Another approach to improve the dose conformity is to use charged particles like protons instead of the conventional X- and γ-rays. Protons exhibit a specific depth-dose distribution which allows to achieve a more targeted dose deposition and a significant sparing of healthy tissue behind the tumor. In particular proton therapy has therefore become a routinely prescribed treatment for tumors located close to sensitive structures. Moreover, the track structure and energy transfer of protons is different from those of photons which can provide advantages in terms of biological effectiveness. Also, the application of nanotechnology in radiotherapy also offers interesting approaches to improve the therapeutic index. Therefore, in this work, we first introduce the water phantom and simultaneously inject high-energy protons into it through a pencil beam and 50 nm nanoparticles with different concentrations and investigate the increase in the absorbed dose. Then, we present a more realistic model of brain tumor and study the increase in the absorbed dose in the activated tumor in two cases with and without the injection of gold, silver and platinum nanoparticles into the brain phantom. The simulation software used in this article is GEANT4. As can be seen from this work, the absorbed dose with the injection of nanoparticles at an energy of 150 MeV is, in order, from highest to lowest, related to platinum, gold, silver and finally water without the injection of nanoparticles, and this is due to the fact that the number of secondary electrons produced by platinum is more than gold, gold is more than silver and silver is more than water (Pt>Au>Ag>W). And the optimum energy deposited in the Bragg curve at the end of the brain tumor is 110 MeV.
