Feasibility of proton tomosynthesis in proton therapy

Currently, the patient dose of proton therapy and treatment planning arc based on the x-ray photon CT (computed tomography) data. However, material interactions between protons and photons arc different. Proton tomograms are useful to make with accuracy the dose calculations for planning and positioning of patients. For applying CT techniques, many projection images during at least half rotation are need. It makes extremely high patient dose. We apply the proton tomosynthesis, which is the limited angle tomography using proton-beams. The proton tomosynthesis may provide more accuracy of dose calculation and verifications with less patient dose. We describe the concept of the proton tomosynthesis and demonstrate its performance with GEANT4 simulation and experiments. We confirmed the feasibility of proton digital tomosynthesis through comparative analysis with the x-ray photon methods. This study is useful for proton therapy planning and verification.