Which of the major interactions between x-ray photons and tissue cells is most likely to occur with tissues having high atomic number?

Which of the major interactions between x-ray photons and tissue cells is most likely to occur with tissues having high atomic number?

• A. Compton scatter
• B. Photoelectric effect
• C. Rayleigh scatter
• D. Transmission

Answer: (B)

The photoelectric effect is the major interaction between x-ray photons and tissue cells that is most likely to occur in tissues with high atomic numbers. This phenomenon is characterized by the complete absorption of the x-ray photon when it interacts with an inner-shell electron of an atom. When the photon has sufficient energy, it can eject this electron, resulting in ionization of the tissue.

Tissues with high atomic numbers, such as bone, have a greater likelihood of undergoing the photoelectric effect because the probability of this interaction increases with the atomic number of the absorbing material. The higher the atomic number, the more tightly bound the inner-shell electrons are to the nucleus, making it more likely for the incoming x-ray photon to be absorbed instead of scattering or passing through the material.

In contrast, interactions like Compton scatter and Rayleigh scatter occur more frequently with lower atomic number tissues or do not involve energy absorption to the same extent. Transmission simply refers to the photon passing through the tissue without interaction. Therefore, the photoelectric effect is the predominant interaction in high atomic number tissues, making it the correct answer to this question.