The Excillum MetalJet X-ray tube is a conventional microfocus tube with the solid-metal anode replaced by a liquid-metal jet. This type of anode is continuously regenerated and already in the molten stage. Thereby, the classical power limit of an X-ray source, when the anode is permanently damaged by the electron beam, may be disregarded. Especially in the microfocus X-ray spot size range, from about 5 µm diameter to a few tens of µm, a source based on a liquid-metal-jet anode significantly outperform a classical solid anode X-ray source