Abstract
We propose protoacoustic radiography (PAR), an imaging modality combining proton excitation and acoustic detection for three-dimensional (3D) imaging from a single proton projection. PAR avoids the effect of multiple Coulomb scattering in imaging by detecting ultrasound. Proton-induced acoustic waves propagate spherically, enabling 3D imaging from a single projection. Additionally, the distinctive feature of proton beams-concentrating energy deposition primarily at the Bragg peak-allows for precise depth-selectivity through proton energy tuning. We performed PAR using clinical proton machines, and our results demonstrate the capability of PAR to reconstruct targets at various depths (between ∼20 and 23 cm) with an axial resolution of 1.3 mm by fully leveraging the Bragg peak and by tuning the kinetic energy of the proton beam. PAR offers opportunities for precise structural determination with protons both in biomedicine and nondestructive testing.