An efficient method of randomly sampling the coherent angular scatter distribution

Monte Carlo simulations of photon transport phenomena require random selection of an interaction process at each collision site along the photon track. The possible choices are usually limited to photoelectric absorption and incoherent scatter as approximated by the Klein-Nishina distribution. Coherent scattering events are usually ignored. One reason for this omission is the lack of documentation in the medical physics literature concerning an efficient and accurate procedure for sampling the coherent angular scatter distribution. The authors describe a technique to accomplish this task. Although similar methods have been described elsewhere (Cashwell et al. 1973, Chan 1981), the authors feel this technique should be made more easily available to the medical physics community.