The present invention relates to a system for X-ray imaging. It is explained to position (210) an X-ray detector 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 (220) by a processing unit in order to: operate (230) in a first imaging operation mode; or operate (240) in a second imaging operation mode; or operate (250) in the first imaging mode and in the second imaging mode; or operate (260) in 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 sensor array is associated with the first scintillator. The first sensor array comprises an array of sensor elements configured to detect optical photons generated in the first scintillator. The second sensor array is associated with the second scintillator. The second sensor array comprises an array of sensor elements configured to detect optical photons generated in the second scintillator. 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. The first scintillator has a thickness equal to or greater than 0.6mm. The second scintillator has a thickness equal to or greater than 1.1mm. In the first imaging operation mode the first scintillator and the first sensor array are configured to provide data useable to generate a low energy X-ray image. In the second imaging operation mode the second scintillator and the second sensor array are configured to provide data useable to generate a high energy X-ray image. In the third imaging operation mode the first scintillator, the first sensor array, the second scintillator and the second sensor array are configured to provide data useable to generate a combined energy X-ray image.