Belousov Alexandr Vitalyievich RussiaMoscowMoscow State University. M.V. Lomonosov, 119991, Russian Federation, Moscow, Leninskie gory, 1доцентbelousovav@physics.msu.ru Author's articles Effect of Secondary Particles with High Linear Energy Transfer on Photon Beam Quality Factor Calculation and Approximation of Radial Dose Function of Iridium Sources