Which interaction results in the total absorption of an x-ray photon and contributes to image contrast?

The photoelectric effect is the interaction that leads to the complete absorption of an x-ray photon. During this process, an incident x-ray photon is completely absorbed by an inner-shell electron of an atom. This causes the electron to be ejected from the atom, resulting in the atom becoming ionized. The energy of the incident photon must be greater than the binding energy of the electron it displaces.

This effect is crucial for image contrast in radiographic imaging because it is more likely to occur in tissues with higher atomic numbers, such as bone. The differences in absorption between various tissues are what create the contrast in the image. Areas where more photoelectric interactions occur will appear lighter on the radiograph, while those with fewer interactions will appear darker. Consequently, the photoelectric effect plays a significant role in differentiating between various types of tissues, thus contributing to effective diagnostic imaging.

In contrast, the other interactions listed do not result in total absorption of the x-ray photon. The Compton effect involves the scattering of photons, which does not contribute to the same level of contrast, as some of the energy is retained in the scattered photon. Rayleigh scattering involves elastic scattering where the photon changes direction but not energy, and pair production, while it involves