Abstract: A medical imaging system includes an x-ray source (112) having a focal spot that emits radiation that traverses an examination region (108). The position of the focal spot along a longitudinal direction is a function of a temperature of one or more x-ray source components. The system further includes a detector (120) that detects the radiation and a collimator (116), disposed between the x-ray source (112) and the examination region (108), that collimates that radiation along the longitudinal direction. A focal spot position estimator (132) dynamically computes an estimated position of the focal spot along the longitudinal direction based on the temperature of one or more x-ray source components. A collimator positioner (128) positions the collimator (116) along the longitudinal direction based on the estimated focal spot position prior to performing a scan.

Abstract: A medical imaging system includes an x-ray source (112) having a focal spot that emits radiation that traverses a examination region (108). The position of the focal spot along a longitudinal direction is a function of a temperature of one or more x-ray source components. The system further includes a detector (120) that detects the radiation and a collimator (116), disposed between the x-ray source (112) and the examination region (108), that collimates that radiation along the longitudinal direction. A focal spot position estimator (132) dynamically computes an estimated position of the focal spot along the longitudinal direction based on the temperature of one or more x-ray source components. A collimator positioner (128) positions the collimator (116) along the longitudinal direction based on the estimated focal spot position prior to performing a scan.

Abstract: A three dimensional (3D) magnetic resonance imaging (MRI) system (100) performs object-induced geometric distortion correction. The MRI system performs (202) a 3D MRI pulse sequence to acquire a first 3D MR image of an examination region containing at least a portion of a subject and performs (202) the 3D MRI pulse sequence a second time to acquire a second 3D MR image of the examination region A computer system (110) computes (210) a voxel error map based on a phase difference between the first and second 3D MR images and corrects (212) voxel positions in one of the 3D MR images in accordance with the voxel error map.