Radiology Tech Physics Practice Test

After a Compton interaction, the atom is ionized and a vacancy is created in one of its electron shells. When an electron from a higher shell drops to fill that vacancy, the energy difference is released as a photon with a discrete energy specific to the element—that discrete emission is known as characteristic radiation. This is a hallmark of atomic structure: the emitted photon energies are fixed by the binding energies of the shells involved, giving a line-spectrum-like X-ray unique to the element.

This isn’t the same as the primary photon (the original beam) or the remnant transmitted photon, and it’s not primarily bremsstrahlung, which comes from the recoil electron decelerating in the nuclear field and yields a continuous spectrum.