10:1 Ratio
178 LPI X-ray Grids, 10:1 Ratio.
Focused grids are used in case the location of the tube and the centering of the cassette are guaranteed, as for taking shots on a wall stand or a bucky.
The focused grids ensure a perfect homogeneity of optical density and contrast between the center of the image and the edges of the image.
It is recommended not to exceed the 10:1 ratio in order not to increase the patient dose unnecessarily