What is the term for the total absorption of an x-ray photon by an atom of the body part?

The correct term for the total absorption of an x-ray photon by an atom in the body is known as the photoelectric effect. This process occurs when the energy of an incoming x-ray photon is completely absorbed by an inner-shell electron of an atom. As a result, this electron is ejected from the atom, leading to ionization. The energy of the photon is transferred to the electron, which must have enough energy to overcome its binding energy and escape from the atom.

The significance of the photoelectric effect lies in its role in diagnostic imaging, as it contributes to the contrast of images produced, especially in tissues with high atomic numbers, such as bone. When x-ray photons are absorbed, they do not contribute to the image, allowing the surrounding tissues to be visualized more clearly against the areas where absorption occurs.

Contrast this with the other processes: Rayleigh scattering involves the elastic scattering of x-ray photons without any energy transfer, while the Compton effect refers to the inelastic scattering of x-ray photons, resulting in partial absorption and the loss of energy to an outer-shell electron. Pair production occurs at much higher photon energies and involves the creation of an electron-positron pair rather than the total absorption of the photon.