Which interaction primarily contributes to patient dose in radiographic imaging?

In radiographic imaging, the interaction that primarily contributes to patient dose is Compton scattering. This process occurs when x-ray photons interact with loosely bound outer-shell electrons in matter, resulting in the scattering of the photon and the ejection of the electron from its atom.

As x-ray photons pass through the body, a significant amount of energy is absorbed, and although some is transmitted for imaging, a portion is scattered back toward the patient or absorbed by neighboring tissues. This scattering contributes to the overall dose received by the patient because those photons that are not absorbed still impart energy to tissues. Particularly in diagnostic imaging where soft tissues are involved, Compton scattering is a significant factor because it happens more frequently than other interactions, especially for intermediate energy x-rays used in diagnostic procedures.

While other interactions like the photoelectric effect are indeed important for image contrast and can contribute to dose, they are more pronounced at lower energies and with heavier atomic materials. However, Compton scattering dominates in the energy ranges typically used in radiographic imaging and is thus the primary contributor to patient dose in these scenarios. Characteristic radiation and Bremsstrahlung radiation are more relevant to the production of the x-ray beam rather than its interaction with patient tissue.