The insertion of gold nanoparticles in biological liquids, tissues and organs permits to increase the equivalent atomic number of the medium that, if used as target to be irradiated by ionizing radiation, permits an increment of the absorbed dose. No toxic nanoparticles, such as the Au, can be injected in the cancer tissues at different concentrations before using a localized treatment that uses energetic proton beams for radiotherapy. Due to the high density and atomic number of the used gold nanoparticles, the absorbed radiation dose can be increased to about a factor six per cent using relatively low concentration of nanoparticles injectable as solution in the tumor tissue. This means to reduce the exposition to ionizing radiation or to increase the dose to the tumor site. Simulation programs of proton energy loss in tissues, using SRIM Code, are employed to evaluate the Bragg peak enhancing in presence of Au nanoparticles, so it will be presented and discussed. Some research findings and patents in the gold nanoparticle preparation and application to Medicine are reviewed in the present paper.