What are characteristic X-rays created from?

Characteristic X-rays are produced as a result of ionization of inner-shell electrons rather than outer-shell electrons. When an inner-shell electron is ejected from its atom due to the absorption of energy, typically from an incident photon, the atom becomes ionized. The vacancy created in the inner shell is then filled by an electron from a higher energy level, which results in the emission of an X-ray photon. This emitted photon has a specific energy that corresponds to the difference in energy between the two electron shells involved in the transition, which is characteristic of the specific element.

The process highlighted is essential to understanding X-ray production in various imaging modalities, including PET. Additionally, the energy of the characteristic X-ray is unique to each element, allowing for elemental identification based on the X-ray spectrum produced.

In contrast to this, the other processes mentioned are associated with different types of radiation or interactions. For example, Compton Scattering refers to the scattering of X-rays or gamma rays by free electrons, resulting in energy loss and changes in direction, while the Photoelectric Effect involves the complete absorption of a photon by an atom, leading to the ejection of an inner-shell electron, but does not generate characteristic X-rays. Bremsstrahlung Radiation, on the