Magnetic field distortion detection and correction in a magnetic localization system
AssigneeSt. Jude Medical International Holding S.à r.l.
InventorsEric S. Olson, Alon Izmirli, Guy Hevel
Life of this patent
Estimating the term…
Abstract
Various embodiments of the present disclosure identify and correct for magnetic field distortions within a magnetic field for localization of a medical device within a patient. Such magnetic field distortions, often associated with the intrusion of a metallic object into the magnetic field, may cause an unacceptable level of localization error which aspects of the present disclosure correct for.
Claims14
A system to detect and correct for magnetic distortion in a magnetic field for localizing a medical device positioned within the magnetic field, the system comprising:
- a magnetic field emitter including one or more emitter coils at known positions and orientations within the system, each of the one or more emitter coils configured and arranged to emit the magnetic field;
- one or more sensor coils, each of the one or more sensor coils configured and arranged to sense the magnetic field, and output a first electrical signal indicative of the sensed magnetic field at the medical device;
- an array of magnetic distortion sensors at known positions and orientations within the system, each of the magnetic distortion sensors in the array configured and arranged to sense the magnetic field, and output a second electrical signal indicative of the sensed magnetic field at the respective magnetic distortion sensor;
- and
- processor circuitry communicatively coupled to each of the magnetic distortion sensors and the one or more sensor coils, and configured and arranged to
- receive the first and second electrical signals, and
- determine a magnetic distortion corrected position of the medical device within the system based on the first and second electrical signals by
- determining perceived locations of each of the magnetic distortion sensors in the array based on the sensed magnetic field at each of the magnetic distortion sensors,
- determining a localized error between the perceived location and the known position of each of the magnetic distortion sensors,
- calculating a transform, based on the localized error determinations, that converts the perceived locations to the known position for each of the magnetic distortion sensors, and using the calculated transform, and
- group the perceived locations of the magnetic distortion sensors and determine a gradient of deformation for the group,
- based on the localized error and the determined gradient of deformation for the group, calculate an enhanced transform with spline smoothing, and
- using the enhanced transform to compensate for non-linear deformation at mid-points between the known positions of the group based at least in part on the determined gradient of deformation for the group.
A computer program for correcting magnetic distortion in a magnetic field for localization of a medical device within a patient, the computer program embodied on a non-transitory computer readable medium and comprising:
- calculating a perceived location of each of a plurality of sensor coils in a sensor array based upon a received signal at each of the plurality of sensor coils indicative of the magnetic field proximate the respective sensor coil;
- determining a positional error of each of the plurality of sensor coils indicative of a magnetic distortion in the magnetic field at each of the respective sensor coils, based on a discrepancy between a known position of each of the respective sensor coils and the perceived location of each of the respective sensor coils;
- computing a transform, based on the discrepancy between the known position and perceived locations of each of the plurality of sensor coils, that converts the perceived location to the known position for each of the plurality of sensor coils;
- calculating a perceived location of the medical device based upon a received signal at the medical device indicative of the magnetic field proximate the medical device;
- and
- determining an actual location of the medical device by entering the perceived location of the medical device into the computed transform;
- wherein the transform is calculated using a thin plate spline where the solution is a sum of a set of weighted basis functions centered at each control point, where the weighted basis function is:
- r2 log r, for the case of f:
- R2⇒R1
- and
- r, for the case of f:
- R3⇒R3,
- where r is a radial distance of an input point from the particular weighted basis function's center.
Dependencies are inferred from the claim text.