Compact multispectral X-ray source

An X-radiation source can comprise an electron emission layer and an anode layer. In an embodiment the anode layer may be no more than approximately 1000 microns from the emission layer or include an anode region that laterally surrounds a hole extending through the anode layer. In one embodiment, a plurality of electron emission tips, extraction gate electrodes and anode regions may be used. When the anode regions comprise different materials, a plurality of wavelengths may be emitted. In another embodiment, a monolithic structure can be formed using processing operations similar to those used in conventional semiconductor device manufacturing. The X-radiation source can be relatively small and may have uses in applications with confined spaces, such as medical applications.