BNCT dosimetry: peculiarities and methods

Dosimetry in tissue exposed to the epithermal neutron beams utilized for BNCT is complex, due to the multiplicity of the possible neutron reactions and consequently of the secondary radiation that contains photons, charged particles and recoil nuclei. Owing to the different radiobiological effectiveness of the various components of the absorbed dose, it is necessary to attain the evaluation of each of them. In addition, the spatial distributions of these dose components changes considerably with size and shape of the irradiated volume. Therefore, BNCT dosimetry requires suitably developed calculations and experimental methods. In this work, Monte Carlo simulations in phantoms of different sizes and shapes have been developed. Experimental methods for separating the dose components, mainly based on gel dosimeters and thermoluminescence detectors, have been applied. Moreover, the change in the absorbed dose resulting from the addition of 157Gd was investigated. Both measurements and calculations have been done with the BNCT epithermal beam of the LVR-15 reactor.