Assessing DNA damage and relative biological effectiveness of the secondary electrons in gadolinium neutron capture therapy using an adapted Geant4-DNA

Abstract

The aim of this study is to assess the impact of internal conversion (IC) and Auger electrons released during gadolinium neutron capture therapy (157GdNCT) on the amount of DNA damage induced and the relative biological effectiveness (RBE) across varying cellular structures and types. We developed cell models that featured simplified chromosome geometries with diverse shapes and base pair densities, utilizing the Geant4-DNA package. The RBE values of these secondary electrons were determined based on the DNA double-strand breaks (DNA-DSBs) endpoint. The findings revealed that the more the distribution of gadolinium is concentrated in the nucleus, the greater the degree of DNA damage. In the cytoplasm, the influence of secondary electrons on DNA damage were not related to cell shape. However, when the secondary electrons were distributed in the nuclear membrane, the RBE of the secondary electrons was affected by the cell shape. When there is a greater difference in base pair density, more pronounced discrepancies in the yield of DSBs are evident. As the base pair density decreased, the yield of DSBs increased. Furthermore, the yield of DSBs exceeded 8.63 ± 0.33 DSBs/Gy/Gbp under different influencing factors. The RBE range of IC electrons and Auger electrons released from 157GdNCT based on DNA-DSBs endpoints was found to be between 0.8 and 1.6.