A method of evaluating a maximal dose deposited by an X-ray beam within a medium comprises the steps of: (a) irradiating said medium by said X-rays beam penetrating into a depth of said medium along an axis of said X-ray beam； (b) measuring a dose distribution along said axis. The step of measuring said dose distribution further comprises measuring cross-sectional distributions with a predetermined incremental shift thereof along said beam axis, and calculating a 1-dimensional function of said maximal dose in dependence on said depth taken from maximum dose at each cross-sectional distribution at each depth.
