Abstract: In an x-ray computed tomography system which acquire x-ray attenuation data using a fan beam of radiation, corrections for beam hardening are made by reprojecting the CT image data. The reprojection computations are reduced by rotating and warping the CT image data, and then performing a parallel reprojection along columns of data.

Abstract: An x-ray CT scanner acquires projection data from a series of projections during a scan of a patient's chest Movement of the patient's chest due to respiration is also sensed during the scan and this acquired motion data is employed along with an warping function which models chest motion to calculate factors which correct the acquired projection data and reduce motion artifacts in an image produced by back projecting the acquired projection data.

Abstract: A medical imaging system has a source of X-rays and a detector which produces an electrical signal in response to X-rays. A signal generated by the detector, during an acquisition interval, is used to construct an image of a medical patient, which may contain artifacts due to motion of patient. A signal is produced indicative of the motion, which has a quiescent period of minimum movement. A first portion of the signal is selected such that if image acquisition commenced at the end of the first portion, the acquisition interval would occur during a quiescent period. This first portion is initially used as a reference signal portion. Then subsequent portions of the signal are compared to the reference signal portion to produce a descriptor of the degree of similarity. An image acquisition is commenced when the descriptor indicates a given degree of similarity that is above a defined threshold.