Аннотация:Gold nanoparticles attract attention for the use in radiation therapy of tumors due to the ability to enhance the efficacy of ionizing radiation. The magnitude of the radiosensitizing effect depends on the parameters of the nanoparticle, in particular on the modification of the surface. In the present work, the spectrum of secondary particles generated in a gold nanoparticle virtually irradiated with 60 Со gamma rays as a result of surface modification by a polyethylene glycol shell was studied. The Monte Carlo calculations revealed that modification of the nanoparticle's surface changes the spectrum of secondary particles. The most robust was the loss in low-energy electrons (51%) whereas the yield of Compton electrons increased by 1.27 times. At the same time, no statistically significant changes were observed in the spectrum of secondary photons and photoelectrons. Simulation of the formation and distribution of secondary electron radiation makes it possible to evaluate the parameters important for the rational design of antitumor nanoradiosensitizers based on chemical elements with a high atomic number.