Patent ID: 6556697
Filing Date: 2003-04-29
Classification: A61B

Abstract:
An image reconstruction method for obtaining an image of a periodically moving object, experiencing successive periods each having a motion phase and a resting phase, using a detector unit having a first detector line and a last detector line disposed on a carrier opposite an x-ray source, said carrier being rotatable around a rotational axis and said detector lines being oriented substantially at a right angle relative to said rotational axis, said method comprising the steps of:rotating said carrier at a rotational speed around said rotational axis so that said x-ray source proceeds through rotational angles; for each rotational angle in a plurality of rotational angles, simultaneously registering respective measured datasets from the respective detector lines during a plurality of said periods; selecting a phase reference point in each of said periods and identifying a phase range in each of said periods relative to said phase reference point, and registering said measured datasets at least during the respective phase ranges of said periods; identifying a duration of said phase ranges and identifying a phase angle range which is swept during each phase range, and selecting said plurality of periods so that a product of said plurality of periods and said phase angle range corresponds to a reconstruction angle range required for reconstruction of an image of said object; and reconstructing said image of said object from said measured datasets using a three-dimensional back-projection algorithm, comprising for each phase range, combining the measured datasets registered during that phase range to form a rotational angle group; for each rotational angle group, determining a reference angle corresponding to the phase reference point for that phase range during which the said measured datasets are combined; for each rotational angle, identifying each rotational angle group having a reference angle which is at least as large as that rotational angle, to obtain a set of rotational angle groups; and identifying measured datasets, as identified measured datasets, of a rotational angle group within said set of rotational angle groups for which a difference between the rotational angle and the reference angle is minimum, and utilizing only said identified measured datasets for reconstructing said image.