Proton Radiography Studies for Proton CT

We report the results of a beam experiment to develop proton computed tomography (pCT). The set-up consists of telescopes of silicon strip detectors at the entrance and exit of a phantom to predict the path of the proton within the phantom and of a crystal calorimeter to measure the proton energy loss with high precision. The energy loss permits calculating the integrated proton stopping power along each proton path from which the electron density distribution can be reconstructed. We describe the 2D-image reconstruction of a low-contrast phantom, derive the relationship between contrast, pixel size, and dose, and study the spatial resolution achievable with this set-up.