An X-ray detector is positioned relative to an X-ray source such that at least a part of a region between the X-ray source and the X-ray detector is an examination region for accommodating an object. The X-ray source and X-ray detector are controlled by a processing unit in order to operate in a first imaging operation mode, a second imaging operation mode, and/or a third imaging operation mode. The detector comprises a first scintillator, a second scintillator, a first sensor array, and a second sensor array. The first scintillator is disposed over the second scintillator such that X-rays emitted from the X-ray source first encounter the first scintillator and then encounter the second scintillator.