As photon energy increases, what generally happens?

As photon energy increases, penetration generally increases and tissue interactions decrease. This is primarily due to the relationship between photon energy and the interactions that photons have with matter. Higher energy photons have a greater ability to pass through tissues without being absorbed or scattered, which is why there is an increase in penetration.

When photon energy is low, there are more interactions with tissues, such as photoelectric effect and Compton scattering, which result in lower penetration. As the energy increases, the probability of these interactions decreases, allowing higher energy photons to penetrate deeper into materials or biological tissues. Consequently, at higher energy levels, while the ability to penetrate increases, the likelihood of interaction with the tissue diminishes. This concept is fundamental in radiographic imaging and radiation therapy, where understanding the balance between penetration and tissue interaction is crucial for optimal image quality and patient safety.