Abstract: A method and a data-processing system are disclosed for determining the proportion of calcium in coronary arteries using image data from CT angiography. In at least one embodiment of the method, anatomical landmarks are detected in the image data in the region of the heart and coronary arteries are segmented taking into account the detected landmarks. Regions with an increased HU value compared to a contrast agent surroundings are segmented in the segmented coronary arteries. A proportion of calcium respectively is calculated from the segmented regions for one or more of the segmented coronary arteries. At least the last two steps are carried out fully automatically by a data-processing system. Weighting factors for the individual regions are used when calculating the proportion of calcium, which weighting factors depend on both the threshold for segmenting the respective region and the volume of said region.

Abstract: A method and a CT system are disclosed for measuring the perfusion in vessels and/or muscles of the heart (cardiac perfusion) in a patient. In at least one embodiment of the method the patient receives a contrast agent bolus, the patient is scanned for a scan period of a plurality of cardiac cycles in a scan field of a CT system controlled by the cardiac rhythm, a plurality of CT image data is reconstructed from projection data of a particular cardiac phase from respectively one cardiac cycle, and the temporal profile of the absorption values at at least one location in the heart is determined and displayed on the basis of a plurality of CT image data at successive times.

Abstract: A reference body for alignment of laser projectors and an acquisition system of a tomography apparatus relative to one another, has at least two reference indicators, with each reference indicator establishing a reference plane. Each reference plane serves for alignment of one of the laser projectors. The at least two reference indicators enable the simultaneous alignment of laser projectors without a shifting of the reference body being necessary.