| 摘要 |
A radiation detector or detector array which has a non-constant spatial response individually and in combination with a tomographic scanner. The detector has a first dimension which is oriented parallel to the plane of the scan circle in the scanner. Along the first dimension, the detector is most responsive to radiation received along a centered segment of the dimension and less responsive to radiation received along edge segments. This non-constant spatial response can be achieved in a detector comprised of a scintillation crystal and a photoelectric transducer. The scintillation crystal in one embodiment is composed of three crystals arranged in layers, with the center crystal having the greatest light conversion efficiency. In a preferred embodiment, the non-constant spatial response is achieved in a detector comprised of a single scintillation crystal whose response is shaped by inducing along said first dimension a scintillation conversion efficiency gradient. In the single crystal embodiment, the gradient is chosen so that the crystal has greater conversion efficiency centrally than peripherally.
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