BNCT is biochemically targeted radiation therapy. Boron-10 (10B) atoms are selectively delivered to the tumor, followed by irradiation with epithermal neutrons (nth). A nuclear reaction occurs, when a 10B atom captures a neutron. The short range of the reaction products restricts most of the radiation dose to the boron-loaded cells.
The stable boron isotope 10B has a large neutron capture radius. Thus 10B is more likely to capture neutrons than many other elements that are present in biological environments (e.g. nitrogen and hydrogen). A fission reaction occurs upon neutron capture, and a lithium ion and an alpha particle are produced. These particles have high kinetic energies, but their range is only about 10 microns. This leads to very efficient cancer cell killing precisely at the site of boron accumulation.