3. (30 pts) a) Find the ratio of the probability of photoelectric interaction) for the following 2 cases: (Probability of case1/ Probability of case2) case 1: atomic number is 2z, photon energy is 3E, case2: atomic number is Z, photon energy is 0.75E. b) Why does the image contrast decrease if we increase the x-ray energies in the imaging process? Consider the photoelectric interaction in your answer. c) Which parameters affect Compton scatter linear attenuation coefficient? Which parameter has a dominant effect on this coefficient when we consider the difference between soft tissue and adipose tissue