Final answer:
X-ray photons are produced when electrons, ejected from a hot filament and accelerated by a high voltage, strike the anode of an X-ray tube, transferring energy to inner-shell electrons and resulting in the emission of X-ray photons.
Step-by-step explanation:
The primary source of X-ray photons from an X-ray tube is the process whereby electrons are accelerated and strike the anode material within the tube. Specifically, electrons are ejected from a hot filament due to thermal agitation in a vacuum tube. These electrons are then accelerated across a high-voltage potential, gaining kinetic energy from the electrical potential energy. Upon colliding with the anode, these energetic electrons convert their kinetic energy into various forms, one of which includes the emission of X-ray photons. This creation of X-ray photons is a result of the electrons interacting with the anode's atoms and transferring energy to the inner-shell electrons. Some of these inner-shell electrons are ejected, leading to the emission of X-ray photons when other electrons from higher shells fill these vacancies, releasing energy in the form of X-ray photons.