The present invention relates to an imaging apparatus for generating an image of a region of interest of an object. The imaging apparatus comprises a radiation source (2) for emitting radiation (4) and a detector (6) for measuring the radiation (4) after having traversed the region of interest and for generating measured detection values depending on the measured radiation (4). The imaging apparatus further comprises an attenuation element for attenuating the radiation (4) before traversing the region of interest and an attenuation element scatter values providing unit (12) for providing attenuation element scatter values, which depend on scattering of the radiation (4) caused by the attenuation element. A detection values correction unit (17) corrects the measured detection values based on the provided attenuation element scatter values, and a reconstruction unit (18) reconstructs an image of the region of interest from the corrected detection values.