Boron Neutron Capture Therapy of Malignant Melanoma Using 10B-Paraboronophenylalanine with Special Reference to Evaluation of Radiation Dose and Damage to the Normal Skin

A treatment regimen for boron neutron capture therapy of malignant melanomas is described using ${}^{10}{\rm B}\text{-paraboronophenylalanine}$ as the tumor-targeting compound. As a therapeutic dose, we adopted the maximum tolerable dose for the skin regardless of tumor10 B concentration. In practice, the maximum neutron fluence should be decided prior to starting irradiation. For this purpose, the kinetics of the concentration of10 B in the blood and skin and the skin-to-blood ratios were analyzed in the six patients who received 170 mg/kg of the compound intravenously, and skin concentrations during irradiation were predicted using a standard skin factor curve. This yields a skin concentration at time T based on the blood concentration at time 0. We calculated the maximum tolerable fluence yielding but not exceeding 18 RBE-Gy by assuming that the RBE of ${}^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ and ${}^{10}{\rm B}({\rm n},\alpha)^{7}{\rm Li}$ reaction for skin damage is 2.5. Actual skin reactions ...