A system for Time-of-Flight tomography includes an x-ray source capable of producing pulsed x-rays with a pulse duration of about 100 ps or faster, a single-photon detector configured to detect individual photons backscattered from an object when present and illuminated by the x-ray source, the single-photon detector producing a two-dimensional image, and a processor for determining a Time-of-Flight of an individual photon from the x-ray source and backscattered by the object to the single-photon detector. Operating the system pulsing at 100 picosecond or faster, pulsing the x-ray source at least once to illuminate at least part of an object, detecting via a detector one or more individual backscattered photons from the object, and determining a length of time for an individual backscattered photon to travel from the x-ray source to the photon detector.
