1. A gamma-ray imaging device, comprising: a scintillator which converts gamma rays into localized flashes of light; an image intensifier that collects a substantial fraction of the light from each flash produced by a single gamma-ray photon and produces an amplified flash of light; an optical system including a video camera to image each amplified flash onto an imaging detector that operates at a frame rate fast enough to allow spatial separation of most of the clusters of pixels that receive light from different gamma-ray interactions in the scintillator; and a processing unit programmed with instructions, the instructions when executed identify the clusters of pixels on the video camera associated with respective amplified flashes of individual gamma-ray photons and use the data from said cluster of pixels to perform a statistical estimation of a position where the corresponding gamma-ray photon interacted with the scintillator and the energy deposited in the interaction.