If the SID is decreased and an 8:1 grid is added, what would be the expected change in mAs?

When the source-to-image distance (SID) is decreased, the primary effect is an increase in the intensity of the radiation reaching the image receptor because the x-rays are closer to the target. However, adding an 8:1 grid introduces a factor that requires more mAs (milliampere-seconds) to achieve the same level of image density since grids absorb a portion of the x-rays to reduce scatter.

The combination of decreasing the SID, which would typically reduce the necessary exposure, and adding a grid, which necessitates an increase in exposure due to its attenuation of x-rays, leads to an overall increase in the required mAs. The grid's design and its ratio (in this case, 8:1) play a significant role in determining how much additional mAs is required to maintain image quality.

Thus, while reducing SID alone might lower the exposure needed, the presence of the grid means that the mAs must be increased to compensate for the loss of transmitted x-rays, resulting in an expected increase in mAs when these two factors are combined.