1. A method for creating a mass density image of an examination subject, comprising: generating radiation using a radiation source; X-raying the examination subject by the radiation; capturing attenuation images at a plurality of different energy levels by detecting the radiation; determining mass density values for a multi-dimensional mass density in the examination subject by inverting a multi-dimensional attenuation function by which the multi-dimensional mass density in the examination subject is a function of attenuation values of the attenuation images; and creating the mass density image from the attenuation images based on the determined mass density values, wherein a secondary radiation fraction caused by scatter is determined and the attenuation images are corrected in respect of the secondary radiation fraction to a primary attenuation fraction produced by attenuation, and wherein the secondary radiation fraction is determined in a correction image area that yields a same mass density when calculates the inverse attenuation function.