An Investigation of Cell Displacement in Direct and Indirect DNA Damage Induced by Photon Radiation: A Geant4-DNA Study

Purpose: This study aimed to investigate the biological effects of photon radiation and its potential for cancer treatment through targeted radiation therapy by studying direct and indirect DNA damage induced by 15, 30, and 50 keV photon radiation using Geant4-DNA Monte Carlo simulations. Materials and Methods: Two spherical cells (C and C2) and their cell nucleus were modeled in liquid water. An atomic DNA model constructed in the Geant4-DNA Monte Carlo simulation toolkit, containing 125,000 chromatin fibers, was placed inside the nucleus of the C2 cell. The number of direct and indirect Single-Strand Breaks (SSBs), Double-Strand Breaks (DSBs), and hybrid double-strand breaks (HDSB) in the C2 cell caused by 15, 30, and 50 keV photons were calculated for N2←CS, N2←Cy, N2←C, and N2←N Target←Source combinations, at the distances of 0, 2.5, and 5 μm between two cells. Results: Low energy (15 keV) photons emitted within the cell surface and the cell cytoplasm resulted in the highest DNA damage, producing markedly higher SSBs, DSBs, and HDSBs compared to the whole cell and the nucleus sources across 0-5 μm target distances. Increasing the photon energy to 30 and 50 keV showed 81-96% reduced DNA damage. Additionally, the 2.5 μm target distance decreased DSBs up to 53%. Conclusion: Based on the results, 15 keV photons are more effective for the inhibition or control of cancer cells.