High spatial resolution radiation detectors, assemblies and methods including methods of making the radiation detectors and using the detectors in performing radiation detection. A radiation detector of the invention includes a substrate, a scintillator layer comprising a microcolumnar scintillator, and an optically transparent outer cover layer, the scintillator layer disposed between the substrate and the cover layer with a gap disposed between at least a portion of the cover layer and the scintillator layer.