A system for reconstructing a 3D volume has a surface acquisition system with a light source and an image sensor for characterizing the surface contour of a patient and an X-ray imaging system for acquiring X-ray projection data of the patient from a number of angular positions. A controller is programmed with instructions to synchronize the 3D surface contour characterization from the surface acquisition system with the acquired X-ray projection data. A processor executes a motion reduction method that uses the acquired X-ray projection data and the generated 3D surface contour characterization to reconstruct a 3D volume.