boron, gadolinium, and lithium neutron capture therapy: a multi-scale simulation by geant4 and geant4-dna toolkits

Boron neutron capture therapy (bnct) is an emerging targeted radiation therapy leveraging nuclear capture reactions to maximize tumor cell destruction with minimal damage to healthy tissues. given to clinical possible concentrations, attentions have recently been paid to 10b alternatives. this study presents a dosimetric comparison between bnct, gadolinium neutron capture therapy (gdnct) and lithium neutron capture therapy (linct) using the geant4 monte carlo toolkit, evaluating dose distributions and therapeutic gain across varying concentrations (1-50 ppm) of 10b, 157gd, and 6li in a snyder head phantom. furthermore, geant4-dna simulations were employed to quantify dna damage and predict cell survival via the two-lesion kinetic model. the results demonstrate that both bnct and linct, as alpha-emitters, achieve superior tumor dose enhancement and normal tissue sparing compared to gdnct. at 50 ppm, bnct and linct produced a 64-85% dose enhancement, outperforming gdnct by more than 20-fold. micro-scale analysis revealed that 10b and 6li induce a high proportion of complex, lethal dna double-strand breaks, leading to a steep, concentration-dependent decrease in cell survival. while 6li is identified as a potent and promising alternative alpha-emitter, 10b maintained a marginally higher biological effectiveness. this study not only confirms bnct's clinical superiority but also provides a rigorous framework for evaluating novel neutron-capture agents, underscoring the critical importance of radiation quality over neutron cross-section alone.