Image Quality

The image quality can be dramatically influenced by the choice of grid. A radiograph can be ruined using the wrong grid or using the grid in an incorrect manner.

Various Sizes

Grids are manufactured to accommodate all standard film sizes from 9x12 to 45x45 mm or 8"x10" to 18"x18". Customized grids to specifications are available upon request. Grids for use inside cassettes are 3 mm (1/8") smaller than the corresponding film size, whereas grids for use outside the cassettes are approximately 20 mm (1") larger than the corresponding film size. Extra large grids are made from two or more smaller sized grids that can be fitted together up to a maximum size of 49 cm x 49 cm (19"x19").

Focal Distance

The focal distance (f0) is the distance between the X-ray tube focal spot and the film. Each lead strip is aligned with the X-ray tube focal spot in a defined angle.
Depending on type of X-ray examination, different focal distances are required. Standard focal distances are 80, 100, 105, 115, 130, 140, 150 and 180 cm. Other focal distances can be made in a range from 40 cm up to infinity.
A parallel grid has = . ( =infinity)

Focal Range

Focal range is the distance interval in which an X-ray tube can be used with a certain grid. With lower ratio grids, the focal range is considerably wider, with a higher ratio, the range is narrower.