BNCT research activities at the Granada group and the project NeMeSis: Neutrons for medicine and sciences, towards an accelerator-based facility for new BNCT therapies, medical isotope production and other scientific neutron applications.

The Granada group in BNCT research is currently performing studies on: nuclear and radiobiological data for BNCT, new boron compounds and a new design for a neutron source for BNCT and other applications, including the production of medical radioisotopes. All these activities are described in this report.

Simple analytical expressions for the dose of point photon sources in homogeneous media.

The contributions to the dose of a point photon source in homogeneous media due to primary and first, second, ..., nth scattered photons are investigated. Assuming a simple statistical model, an analytical form comes out for each of these contributions. It includes a polynomial and a single exponential and depends on three parameters which have a physical meaning. The values of these parameters for different energies and for water, as a test case, are obtained from numerical fits to the results of a Monte Carlo simulation with the code PENELOPE. The average differences between the model and the Monte Carlo results, after the fitting process, are below 1%. Our model permits to obtain improved versions of the classical approach of Berger in a straightforward way. The expressions obtained also describe the dose build-up of the primary photons.