A method for evaluating changes in the intensity of polychromatic radiation that is transmitted by a source having a known frequency spectrum (e.g. an X-band spectrum), and received by a sensor after having passed through a certain thickness of a body or sample consisting of one or more phases having a known composition, whereby artifact-related reconstruction errors may be corrected. The method is characterized in that the changes in intensity are evaluated by modeling the influences of a number of predetermined parameters related to the nature of each phase on the absorption coefficient of the body in one or more spectral bands of the polychromatic radiation. The method is useful for the tomographic analysis of geological samples or the human body.