best experts on this subject based on the ideXlab platform.

  • A parameter study to determine the optimal Source Neutron energy in boron Neutron capture therapy of brain tumours
    Physics in medicine and biology, 2004
    Co-Authors: V. A. Nievaart, Ray Moss, Jan Leen Kloosterman, T.h.j.j. Van Der Hagen, H. Van Dam
    Abstract:

    The values of the parameters used in boron Neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the 10B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal Source Neutron energy. For brain tumours it turns out that the 10B concentration, the RBE factors for 10B as well as fast Neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT Source Neutron energy. By using Source Neutrons of a few keV together with Neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour.

  • CALCULATING THE TUMOUR-SPECIFIC OPTIMAL Source Neutron ENERGY FOR BORON Neutron CAPTURE THERAPY WITH PARTICLE PRODUCTION AND ADJOINT MONTE CARLO TECHNIQUES
    2002
    Co-Authors: V. A. Nievaart, Ray Moss, J. L. Kloostermanand, T. H. J. J. Vander Hagen
    Abstract:

    This paper addresses the question as to whether it is useful to tailor the Neutron energy for optimal irradiation of a specific tumour location in BNCT. Consequently, forward and adjoint MCNP calculations have been performed in a slab shaped geometry with human head tissue. In the forward mode the alpha, proton and proton recoil productions are determined for a spherical shaped tumour positioned at five locations between 40 mm and 80 mm from the surface. The proton production in cranium is high for Source Neutron energies up to 100 eV. Above 100 keV Source Neutrons the dose due to recoiling protons increases rapidly. To get the highest alpha production in the tumour at 40 mm, 5 eV Source Neutrons should be used, increasing to around 1 MeV for a tumour at 80 mm. These maximum alpha productions in tumours at different positions have been taken as the starting points for the adjoint calculations. The adjoint flux for a tumour at 60 mm is uniformly shaped, just as in the forward result, where the alpha production is optimal for a wide spectrum of Source Neutron energies. The next steps will be to refine the used multigroup library for the adjoint calculations, to change the geometry to an ellipse-shaped head phantom and to apply the adjoint calculation to the other production components.

Robert C. Haight - One of the best experts on this subject based on the ideXlab platform.

H. Van Dam - One of the best experts on this subject based on the ideXlab platform.

  • A parameter study to determine the optimal Source Neutron energy in boron Neutron capture therapy of brain tumours
    Physics in medicine and biology, 2004
    Co-Authors: V. A. Nievaart, Ray Moss, Jan Leen Kloosterman, T.h.j.j. Van Der Hagen, H. Van Dam
    Abstract:

    The values of the parameters used in boron Neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the 10B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal Source Neutron energy. For brain tumours it turns out that the 10B concentration, the RBE factors for 10B as well as fast Neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT Source Neutron energy. By using Source Neutrons of a few keV together with Neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour.

Liliane Basso Barichello - One of the best experts on this subject based on the ideXlab platform.

  • An analytical approach for solving a nodal formulation of two-dimensional fixed-Source Neutron transport problems with linearly anisotropic scattering
    Progress in Nuclear Energy, 2017
    Co-Authors: C.b. Picoloto, R.d. Da Cunha, Ricardo C. Barros, Liliane Basso Barichello
    Abstract:

    Abstract In this work, the formulation of the Analytical Discrete Ordinates (ADO) method for two-dimensional fixed-Source Neutron transport problems is extended to problems with anisotropic scattering. The methodology is developed from the discrete ordinates approximation of the two-dimensional transport, whose equations are integrated transversally within homogenized regions of the domain, yielding one-dimensional equations for the average angular fluxes. Such one-dimensional equations are solved by the ADO method, after considering approximations for the transverse leakage terms, and their solutions are written in terms of eigenvalues and eigenfunctions. The relevant feature of the ADO method for the isotropic scattering cases, which reduced the order of the eigenvalue problems to half of the number of discrete directions, is also preserved for the present anisotropic cases. Explicit spatial variables expressions are derived for the average angular fluxes in regions of interest defined in the domain. The full domain solution is defined by the coupling of local solutions in different regions, without the use of sweeping procedures. As usual in nodal schemes, auxiliary equations are necessary and, in this case, the unknown region-edge angular fluxes are approximated by constants embedded in the Source term. Numerical results for region-average scalar fluxes are obtained and compared with the ones available in the literature to illustrate the feasibility of keeping the computational efficiency already verified in treating problems with isotropic scattering, with the use of the ADO method.