Speaker
Description
Beam-imaging methods in particle therapies are expected to eliminate deviations of the irradiation areas and to improve treatment results. Recently, we proposed a beam-imaging method by measuring secondary electron bremsstrahlung using imaging plates (IP) and confirmed that high-resolution therapeutic carbon-ion beam images could be acquired using an imaging device combining an IP and pinhole-type tungsten collimator. The purpose of this study is to evaluate the effect of a lead radiation shield on the range-estimation accuracy. Monte Carlo simulations were performed using PHITS. A carbon-ion beam was injected to a acrylic target. A tungsten collimator having a pinhole was placed at the distance of 31.2 cm from the beam. A lead radiation shield was placed on the tungsten collimator. To evaluate the effect of the lead radiation shield, simulations were repeated with changing the thickness of the radiation shield. We found that the noise component in the acquired image decreased and the accuracy improved with increasing the thickness of the radiation shield.
