Tissue-composition-activated therapy: A Monte Carlo proof-of-concept for primary bone tumor treatment with lithium-6 ion beams

Exploring novel ion beams is an active research direction in medical physics. Lithium-6 (6Li), a weakly-bound nucleus, presents a unique opportunity for treating primary bone tumors by leveraging exothermic nuclear reactions with calcium in the bone microenvironment. This study employs high-statistics Geant4 Monte Carlo simulations to computationally evaluate the therapeutic potential of 6Li ion beams (600–1200 MeV, in 100 MeV steps). We reveal that 6Li ion beam irradiation of compact bone, compared to soft tissue, results in enhanced energy deposition (up to 5.984% at 1200 MeV) and a marked increase in deuteron production (up to 1.395%). This enhanced deuteron yield suggests a potential for localized deuterium enrichment, which, based on existing literature, imparts tumor-suppressive biological effects. Furthermore, the prominent 511 keV gamma peak observed underscores the inherent compatibility of this approach with positron emission tomography (PET) for treatment monitoring. Our findings establish 6Li ion as a unique therapeutic beam for bone tumor therapy. Leveraging its weakly bound nuclear structure, 6Li ion enables a dual-mechanism action that synergizes enhanced energy deposition with the in situ production of a tumor-suppressive agent (deuterium).