# Physics of atomic nucleus and elementary particles

## Calculation and Approximation of Radial Dose Function of Iridium Sources

**Background and Objectives:** The purpose of this paper is to investigate optimal fitting parameters for approximating radial dose function of Iridium sources. Calculations were performed using written by authors source code based on GEANT4 library package designed to simulate particle transport processes using Monte–Carlo method. **Results:** Following parameters of the source were determined: dose rate constant, radial dose function and anisotropy function. Obtained satisfactory coherence with other researchers’ data.

## Effect of Secondary Particles with High Linear Energy Transfer on Photon Beam Quality Factor

The energy dependence is investigated for a monoenergetic photon radiation quality factor with energies up to 40 MeV, while passing through a thin layer. The conditions of irradiation simulate radiobiological experiments to determine the relative biological eectiveness. The quality factor is calculated on the basis of data on linear energy transfer of all the particles in the irradiated layer, which are calculated using the Monte–Carlo method using GEANT4 code.