The TOP-IMPLART, a new proton therapy facility, is under development in Frascati ENEA Laboratories, near Rome. The project is centered on a medium-energy proton accelerator designed as a sequence of modular linear accelerators (the final energy will be 230 MeV). Being not a commercial product, measurements and simulation are fundamental to characterize the system and the radiation field, even during its construction. In this work some preliminary evaluations of the neutron contamination have been tried. The simulations were validated through some measurements obtaining a satisfactory agreement. A more detailed calculations and measurements campaign is scheduled for the next future.