An X-ray scanner

An X-ray scanner comprising: an X-ray source comprising a linear array of X-ray source points 802 and X-ray detection means comprising a linear array of detectors 804, wherein said linear arrays are preferably arranged substantially perpendicular to each other; and control means arranged to operate either said X-ray source points or said X-ray detectors in plurality of successive groupings. For example, the array of X-ray source points may be controlled to produce a plurality of successive illuminations, each illumination having a square wave pattern of a different wavelength (see Figs 14a-14c). The control means may apply a mathematical transform to the recorded readings from each of the array of detectors in order to reconstruct a three-dimensional image of an object being scanned. A number of electron sources suitable for use in said X-ray scanner are also disclosed (see Figures 1-4, 6-12 and 16-18).