# Proton-Boron fusion reaction enhances proton radiobiology effectiveness.

Cirrone G.A.P., Mantib L. per la Collaborazione Proton-Boron

Relazione su invito
V - Biofisica e fisica medica
Aula 32C-2 - Lunedì 17 h 16:00 - 19:00
We exploited the ${}^{11}B(p,\alpha)2\alpha$ nuclear reaction to generate high-LET alpha particles with a clinical proton beam. To maximize the reaction rate, we used sodium borocaptate (BSH) with natural boron content. Boron-treated cells were irradiated at mid-SOBP (Spread Out Bragg Peak) depth and assayed for clonogenic survival and DNA damage induction. We recorded significantly increased cellular lethality and occurrence of chromosome aberrations. We proved that, if human cells are irradiated with a given amount of ${}^{11}B$, the interaction with protons results in an increase of almost a factor two in cell killing compared to boron-free irradiated controls. The findings suggest that the effect is due to the generation of low-energy, high LET alpha particles since we measured a marked increase in the complexity of DNA damage. The alphas produced have a sufficient range to come to a halt and release almost their entire energy in the cell nucleus by which severe damage is induced to the DNA, thereby enhancing the biological efficacy of the proton beam. Last results on the radiobiological effects of the p-B will be presented and a plan for the future activities dedicated to the complete and accurate investigation of the observed effects will be also discussed.