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.

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