I am involved in the development of a beta- probe for Radio-Guided Surgery, the CHIRONE project of INFN, with the Applied Radiation Physics Group (ARPG) of the University of Rome “Sapienza”. My activity was focused on the development of Monte Carlo (MC) simulations of the detector, including the simulation of the optical photons production in the scintillating crystal and their propagation therein. I developed also a code to simulate the behavior of the probe in the surgical environment, this simulation reproduce the patient density, chemical composition and uptake of radiopharmaceutical. Such a MC simulation has been also used to predict the probe performances with new potential radiopharmaceutical. Moreover, I studied the tools and the protocols to characterize and validate the performances of different probe prototypes finalized to its use in a clinical environment. I also participated in pre-clinical ex-vivo tests on meningioma patients.