Every X-ray exposure will contain photons produced from which interactions?

The presence of photons in every X-ray exposure is primarily due to bremsstrahlung interactions. Bremsstrahlung, which means "braking radiation" in German, occurs when high-speed electrons are decelerated or deflected by the electric fields of atomic nuclei. This interaction results in the production of X-ray photons across a broad spectrum of energies.

In the context of X-ray production, when electrons from a cathode strike a target material (such as tungsten in an X-ray tube), a significant portion of the energy from these electrons is converted into X-ray photons through bremsstrahlung. This process is responsible for the majority of the X-rays produced in most radiographic systems.

While characteristic radiation and other interactions such as elastic scattering and the photoelectric effect may play roles in certain scenarios, they do not account for the direct production of X-ray photons resulting from the interactions occurring within the X-ray tube during exposure. Characteristic radiation only happens when electrons transition between specific energy levels in the target, producing X-rays at discrete energies. Elastic scattering involves the change in direction of photons without energy loss, but it does not generate new X-ray photons. The photoelectric effect describes the absorption of X-ray photons by matter rather than their production.