X-ray computed tomography (CT) was developed in the 1960s and early 1970s as a method of producing transverse tomographic (cross-sectional) images of the human body. Images are calculated from a large number of measurements made of X-ray transmission through the body within a specified plane. Several methods of reconstructing CT images have been proposed and described by many authors, including iterative algebraic techniques, the direct Fourier transform technique, and convolution-backprojection. 3-D reconstructions have been used to assist in distinguishing motion artifacts from physical dissections in the descending aorta. Most methods require a simple model of organ motion, such as a translational, rotational, or linear expansion. The problem of motion artifacts has been addressed in other types of real-time imaging systems such as radar satellites and sonars. It was found that application of synthetic aperture processing increases the resolution of a phased array imaging system as well as corrects for the effects of motion.