High rate silicon tracker for proton computed tomography

Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements and in-situ positioning can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is saved by reconstructing the proton trajectory. We have developed a prototype system for proton CT and demonstrate a precise measurement of electron density and an improvement in spatial resolution. In order to control of the radiation dose and reduce the exposure time for imaging, the precise position detector should work with very high rate (a few MHz). We have developed high speed tracker with large area silicon strip detector, Amplifier-Shaper-Discriminator LSI, which was developed for drift chamber readout at high energy physics experiment, and FPGA. We report the performance of the tracker evaluated with very high intensity proton beam for the cancer therapy.