# US 8,571,293 B2 · Motion tracking system for real time adaptive imaging and spectroscopy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,571,293 B2 - Document ID: US8571293B2 - Status: Granted - Kind: B2 - Application number: 13/735,907 - Filed: 2013-01-07 - Published: 2013-07-25 - Granted: 2013-10-29 - Earliest claimed: 2006-05-19 - Assignees: The Queen's Medical Center; University of Hawaii; The Medical College of Wisconsin, Inc.; UWM Research Foundation, Inc. - Applicants: The Queen's Medical Center; The University of Hawaii; The Medical College of Wisconsin, Inc.; UWM Research Foundation, Inc. - Inventors: Thomas Michael Ernst; Thomas Edmund Prieto; Brian Stewart Randall Armstrong - Web page: https://patentgrep.com/patent/US8571293B2 ## CPC - A61B 5/055: involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging - A61B 5/0077: {Devices for viewing the surface of the body, e.g. camera, magnifying lens} - A61B 5/1127: {using markers} - A61B 5/1128: {using image analysis (A61B5/1127 takes precedence)} - A61B 5/721: {using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured} - A61B 5/7292: {Prospective gating, i.e. predicting the occurrence of a physiological event for use as a synchronisation signal} - A61B 6/0492: {using markers or indicia for aiding patient positioning} - A61B 6/547: {involving tracking of position of the device or parts of the device} - G01R 33/28: Details of apparatus provided for in groups G01R33/44 - G01R33/64 - G01R 33/56509: {due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence)} - G06T 7/0012: {Biomedical image inspection} - G06T 7/70: Determining position or orientation of objects or cameras (camera calibration G06T7/80) - H04N 7/18: Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast - G06V 10/62: relating to a temporal dimension, e.g. time-based feature extraction; Pattern tracking - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract This invention relates to a system that adaptively compensates for subject motion in real-time in an imaging system. An object orientation marker (30), preferably a retro-grate reflector (RGR), is placed on the head or other body organ of interest of a patient (P) during a scan, such as an MRI scan. The marker (30) makes it possible to measure the six degrees of freedom (x, y, and z-translations, and pitch, yaw, and roll), or “pose”, required to track motion of the organ of interest. A detector, preferably a camera (40), observes the marker (30) and continuously extracts its pose. The pose from the camera (40) is sent to the scanner (120) via an RGR processing computer (50) and a scanner control and processing computer (100), allowing for continuous correction of scan planes and position (in real-time) for motion of the patient (P). This invention also provides for internal calibration and for co-registration over time of the scanner's and tracking system's reference frames to compensate for drift and other inaccuracies that may arise over time. ## Claims ### Claim 1 A motion tracking system for an object in a magnetic resonance imaging scanner, the system comprising: an object orientation marker configured to be coupled to the object; at least two detectors configured to periodically image the object orientation marker, the at least two detectors each configured to view the object orientation marker along a different line of sight; and a tracking system configured to analyze images generated by the at least two detectors to determine changes in position of the object orientation marker, and to generate tracking data for use by the magnetic resonance imaging scanner to dynamically adjust scans to compensate for the changes in position of the object orientation marker; wherein the tracking system comprises a computer processor and an electronic memory. ### Claim 2 (depends on 1) The motion tracking system of claim 1, wherein the tracking system is further configured to predict changes in position of the object orientation marker by analyzing a plurality of previously determined changes in position of the object orientation marker. ### Claim 3 (depends on 1) The motion tracking system of claim 1, wherein each of the at least two detectors comprises a camera. ### Claim 4 (depends on 1) The motion tracking system of claim 1, wherein the object orientation marker indicates orientation in at least three degrees of freedom. ### Claim 5 (depends on 1) The motion tracking system of claim 1, wherein the object orientation marker indicates orientation in six degrees of freedom. ### Claim 6 (depends on 1) The motion tracking system of claim 1, wherein the object orientation marker is an RGR. ### Claim 7 (depends on 1) The motion tracking system of claim 1, wherein at least one of the at least two detectors is configured to be positioned within the magnetic resonance imaging scanner. ### Claim 8 (depends on 1) The motion tracking system of claim 1, wherein each of the at least two detectors is configured to be positioned within the magnetic resonance imaging scanner. ### Claim 9 (depends on 1) The motion tracking system of claim 1, further comprising at least one mirror configured to provide an indirect line of sight between the object orientation marker and at least one of the at least two detectors. ### Claim 10 (depends on 1) The motion tracking system of claim 1, wherein the at least two detectors are configured to be positioned to enable at least one detector to view the object orientation marker when the sight line from another detector to the object orientation marker is obstructed. ### Claim 11 A motion tracking system for an object in a scanner, the system comprising: an object orientation marker configured to be coupled to the object; a scanner configured to scan the object; at least two detectors configured to periodically image the object orientation marker, the at least two detectors each configured to view the object orientation marker along a different line of sight; and a tracking system configured to analyze images generated by the at least two detectors to determine changes in position of the object orientation marker, and to generate tracking data for use by the scanner to dynamically adjust scans to compensate for the changes in position of the object orientation marker; wherein the tracking system comprises a computer processor and an electronic memory. ### Claim 12 (depends on 11) The motion tracking system of claim 11, wherein the scanner is one of a MR scanner, a PET scanner, a SPECT scanner, a CT scanner, and a digital angiographic scanner. ### Claim 13 (depends on 11) The motion tracking system of claim 11, wherein the tracking system is further configured to predict changes in position of the object orientation marker by analyzing a plurality of previously determined changes in position of the object orientation marker. ### Claim 14 (depends on 11) The motion tracking system of claim 11, wherein each of the at least two detectors comprises a camera. ### Claim 15 (depends on 11) The motion tracking system of claim 11, wherein the object orientation marker indicates orientation in at least three degrees of freedom. ### Claim 16 (depends on 11) The motion tracking system of claim 11, wherein the object orientation marker indicates orientation in six degrees of freedom. ### Claim 17 (depends on 11) The motion tracking system of claim 11, wherein the object orientation marker is an RGR. ### Claim 18 (depends on 11) The motion tracking system of claim 11, wherein at least one of the at least two detectors is configured to be positioned within the scanner. ### Claim 19 (depends on 11) The motion tracking system of claim 11, wherein each of the at least two detectors is configured to be positioned within scanner. ### Claim 20 (depends on 11) The motion tracking system of claim 11, wherein the at least two detectors are configured to be positioned to enable at least one detector to view the object orientation marker when the sight line from another detector to the object orientation marker is obstructed.