What is the formula to determine the grid ratio?

The grid ratio is a critical factor in radiographic techniques that affects image quality, particularly by enhancing contrast and reducing scatter radiation. The grid ratio is defined as the height of the lead strips divided by the distance between the strips. This measurement is vital because it illustrates how effectively the grid can absorb scatter radiation while allowing useful primary radiation to pass through to the detector.

The height of the lead strips represents how much material is available to absorb unwanted scatter, while the distance between the strips indicates how much primary radiation can travel through without being obstructed. A higher grid ratio generally leads to better image quality, as it increases the ability to differentiate between scattered and primary radiation.

The incorrect options reflect alternative calculations that do not accurately represent the grid ratio. For instance, considering scatter radiation or strip thickness in the formulation would misrepresent the relationship that defines the grid ratio, as these factors do not contribute directly to the basic calculation of height versus distance.