Method for reducing motion induced image artifacts in projection imaging

• US 4,994,965 A
• Filed: 11/23/1988
• Issued: 02/19/1991
• Est. Priority Date: 11/23/1988
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Pelc, Norbert J., Crawford, Carl R.
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): Kibby, Steven
• Application Number:
  US07/276,249
• Time in Patent Office: 818 Days
• Field of Search: 364/413.15, 324/309, 128/653 R, 378/4, 378/95, 378/901
• US Class Current: 378/95
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2211/412 Dynamic

Abstract

A method of reducing image artifacts in tomographic, projection imaging systems due to periodic motion of the object being imaged includes the acquisition of a signal indicative of the periodic motion. This signal is used to identify a quiescent period in the periodic motion so that the acquisition of projection data may be coordinated to be centered within the quiescent period. The sequence of the angles at which projection data is acquired is controlled so that the primary axis of periodic motion is perpendicular to the axis of projection at the center of the quiescent period. Multiple periodic signals may be coordinated by awaiting their best alignment over a fixed number of cycles of one of the periodic motions.

Claims

1. A method for reducing image artifacts in an image object resulting from periodic motion of the object, where the image is produced from a projection set taken continuously during an acquisition period along a plurality of projection axes about the object, the periodic motion having a quiescent period during which the periodic motion is at a minimum, the quiescent period being less than the acquisition period, said method comprising:

producing a signal indicative of said periodic motion;

producing a series of reference signals which indicate a pre-established point in each of a series of said periodic motions;

relating the quiescent period to the pre-established point in each reference signal;

starting the acquisition period at a time related to the reference signal so that the acquisition period for the projection set is centered around the quiescent period.

2. The method described in claim 1 wherein the periodic motion is respiratory motion.

3. The method described in claim 1 wherein the periodic motion is cardiac motion.

4. A method for reducing image artifacts resulting from periodic motion of an object, where the image is produced from a set of projections taken along a plurality of projection axes about the object, said method comprising:

identifying a principal axis of the periodic motion;

controlling the sequence of projection axes so that the range of projection axes is centered on an angle perpendicular to the principal axis of the periodic motion.

5. A method for reducing image artifacts resulting from a primary periodic motion and at least one secondary periodic motion of an object, where the image is produced from a set of projections taken along a plurality of projection axes about the object, said method comprising:

producing a signal indicative of each said periodic motion;

producing a series of reference signals for each said periodic motion which indicate pre-established points in each cycle of said periodic motions;

identifying centerpoints in quiescent periods related to the pre-established points in each reference signal;

examining a predetermined time interval of the primary periodic motion to identify a quiescent period, related to the reference signal for the primary periodic motion, in which the centerpoints among the primary and secondary periodic motions are closest;

starting the acquisition of projections at a time related to the primary periodic motion'"'"'s reference signal so that the total acquisition time for one projection set is centered in the identified quiescent period.

6. The method described in claim 5 including the additional steps of:

identifying a principal axis of the periodic motion;

controlling the sequence of projection axes so that the range of projection axes are centered on an angle perpendicular to the principal axis of the periodic motion.

7. An apparatus for producing tomographic images of objects with periodic motion, where each image is reconstructed from a set of projections acquired from detectors on a rotating gantry, the apparatus comprising:

a transducer producing a signal indicative of said periodic motion;

a detector producing a series of reference signals which indicate a preestablished point in each of a series of said periodic motions;

a computer means for identifying a quiescent period related to the pre-established point in each reference signal;

a gantry controller means for starting the acquisition of projections at a time related to the reference signal so that the total acquisition time for one projection set is centered in the quiescent period.

8. A method for reducing image artifacts in an image of an object resulting from periodic motion of the object, where the image is produced from a projection set of projections acquired during an acquisition period along a plurality of projection axes about the object, the periodic motion having a quiescent period during which the periodic motion is at a minimum and the quiescent period being less than the acquisition period, said method comprising:

producing a signal indicative of said periodic motion;

producing a series of reference signals which indicate a pre-established point in each of a series of said periodic motions;

relating the quiescent period to the pre-established point in each reference signal;

starting the acquisition of projections at a time related to the reference signal and preceding the quiescent period by no less than than half of the length of the acquisition period;

ending the acquisition of projections at a time related to the reference signal and succeeding the quiescent period by no less than half the length of the acquiescent period; and

selecting a continuous subset of projections from the acquired projections to form the projection set so that the acquisition period is centered around the quiescent period.