What effect do radiographic grids have on contrast?

• A. Decrease contrast
• B. Increase contrast
• C. No effect on contrast
• D. Increases contrast by absorbing scatter radiation

Answer: (D)

The main idea is that radiographic grids boost image contrast by reducing the amount of scatter that reaches the image receptor. Scatter photons from the patient add a foggy, uniform signal that diminishes the differences between structures, making details harder to see. A grid sits between the patient and the detector and uses lead strips to absorb more scatter than primary radiation, so the photons that form the image are closer to the intended beam. This selective absorption sharpens edges and enhances the visibility of differences in tissue, increasing contrast.

It’s true that grids can absorb a small portion of primary photons too, which is why technologists often increase exposure (mAs) when using a grid to maintain the same receptor exposure. But the fundamental effect on image quality is the reduction of scatter, which yields higher contrast.