Computerized tomography method with helical relative movement and conical beam

A computerized tomography method having the steps:

• a) generation with a radiation source of a conical beam passing through an examination area and an object located therein,
• b) production of relative movement between the radiation source on the one hand and the examination area on the other, which comprises rotation about an axis of rotation and displacement parallel to the axis of rotation and takes the form of a helix, wherein the position of the radiation source on the helix is defined by an angular position,
• c) acquisition of measured values with a detector unit during the relative moment, whereby the measured values depend on the intensity in the beam on the other side of the examination area and the detector unit comprises a detector surface,
• d) reconstruction of a CT image of the examination area from the measured values, wherein an exact or quasi-exact, filtered 3D back-projection with redundant measured values is performed according to the following steps:
• determination of the partial derivative of measured values from parallel rays with different radiation source positions depending on the angular position of the radiation source on the helix,
• filtering of the derived measured values along filter lines, wherein a plurality of filter lines are assigned to at least some of the measured values, such that these measured values are filtered several times,
• reconstruction of the absorption distribution at locations to be reconstructed in the examination area by back-projection of the measured values.