Computer tomagraphy method with helicoidal scanning of an examination area

A computer tomography method which involves helical scanning of an examination zone by means of a scanning unit which includes a radiation source (S) and a detector unit (16), an object present in the examination zone (13) and the scanning unit simultaneously rotating about an axis of rotation relative to one another and performing a motion parallel to the direction of the axis of rotation, resulting in a relative motion in the form of a helix (17), and also involves a reconstruction of the spatial distribution of the absorption within the examination zone from the measuring data acquired by the detector unit, characterized in that it includes the following steps

• a) using exclusively the measuring data for the reconstruction which are obtained from rays which pass exactly through the area between two adjacent turns of the helix, the points within the examination zone thereby being irradiated over an angular range of exactly 180 degrees—as seen from the point itself,
• b) rebinning the measuring data and the associated rays so as to form a number of groups, each group comprising a plurality of planes which extend parallel to the axis of rotation and each of which contains a respective fan beam,
• c) filtering the data of each group, formed by the rebinning,
• d) reconstructing the spatial distribution of the absorption from the filtered data of different groups.