Computed tomography device comprising an x-ray source and an x-ray
detecting unit. The x-ray source comprises a cathode with a plurality of
individually programmable electron emitting units that each emit an
electron upon an application of an electric field, an anode target that
emits an x-ray upon impact by the emitted electron, and a collimator.
Each electron emitting unit includes an electron field emitting material.
The electron field emitting material includes a nanostructured material
or a plurality of nanotubes or a plurality of nanowires. Computed
tomography methods are also provided.