A Method for Calculating the Absorbed Dose near Interface from <tex-math>${}^{10}{\rm B}(n,\alpha){}^{7}{\rm Li}$</tex-math> Reaction

A simplified method is presented for calculating the absorbed dose delivered from the <tex-math>${}^{10}{\rm B}(n,\alpha){}^{7}{\rm Li}$</tex-math> reaction by thermal neutron in medium near the interface of a boron-containing region and a boron-free one. The method takes into account the contribution of the recoiled lithium particle to the absorbed dose and the variation of LET with charged particle energy. Using "combined LET" values derived from the LET of alpha particle and lithium recoil, so-called geometrical factors for calculating the absorbed dose for plane, spherical, and cylindrical interfaces are presented. The geometrical factor for the cylindrical interface is applied to estimate the absorbed dose in the cerebral vascular wall in the boron neutron-capture therapy of brain tumors in man.