What is the grid density parameter of the grid equipped with bucky stand?

What is the grid density parameter of the grid equipped with bucky stand? Usually, the bucky stand is now used to place flat panel detectors. If it is a grid configured for flat panel detectors, then only conventional parameters are required. For example: 18*18 inches, 10:1, 40L/cm, 1.8m
A brief introduction to the grid: the grid should be placed between the human body and the film, it can filter most of the scattered rays, only a small part of the scattered rays leak.
The structure of the grid and the specifications of the grid: The grid has the following three main technical parameters:
Focal length: the vertical distance from the convergence line of the lead strip to the surface of the grid, f
Grid ratio: It is also a grid ratio, which is the ratio of the lead bar height to the lead bar gap, R
Grid density: the number of lead bars within a unit distance, N

Author：Lillian