X-ray image signal generator

This patent claim on behalf of EMI Ltd. relates to a detector arrangement which responds to a pattern of X-radiation emergent from a body under examination to generate electricl signals indicative of the spatial variation of the X-radiation forming the pattern. The arrangement includes a box containing a noble gas e.g. xenon, under pressure and having an entrance window exposed to the radiation pattern. Opposite which is a back-plate including a sheet of charge-retaining electro-optic material which communicates with the gas and a pattern of electrical charge, corresponding to the pattern of radiation, is built up thereon. The material is interrogated, to generate the electrical signals indicative of the charge pattern, by means of a laser beam which is scanned over the material and detected by a suitable device, the electro-optic material being, for example, a liquid crystal, a material whose dimensions change in response to electric charge or one which induces rotation of the plane of polarisation of an incident light beam. (author)