Which X-ray interaction with matter predominates in soft tissue above 80 kVp?

In the context of X-ray interactions with matter, particularly concerning soft tissue at energies greater than 80 kVp, Compton scattering is the predominant interaction. Compton scattering occurs when an X-ray photon collides with a loosely bound outer shell electron of an atom, resulting in the ejection of that electron and a transfer of energy to the photon.

At higher energies, like those above 80 kVp, the likelihood of Compton interactions increases significantly compared to other types of interactions. This is due to the fact that the probability of photoelectric absorption, which is dependent on the energy of the incident photon and the atomic number of the absorbing material, decreases in soft tissue as energy increases. Consequently, for X-ray energies in this range, Compton scattering becomes more prevalent, especially in materials like soft tissue that have relatively low atomic numbers.

Additionally, while pair production does occur at energies over 1.022 MeV, it is not relevant at the 80 kVp range. Classical scattering, or coherent scattering, is negligible for diagnostic X-ray energies, especially in tissues. This further underscores why Compton scattering is the correct choice in this scenario.