Beam range estimation by measuring bremsstrahlung

Abstract

We describe a new method for estimating the beam range in heavy-ion radiation therapy by measuring the ion beam bremsstrahlung. We experimentally confirm that the secondary electron bremsstrahlung process provides the dominant bremsstrahlung contribution. A Monte Carlo simulation shows that the number of background photons from annihilation gamma rays is about 1% of the bremsstrahlung strength in the low-energy region used in our estimation (63–68 keV). Agreement between the experimental results and the theoretical prediction for the characteristic shape of the bremsstrahlung spectrum validates the effectiveness of our new method in estimating the ion beam range.