Method and arrangement for compensating motion artifacts in computed tomography

Claim 1

A computed tomography device for determining the spatial distribution of the absorption of radiation in a planar slice of a body from a plurality of measuring sets, each of which represent a series of measuring values which correspond to an integral of the absorption of the body along one of a multiplicity of at least substantially parallel measuring beams, in which the various measuring sets are derived from measuring values obtained with the aid of measuring beams which are differently oriented relative to each other within the planar slice and the spatial distribution of the absorption is derived from the sets of measuring values by superposition, of the type comprising a radiator for generating a beam of a body penetrating radiation and one or a plurality of detectors for measuring the radiation passing through the planar slice of the body, the measurements being performed with radiation passing at different orientations through the planar slice of the body, the direction of the radiation being in the plane of said slice; a memory of storing the series of measuring values; and a first arithmetic unit for determining the spatial absorption distribution in the planar slice by superposition; and further comprising, as an improvement: second arithmetic unit means connected to the memory, which functions to calculate the coordinates of a weighted-mean point (S,β) for each series of measuring values (Q(p,β)) measured with at least substantially the same orientation in accordance with the relationship ##EQU5## a weighted-mean memory for storing the weighted-mean points; third arithmetic unit means which function to calculate the value of the perpendicular weighted-mean distance (D(Gβ,B)) from the line through the weighted-mean point to the coordinates (B x , B y ) of a fixed point (B), for each weighted-mean point, using in accordance with the relationship ΔSβ = Sβ + B.sub.x sinβ - B.sub.y cosβ; and a distance memory for storing the weighted-mean distances; the first arithmetic unit being connected to determine the distribution of absorption in the planar slice using the measuring values of measuring series shifted by the associated weighted-mean distance.