Patent ID: 7970097
Filing Date: 2011-06-28
Classification: A61B

Abstract:
1. A method for producing tomographic images, relating to different movement phases of a periodically moving object, via a tomography unit including at least one recording system arranged rotatably about a z-axis of the tomography unit, the at least one recording system including an X-ray tube to which a tube current is applicable and a detector to acquire projections, the method comprising: positioning the at least one recording system relative to the object at a first z-position along the z-axis; acquiring projections from a multiplicity of different projection directions at the first z-position in a fashion triggered by a movement signal representing movement of the object, projections relating to a first movement phase of the object being acquired in a prospectively defined first time window and projections relating to at least a second movement phase of the object being acquired in a prospectively defined second time window, the first movement phase and the second movement phase being in a same cycle of the object, an initial instant and a final instant relating to each of the time windows are prospectively determined taking account of at least one fluctuation parameter, the at least one fluctuation parameter characterizing an irregularity of the periodic movement of the object and a modulation of the tube current being performed in such a way that different values of the tube current are set in the first and the at least second time window to attain a prescribable different signal-to-noise ratio in produced images; sequentially positioning the recording system and respectively acquiring projections for at least the first and second movement phases in accordance with the positioning and acquiring steps at further z-positions along the z-axis until a prescribed examination area is scanned at the desired z-positions; and reconstructing, in real time or subsequent reconstruction, tomographic images on the basis of the acquired projections.