Proton computed tomography with a 250 MeV pulsed beam

Proton computed tomography (CT) has been performed using a 250 MeV pulsed beam. We developed a multiple-pencil-beam scanning method using a combination of moving slits for a reduction of the beam-scanning time. A magnetic spectrometer was used to measure the average energies of pulsed protons precisely. Position detectors have been developed to measure the centers-of-gravity of the multiple pencil beams at the image plane of the spectrometer. We obtained a 2-dimensional distribution of electron densities in a specimen within eight minutes by the method. We found that accurate information of the electron density was obtained by the method and that the density resolution was comparable with that of conventional X-ray CT. (orig.)