In recent years, the nuclear reaction known as proton-boron fusion has been thoroughly investigated, because it has been proposed as a suitable agent capable of significant improvements in cancer therapy with protons. Thereby, precise knowledge about physical properties involved represents the main strategy to assess actual potential of the proposed treatment method based on proton-boron fusion. In this work, the effective reaction cross section is studied from a theoretical point of view, and a direct application to the inelastic collisions distribution provided by Monte Carlo simulations is reported, weighting the importance of the reaction in the energy deposition process, and hence providing useful insight in the localized nature of the technique.