There is provided an apparatus (100) for x-ray imaging comprising an x-ray source (10) and an x-ray detector (20) having a number of detector elements, wherein the x-ray source (10) and the x-ray detector (20) are arranged on a support that is able to rotate around a subject or object to be imaged to enable a set of projections at different view angles. The apparatus (100) is configured to operate the x-ray source (10) in switched kVp mode for alternately applying at least two different voltages, including a lower voltage and a higher voltage, during rotation to enable lower-energy and higher- energy exposures over the set of projections, thereby providing for lower-energy projections and higher-energy projections. The x-ray detector (20) is a photon-counting multi-bin detector configured to allocate photon counts to multiple energy bins, and the apparatus is configured to select counts from at least a subset of the energy bins to provide corresponding photon count information for both lower-energy projections and higher-energy projections. The apparatus (100) is configured to perform material basis decomposition for each of a number of the lower-energy projections and higher- energy projections and/or for each of a number of combinations of at least one lower- energy projection and at least one higher-energy projection, based on the corresponding photon count information.L'invention concerne un appareil (100) pour une imagerie par rayons X comprenant une source (10) de rayons X et un détecteur (20) de rayons X comportant un certain nombre d'éléments de détecteur, la source (10) de rayons X et le détecteur (20) de rayons X étant agencés sur un support qui est apte à tourner autour d'un sujet ou d'un objet à imager pour obtenir à un ensemble de projections à différents angles de vue. L'appareil (100) est conçu pour faire fonctionner la source (10) de rayons X en mode à kVp commuté pour appliquer en alternance au moins deux tensions différentes, comprenant une tension
