How to avoid the x ray grid of focal point and focal length

The deviation of x ray grid center should be avoided as far as possible. In the case of static x ray grid, there should be no deviation; when using movable x ray grid, there will inevitably be center deviation, but the deviation should be designed as small as possible.

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In some cases, the distance from the focus to the cartridge needs to be changed according to the different parts of the illuminated area, but the x ray grid can not be replaced frequently, so only a permissible change of focal length can be stipulated. When the primary ray transmittance at the edge of the effective area of the x ray grid decreases by 40%, the film distance at this time is generally stipulated as the limit value. The change should not be greater than or less than 25% of the filter focal length. Therefore, the focal length indicated on the x ray grid is nominal, and the practical focal length can be used in a certain range.

Author：X Ray Grids Maker