A radiograph produced using 6 mAs and 110 kVp needs to be repeated using a 16:1 ratio grid. What should the new mAs be?

When using a grid with a specific ratio, it's essential to understand how it influences the required technique to maintain image quality. A 16:1 grid ratio is highly efficient in reducing scatter radiation, which means that to achieve the same level of exposure on the image receptor as with an un-gridded exposure, you typically need to increase the milliampere-seconds (mAs).

In this scenario, when transitioning from a non-grid exposure at 6 mAs to a grid exposure, it is common practice to adjust the mAs to compensate for the additional filtration of scatter radiation by the grid. A 16:1 ratio grid requires an increase in mAs, commonly by a factor of approximately 4 to 5 times the original exposure.

When replacing the original 6 mAs with the new grid, multiplying by a factor of 1.5 to 2, while accommodating for practical adjustments and exposure consistency, results in a new mAs calculation approximately around 9 mAs. Thus, selecting 9 mAs ensures that the image retains the necessary exposure levels affected by the addition of the grid, achieving optimal diagnostic quality.

This approach aligns with radiographic principles regarding how grids work and the need for increased exposure when they are utilized.