ARRT Practice Exam 2026 – All-in-One Guide to Master Your Radiologic Technologist Certification

Compton scatter is a phenomenon in radiation physics that occurs when a high-energy photon interacts with matter, specifically with an electron. In the context of the question, when a high-energy incident photon (not an electron, as mistakenly suggested) collides with an electron, it predominantly ejects an outer shell electron.

Outer shell electrons are more loosely bound to the nucleus compared to inner shell electrons, making them more susceptible to being ejected from their atomic orbit during such interactions. The energy from the incident photon is transferred to the outer shell electron, causing it to be ejected from the atom, while the photon itself is scattered at a different angle and energy level.

This interaction is significant in the field of radiologic technology because it helps to explain certain phenomena such as image contrast and radiation dose, as the scattering can affect how radiation interacts with tissues in diagnostic imaging.