| 摘要 |
A radiographic imaging system ( 10 ) includes an array of detectors ( 16 ) arranged around a circular bore ( 18 ). A subject ( 14 ) is injected with a radioisotope. The subject ( 14 ), supported by a subject support means ( 12 ), is to be placed into the bore ( 18 ) for an examination. A fixed, non-circular shield ( 38 ) is rigidly mounted to one of an entrance ( 40 ) and an exit ( 42 ) of the bore ( 18 ) to prevent emission radiation originating outside of the bore ( 18 ) to reach the radiation detectors ( 16 ). The shield ( 38 ) extends from an outer periphery of the bore ( 18 ) toward and surrounding a central axis of the bore ( 18 ) and defines a fixed, non-circular subject receiving aperture ( 36 ). The shield ( 38 ) is tailored to a contour of the subject support and the subject ( 14 ) to permit the subject of a maximum girth to be received in the fixed, non-circular aperture ( 36 ).
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