In Compton interactions, which part of the atom does the incident x-ray photon interact with?

In Compton interactions, the incident x-ray photon primarily interacts with an outer-shell electron of an atom. This interaction occurs when the x-ray photon collides with an electron that is located in the outermost energy levels of an atom.

During this process, the x-ray photon transfers a portion of its energy to the outer-shell electron, which can then become ejected from the atom. As a result, the x-ray photon is scattered at a different angle with a lower energy than that of the incident photon. This interaction is significant because it demonstrates how x-ray photons can lose energy while ensuring the continuation of their path at a modified trajectory, which is an essential concept in radiology and radiation physics.

The interaction primarily with outer-shell electrons distinguishes it from other types of interactions like photoelectric absorption, where inner-shell electrons are involved. Therefore, understanding this mechanism is critical for interpreting the behavior of x-rays as they pass through matter and interact with tissues in medical imaging.