Abstract: A method is for analyzing, using a detector of alpha particles, a sample comprising at least one radionuclide emitter of a plurality of alpha particles. The detector comprises a detection medium and a plurality of measurement cells suitable for measuring at least one incident signal generated by an interaction of the alpha particle with said detection medium. The detector is designed to provide an autoradiographic image of said sample. The method comprises a step for determining (E1) an initial energy of each alpha particle. The step comprises repeating three sub-steps: determining (D1) a position of a first interaction of an alpha particle with the detection medium, determining (D2) an energy deposited by the particle in the interior of the detector and determining (D3) the initial energy of the alpha particle. The method then comprises constructing an energy spectrum for one zone of the autoradiographic image.