This invention provides an X-ray CT image processing method that allows more flexible expression by expressing X-ray absorption coefficients probabilistically, makes it possible to acquire reconstructed images that are comparable to those obtained by conventional methods but involve lower X-ray doses, and can reduce beam-hardening artifacts. A probability distribution for the observation of projected X-rays is set and statistical inference is performed. Said probability distribution is expressed in terms of the process of observing a multiple-X-ray sum resulting from multiple projected X-rays being incident upon a detector. Said multiple-X-ray sum is expressed in terms of a plurality of X-rays with different wavelengths and spatial positions and directions being incident upon the detector as a result of the fact that the X-ray detection surface of the detector is not a single point in space but rather has a given area, the fact that the X-ray detection period of the detector is not a single instant but rather has a given duration, and the fact that the spectral distribution of the X-rays is not a line spectrum but rather has a given spread. Bayesian inference in which the expected value of the posterior distribution is used for statistical inference is performed on the basis of a prior distribution for X-ray absorption coefficients, said prior distribution having parameters for the material and the observation process in terms of which the multiple-X-ray sum is expressed.La présente invention concerne un procédé de traitement dimage de tomodensitométrie (CT) à rayons X qui permet une expression plus flexible en exprimant des coefficients dabsorption de rayons X de manière probabiliste, permet dacquérir des images reconstruites qui sont comparables à celles obtenues par des procédés classiques mais impliquent des doses de rayons X plus faibles, et peut réduire les artéfacts de durcissement de faisceau. Une distribution de probabilités pour lobservation de rayons X pr
