A system for reconstructing a 4D image has a surface acquisition system for generating a 3D surface model of an object and an X-ray imaging system for acquiring at least one 2D X-ray projection image of the object. A controller controls the surface acquisition system and the X-ray imaging system. A processor applies a 4D reconstruction algorithm/method to the 3D surface model and the at least one 2D X-ray projection to reconstruct a 4D X-ray volume of the imaged body part in motion.
