What effect does increasing filtration have on contrast?

Increasing filtration in radiography typically leads to a decrease in contrast. This is due to the fact that filtration removes low-energy photons from the x-ray beam. Low-energy photons contribute less to image formation, potentially increasing scatter radiation, which can lower the overall image contrast.

In radiographic imaging, contrast is the difference in density between different areas of the image. When low-energy photons are filtered out, the remaining high-energy photons are more likely to penetrate tissues effectively and produce a more uniform exposure, which can reduce the differences seen in the densities of the structures being imaged. As a result, the overall contrast decreases, making it more challenging to distinguish between different anatomical features.

This principle helps explain why, for instance, when using higher filtration, images may appear flatter and less defined, leading to a reduction in the visual distinction of structures that one might wish to identify more clearly.