The applicability of pions to cancer radiotherapy, 2

A theoretical analysis was attempted to give a remaining number of π meson, N(X), as function of depth X in a target, lucite as model, under a beam of π meson. Under the assumption of three different elementary processes, π-e Rutherford scattering, π-decay and π-nucleus interaction, N(X) was theoretically evaluated. It was shown that the estimated stopped points of π particles agreed well with the experimentally obtained data if the π-e Rutherford scatterings were the main cause of π momentum reduction. Since the decay of π meson is negligible in the reduction of π meson, N (X) is mainly due to π-nucleus reaction in the region of a small depth but it is due to π-nucleus Rutherford scattering at a point less than 1.5 cm before the stopped point of π. (author)