| 摘要 |
PROBLEM TO BE SOLVED: To change, for example, the position of a lighting field arbitrarily by providing a fluorescent layer on one surface and a photoelectric conversion means on the other surface of a flat-plate-shaped shading means for prescribing the lighting field where a shading region can be changed by an electrical signal from the outside. SOLUTION: An electrode of a vapor deposition layer made of, for example, aluminum is provided on the surface of a substrate 1 that is made of, for example, polyimide film and an amorphous semiconductor layer 2 is formed on it. The amorphous semiconductor layer 2 is created by mixing a doped agent into, for example, Si, AsGa, and Ge or is in PIN structure using the mixtures and compounds. A transparent electrode 3 is provided on the upper surface. A liquid crystal mask 4 is provided at the side of the transparent electrode 3 and a fluorescent body layer 5 is provided on the upper surface, thus constituting an X-ray detector D. The fluorescent body layer 5 is arranged on the rear surface of an X-ray film opposingly, X rays through a subject is converted to light by the fluorescent body layer 5, and light is passed through the lighting field of the liquid crystal mask 4 and is converted to an electrical signal before being fed to an X-ray automatic exposure controller, thus enabling the lighting field of the liquid crystal mask 4 to be variable and to be set arbitrarily.
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