| 摘要 |
<p>A scanning grid apparatus exhibiting high primary and low secondary X-Ray transmission of X-Ray radiation emitted from an X-Ray source defining a focal spot, including at least one scanning grid provided with top and bottom pairs of opposed grid slat retainers disposed in parallel planes. Pivotably attached between the top pair of retainers is a plurality of radiopaque linear or wavy grid slats separated at predetermined distances in the plane of the top pair of retainers. The bottom pair of retainers includes spacers for maintaining the grid slats separated predetermined distances within allowable limits in the plane of the bottom pair of retainers. The separation distances provided by the bottom pair of retainers is chosen as the geometric projection of the separation distances in the plane of the top pair of retainers from the source focal spot to the plane of the bottom pair of retainers, such that each of the grid slats is focused on the focal spot of the X-Ray source. The pairs of grid slat retainers are mechanically coupled to the source focal spot by means of a slotted linkage arm capable of moving the pairs of grid slat retainers linearly in the direction transverse to the plural grid slats to blur out and render invisible slat shadows which would otherwise appear on an image receptor, while nevertheless maintaining the grid slats focused on the source focal spot to reduce primary radiation cut-off. A pair of scanning grids in which the grid slat retainers of the respective grids are arranged orthogonally may be staggered between a subject and an X-ray image receptor to further suppress secondary radiation.</p> |
