A computed tomography system for generating an image of a subject comprising a contrast agent, the computed tomography system comprising: - a projections providing unit for providing several sets of spectral projections of the subject, wherein the several sets of projections have been acquired by detecting radiation, which has been emitted by a radiation source and which has traversed the subject, on a detection surface of a detector, while the radiation source and the subject have rotated relative to each other around a rotation axis, wherein different sets of spectral projections correspond to different positions of the radiation source along the rotation axis, - a decomposition unit for decomposing the spectral projections into first projections being indicative of the contrast agent within the subject and second projections not being indicative of the contrast agent within the subject, - an image generation unit for generating the image by (a) determining for each first projection a contrast value being indicative of a total amount of contrast agent based on projection values of the respective first projection acquired within a respective region of interest on the detection surface and scaling the first projections such that for different first projections of a same set the same contrast value is determined, and reconstructing an image based on the scaled first projections and (b) reconstructing for the different sets first images based on the respective first projections, wherein the first images of the different sets partly overlap in overlap regions, scaling the first images of the different sets such that overlapping first images of the different sets have a same intensity in the respective overlap region with respect to a predefined similarity measure and combining the scaled first images for generating the image. - a projections providing unit for providing several sets of spectral projections of the subject, wherein the several sets of projections have been acquired by detecting radiation, which has been emitted by a radiation source and which has traversed the subject, on a detection surface of a detector, while the radiation source and the subject have rotated relative to each other around a rotation axis, wherein different sets of spectral projections correspond to different positions of the radiation source along the rotation axis, - a decomposition unit for decomposing the spectral projections into first projections being indicative of the contrast agent within the subject and second projections not being indicative of the contrast agent within the subject, - an image generation unit for generating the image by (a) determining for each first projection a contrast value being indicative of a total amount of contrast agent based on projection values of the respective first projection acquired within a respective region of interest on the detection surface and scaling the first projections such that for different first projections of a same set the same contrast value is determined, and reconstructing an image based on the scaled first projections and (b) reconstructing for the different sets first images based on the respective first projections, wherein the first images of the different sets partly overlap in overlap regions, scaling the first images of the different sets such that overlapping first images of the different sets have a same intensity in the respective overlap region with respect to a predefined similarity measure and combining the scaled first images for generating the image.