Described is a self-contained, small, lightweight, power-efficient and radiation-shielded module that includes a miniature vacuum X-ray tube emitting X-rays of a controlled intensity and defined spectrum. Feedback control circuits are used to monitor and maintain the beam current and voltage. The X-ray tube, high-voltage power supply, and the resonant converter are encapsulated in a solid high-voltage insulating material. The module can be configured into complex geometries and can be powered by commercially available small, compact, low-voltage batteries.