Computed tomography method and apparatus for acquiring images dependent on a time curve of a periodic motion of the subject

A computed tomography (CT) apparatus comprising:

• a CT scanner having an x-ray source with a focus and a matrix-like detector array for scanning a subject, having a region exhibiting a periodic motion, with a conical x-ray beam emanating from said focus and detecting said beam, after attenuation by said subject, with said matrix-like detector array while moving said focus along a spiral path around said subject relative to a system axis, said detector array generating output data dependent on radiation from said x-ray beam that is incident thereon;
• a signal acquisition unit adapted for interaction with said subject for obtaining a signal from said subject representing said periodic motion;
• a computer supplied with said output data and said signal, said computer dividing said output data, for a segment of said spiral path having a length adequate for reconstructing a CT image, into a plurality of datasets respectively for a plurality of sub-segments of said segment, each of said sub-segments having a length shorter than said length adequate for reconstructing a CT image;
• said computer, for each of said sub-segments, reconstructing a plurality of segment images having a plane inclined relative to said system axis from the dataset for that sub-segment;
• said computer allocating a z-position on said system axis and a time position with respect to said periodic motion to the respective segment images;
• said computer selecting segment images within a range of z-positions and a range of time positions so that respective sub-segments for the selected segment images comprise a total length adequate for reconstruction of a CT image;
• and
• said computer combining said selected segment images at least indirectly to form a resulting CT image with respect to a target image plane.