Which of the following grids would have a higher grid factor and therefore a high mAs?

A grid is used in radiography to improve the contrast of images by absorbing scatter radiation that can degrade image quality. The grid factor refers to the increase in mAs (milliampere-seconds) needed when using a grid compared to not using one. Higher grid ratios are more effective at reducing scatter radiation, which means they require more mAs to compensate for the additional radiation absorbed by the grid.

In this context, the grid with a 16:1 ratio is the highest among the choices provided. This high ratio means that the grid is very effective at improving image quality by filtering out scatter more than lower ratios. Consequently, to achieve optimal exposure and maintain image quality when using this higher ratio grid, a significantly greater amount of mAs is necessary.

As the grid ratio decreases, the effectiveness in absorbing scatter radiation also decreases, which means that less mAs is required for adequate image quality. Therefore, grids with lower ratios, such as 6:1, 8:1, and 12:1, would necessitate less mAs compared to the 16:1 grid. Hence, the option indicating the 16:1 ratio correctly identifies the grid requiring the highest mAs due to its high grid factor.