CORRECTION OF COMPUTED-TOMOGRAPHY MOTION ARTIFACTS USING PIXEL-SPECIFIC BACK-PROJECTION

Cardiac and respiratory motion can cause artifacts in computed tomogra phy scans of the chest, We describe a new method for reducing these ar tifacts called pixel-specific back-projection (PSBP), PSBP reduces art ifacts caused by in-plane motion by reconstructing each pixel in a fra me of reference that moves with the in-plane motion in the volume bein g scanned, The motion of the frame of reference is specified by constr ucting maps that describe the motion of each pixel in the image at the time each projection was measured; these maps are based on measuremen ts of the in-plane motion. PSBP has been tested in computer simulation s and with volunteer data. In computer simulations, PSBP removed the s tructured artifacts caused by motion, In scans of two volunteers, PSBP reduced doubling and streaking in chest scans to a level that made th e images clinically useful, PSBP corrections of liver scans were less satisfactory because the motion of the liver is predominantly superior -inferior (S-I), PSBP uses a unique set of motion parameters to descri be the motion at each point in the chest as opposed to requiring that the motion be described by a single set of parameters, Therefore, PSBP may be more useful in correcting clinical scans than are other correc tion techniques previously described.