Photon radiation quality factor energy dependence for personal dose equivalent calculation}

Using the Monte Carlo computer simulation (Geant4 code), the energy dependence of the personal dose equivalent $H_p(0.07), H_p(3), H_p(10)$ of photon radiation with energies up to 40 MeV in water phantom was estimated. To estimate the energy dependence of $ H_p $, the calculation of linear energy transfer (LET) averaged by dose of all types of secondary particles in a thin layer of a sensitive detector located at depths of 0.07, 3 and 10 mm, respectively, is performed. It is shown that in the given range of photon energies, the quality factor equal to the ratio $ H_p / D $, where $ D $ is the absorbed dose, can differ significantly from the value recommended for photons of all energies equal to unity. The main reason for the increase in the quality factor is due to the large contribution of photonuclear reaction products.