What is the grid ratio of a grid with lead strips that are 4 mm high and spaced 0.5 mm apart?

To determine the grid ratio, you divide the height of the lead strips by the distance between the strips. In this case, with lead strips that are 4 mm high and spaced 0.5 mm apart, the calculation would be:

Grid Ratio = Height of Lead Strips / Distance Between Strips

Grid Ratio = 4 mm / 0.5 mm = 8

Thus, the grid ratio is 8:1. This indicates that for every unit of measurement (in this case, based on the distance between strips), there are eight units corresponding to the height of the lead strips. A higher grid ratio often means the grid is more effective at absorbing scattered radiation, which helps to improve the quality of the diagnostic images produced in radiography.