Medical imaging devices using low-dose X or gamma ionizing radiation

Medical imaging device using X or gamma ionizing radiation, comprising a source of ionizing radiation in a divergent beam, a longitudinal slit forming a diaphragm making it possible to deliver a sheet-form illumination beam distributed substantially in a plane containing the longitudinal slit, and means for detecting a beam transmitted by a body to be observed, illuminated by the sheet-form illumination beam, characterized in that said detection means comprise a drift chamber and a multiwire chamber which are filled with a gas making it possible to generate electrons, said chambers comprising, arranged in a direction orthogonal to the plane containing the slit and the sheet-form illumination beam:

• a drift space for the electrons, comprising a first cathode electrode, and an ionizing-ray/electron converter consisting of a multichannel mechanical structure,
• an electron proportional multiplier anode for generating multiplied electrons and corresponding ions,
• a second cathode electrode, placed in the vicinity of the multiplier anode, said multiplier anode and the second cathode electrode consisting of conductor elements extending in two planes parallel to that of the sheet-form illumination beam, along substantially orthogonal directions, in order to permit two-dimensional localization of the electrons in this plane.