| 摘要 |
PURPOSE:To expand a detection width of multilayer detector rings in the layer direction as required by shifting the multilayer detector rings in the layer direction until the whole of the necessary detection width can be covered in the layer direction. CONSTITUTION:In the case when detector rings 1 to 4 of four layers are provided and a gap between the adjacent ones of the detector rings 1 to 4 in the layer direction Z is D, the detector rings 1 to 4 are disposed at positions in the direction Z indicated by a solid line and the collection of data in slices positioned at Z1 to Z7 is executed by a scan on the occasion. When the detector rings 1 to 4 are shifted by D/4 as a whole in the direction Z, subsequently, the collection of data in seven slices at positions shifted by D/4 from Z1 to Z7 respectively can be executed. Data in slices at Z2 to Z8 are collected by making a shift further by D/4, and data in slices at positions shifted by D/4 from Z2 to Z8 are collected by making a shift by D/4 again. By this method, a detection width in the direction Z can be expanded to 3X3/4D.
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