A Geant4-DNA study on DNA damage induced by ¹⁶¹Tb and ¹⁷⁷Lu in a multicellular atomic model

Using the Geant4-DNA, direct and indirect SSBs (single strand breaks), DSBs (double strand breaks), and HDSBs (hybrid DSBs) induced by ¹⁶¹Tb and ¹⁷⁷Lu were quantified for different target-source configurations.

This study presents a multicellular (cluster) atomic model that contains the damage-specific DNA binding protein 2 (DDB2) DNA fragments within its cell nuclei. This model consists of 13 identical spherical cells arranged in a hexagonal close-packed configuration, where a central cell is surrounded by 12 neighboring cells. In order to make an accurate assessment of the simulations, the full beta minus (β^-) spectrum, along with Auger electrons (AEs), conversion electrons (CEs), and photon (X-ray and gamma-ray) emissions from ¹⁶¹Tb and ¹⁷⁷Lu radionuclides were considered for evaluating both self-cell and neighboring-cell effects.

The results indicate that for both self-cell and neighboring-cell effects,¹⁶¹Tb induces approximately 13% and 21% more DNA strand breaks than ¹⁷⁷Lu. Additionally, across all target-source configurations, electrons were the primary contributors to DNA damage, while photon emissions had the lowest impact.

The findings of present study highlight that ¹⁶¹Tb can be a better candidate than ¹⁷⁷Lu, particularly for treating the single and cluster tumor cells.