Which combination of exposure factors is likely to produce the shortest scale of contrast?

The combination of exposure factors that produces the shortest scale of contrast is determined primarily by the kilovoltage peak (kVp) setting and the grid ratio. A higher kVp results in increased penetration of X-rays, which tends to decrease the contrast of the image. In this case, both the kVp and grid ratio contribute to the contrast.

The option selected has a kVp of 70, which is relatively lower than the others. Lower kVp values typically result in higher contrast due to increased ionization and absorption differences between tissues. However, the quality of the image can be affected by the grid ratio; a 12:1 grid ratio enhances contrast by reducing scatter radiation, but it can also affect image quality if not used appropriately.

When considering all parameters in this option, the combination leads to a shorter scale of contrast, making it the most suitable choice. This is because a lower kVp contributes to higher variability in image density, resulting in a less extensive contrast range. Thus, using this combination of factors leads to an image with more pronounced differences in brightness, which is indicative of a shorter scale of contrast.

The other combinations involve either higher kVp values or varying mA and exposure times which can balance out the contrast differently, generally