| 摘要 |
Film changers used in biplane radiography are provided with shields having radiolucent and radiopaque sections which are alternately disposed in front of the x-ray film presented by the film changers for exposure. Operation of the two shields is synchronized to dispose the radiopaque portion of one shield in front of one changer when the radiolucent portion of the other shield is disposed in front of the other changer such that scattered radiation cannot reach film in the one changer and fog it when an image is being recorded by the other changer. In one disclosed embodiment of the invention, the shield is a flexible endless belt with alternating radiopaque and radiolucent sections mounted for rotation in a loop around the film changer. In a second disclosed embodiment of the invention, planar discs having alternating radiopaque and radiolucent sectors are rotated in front of the film changers. In yet another embodiment of the invention, planar members, each having one radiopaque and one radiolucent section, are mounted for reciprocal movement in front of the film changers.
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