Technical challenges and operational milestones in scaling proton beam current for tandem accelerator-based BNCT

High-current electrostatic tandem accelerators are considered a key technology for the development of compact hospital-based neutron sources for Boron Neutron Capture Therapy (BNCT). By employing charge-exchange stripping and SF 6 -gas insulation, these accelerator systems can efficiently generate 2.0–2.5 MeV proton beams for the 7 Li(p,n) reaction while maintaining a compact footprint. Although theoretical designs target beam currents of up to 10 mA to enable clinically practical treatment times, stable high-current operation remains a major technical challenge. As part of the staged development toward a full-scale accelerator system, the newly developed K-500 tandem accelerator at the Korea Institute of Radiological and Medical Sciences (KIRAMS) was successfully commissioned and its initial performance was evaluated. In this study, stable operation of a 500 keV proton beam under atmospheric conditions was demonstrated, achieving a maximum beam current of 7.3 mA. In addition, key technical limitations associated with high-current scaling were identified, and ongoing efforts toward achieving clinically relevant beam currents for accelerator-based BNCT (AB-BNCT) applications are discussed.