X-ray computed tomography 3D reconstruction requires through-thickness information from different views (conventional methods would require hundreds of views). Therefore, the tomography imaging experiment involves radiographic scanning around a sample by fixing the X-ray source and detector and rotating the sample at a constant altitude around the central axis. To represent spatial location of X-ray beams from different imaging direction, we encode the projection direction into Cartesian coordinate system. We sample points along the 0 deg projection beam as a reference coordinate (x 0 , y 0 , z 0 ), and rotate the X-ray parallel beams in the reverse direction of the sample rotation. For a field of view of w × w, the reference point (x 0 , y 0 , z 0 ) on X-ray parallel beams rotates angle θ around the central vertical axis (i.e., y-axis) where (x c , y c ) = (w/2, w/2) will be (x 1 , y 1 , z 0 ). Here,