This study investigates the effects of low-energy photons on superficial and radiosensitive biological samples using the GEANT4 Monte Carlo simulation toolkit. Mass energy absorption coefficients were calculated for elements from hydrogen to calcium (Z = 1 to 20) within the photon energy range of 0.1 to 10 keV. Based on these coefficients, key radiological parameters, including the gamma constant, dose rate, and KERMA, were determined for various biological tissues and tissue-equivalent materials, such as water, adipose tissue, skin, eye lens, blood, and polymethyl methacrylate (PMMA). The simulation results were compared with available reference datasets to evaluate their consistency. Below 1 keV, validation was possible only for the elements hydrogen, carbon, nitrogen, and oxygen and using Hubbell’s tabulated data, whereas for the remaining elements, the comparison was performed with XCOM values above 1 keV. The largest deviation between GEANT4 and Hubbell data was observed for carbon (13.57%) at 0.2 keV, while the maximum deviation relative to XCOM data was 12.3% for chlorine at 8 keV. For the investigated composite materials, the highest difference was obtained for water, with a value of 5.74%. These results confirm the reliability of GEANT4 low-energy photon models and validate their applicability for accurately modeling dose distributions in complex biological and tissue-equivalent materials. The findings contribute to improved dosimetric accuracy in medical physics applications such as diagnostic imaging and superficial radiotherapy.
Parsaei et al. (Mon,) studied this question.