US 5,671,263 A · Motion artifact suppression filter for use in computed tomography systems

Abstract

The disclosed motion artifact filter generates motion corrected signals from projection data signals to compensate for motion artifacts in CT images. Each measurement of the projection data signals is representative of the density of all the mass occupying a volume between an X-ray source and a detector at a particular projection angle. The motion artifact filter includes a high pass filter for generating high frequency signals representative of patient movement. Each measurement of the high frequency signals is generated by combining groups of measurements of the projection data signals corresponding to volumes that are proximal to each other. Each measurement of the motion corrected signals is generated by subtracting a portion of a measurement of a high frequency signal from its associated measurement of a projection data signal. The portions increase as the projection angle approaches a starting angle and the portions decrease as the projection angle approaches an intermediate angle.

Claims34

Dependent claims

In a computed tomography system for generating an image of a portion of an object positioned within an imaging field, the system including scanning means for generating data from a plurality of projections at a corresponding plurality of projection angles of a scan, including projection angles that are 180N degrees apart, wherein N is one or more whole integers, so as to provide at least pairs of opposing projections, an artifact suppression filter comprising:

comparison means for comparing, for each of said pairs of opposing projections, the data from opposing projections so as to determine if artifact errors exist between the two projections of each pair and providing an indication if the comparison indicates a difference between said data above a predetermined amount;
and
means for adjusting the data for at least one of the opposing projections if the comparison means indicates the difference between the data is above the predetermined amount so as to compensate for such artifact errors.

In a computed tomography system for generating an image of an object, the system including scanning means for generating a plurality of projections at a corresponding plurality of projection angles, each of the projections including a plurality of projection data signal measurements respectively representative of the density of mass occupying a corresponding volume of space during the measuring time associated with the projection, an artifact suppression filter comprising:

(A) high pass filter means, responsive to said plurality of projection data signal measurements, for generating a plurality of high frequency signal measurements, each of said high frequency signal measurements being a function of a group of the projection data signal measurements, each group of the projection data signal measurements including a first measurement and a second measurement, the volume associated with the first measurement being proximal to the volume associated with the second measurement, the first measurement being generated at a first projection angle and the second measurement being generated at a second projection angle;
and
(B) correction means for generating a plurality of correction signal measurements, each correction signal measurement having an associated one of the projection data signal measurements and an associated one of the high frequency signal measurements, each correction signal measurement being generated by shifting its associated one projection data signal measurement by a portion of its associated high frequency signal measurement the portion increasing as the projection angle corresponding to the one associated projection data signal measurement approaches a starting angle and the portion decreasing as the corresponding projection angle approaches an intermediate angle.

Dependencies are inferred from the claim text.

Motion artifact suppression filter for use in computed tomography systems

Life of this patent

Motion artifact suppression filter for use in computed tomography systems

Life of this patent

Abstract

Claims34