Dosimetric Analysis of BEBIG 60Co and Flexisource 192Ir HDR Brachytherapy Sources using Geant4 Simulation

Background: This study validates the precision of dosimetric constraints for the BEBIG 60Co and Flexisource 192Ir Brachytherapy Sources using the Geant4 Monte Carlo code, commonly applied in clinical brachytherapy. Objective: The current study aimed to assess the effects of tissue heterogeneities on dosimetry by evaluating key parameters for the BEBIG 60Co and Flexisource 192Ir Brachytherapy Sources. Material and Methods: In this simulation study, the geometries of the BEBIG 60Co and 192Ir Flexi-sources were modeled within a water sphere. Key dosimetric parameters, including air kerma strength (SkS), dose rate constant (λ), radial dose function (g(r)), and anisotropy function (F(r,θ)) were calculated according to TG-43 and ESTRO standards. Results: The dose rate constants for BEBIG 60Co and 192Ir Flexi-sources were 1.079 cGy/h ±0.008 and 1.099 cGy/h ±0.01, respectively, with deviations of 0.73% and 0.91% from reference values. The radial dose function showed a maximum deviation of less than 2% at 15 cm for both sources, indicating strong agreement with the reference data. Conclusion: Geant4 Monte Carlo simulations provide precise validation of BEBIG 60Co and 192Ir Flexi-sources. The findings suggest that 60Co offers a dosimetric advantage by reducing exposure to nearby organs while effectively reaching distant tissues, potentially enhancing treatment precision and safety in clinical brachytherapy.