Method and system for marker localization

A computer-based method for locating a marker comprising a resonating magnetic circuit configured to exhibit a dipole magnetic moment and to generate a magnetic field in response to a wirelessly transmitted excitation signal, the marker being implanted in or affixed to an organism, the marker being located within a bounding box having grid points, the marker being located at a marker point within the bounding box, the method comprising:

• receiving a set of actual measurements, each actual measurement indicative of a component of the magnetic field at each of a plurality of sensors, the sensors being substantially planar;
• providing sets of reference measurements, each reference measurement being associated with one Cartesian component of the magnetic moment, each set of reference measurements being associated with a grid point such that when the marker is at that grid point the actual measurement is expected to be a linear combination of that set;
• identifying a grid point that is close to the marker point by evaluating for various grid points an objective function that indicates the closeness of the set of actual measurements to the set of reference measurements at that grid point;
• and
• identifying as the marker point a point associated with a set of calculated measurements that closely matches the set of actual measurements wherein the set of calculated measurements is derived from the sets of reference measurements and based on the objective function.

A system for locating a dipole source of a magnetic field, the dipole source being a marker implanted in or affixed to an object, the method comprising:

• means for receiving a set of actual measurements, each actual measurement indicative of a component of the magnetic field at each of a plurality of sensors;
• means for selecting the location associated with a set of reference measurements that most closely matches the received set of actual measurements, each set of reference measurements being associated with a location such that an actual measurement from that location is expected to be a linear combination of that set;
• and
• means for identifying a location associated with a set of interpolated reference measurements that most closely matches the set of actual measurements.

A computer-based method for locating a dipole source of a magnetic field, subject to interference from other sources, the dipole source being a marker implanted in or affixed to an organism, the method comprising:

• receiving a set of actual measurements, each actual measurement indicative of a component of the magnetic field and a component of the interference at each of a plurality of sensors;
• providing sets of reference measurements, each set of reference measurements being associated with a location such that an actual measurement from that location in the absence of interference is expected to be a linear combination of that set;
• providing a set of augmented measurements, such that interference at the sensors is expected to be a linear combination of that set;
• and
• selecting the location associated with the set of reference measurements as augmented by the set of augmented measurements that most closely matches the received set of actual measurements.

A computer-based method for locating a dipole source of a magnetic field, subject to interference from other sources, the dipole source being a marker implanted in or affixed to an organism, the method comprising:

• receiving a set of actual measurements, each actual measurement indicative of a component of the magnetic field wherein the reliability of the actual measurements varies;
• providing sets of reference measurements, each set of reference measurements being associated with a location such that an actual measurement from that location is expected to be a linear combination of that set;
• providing a set of reliability weights that reflects the reliability of the actual measurements;
• and
• selecting the location associated with the set of reference measurements that most closely matches the received set of actual measurements factoring in the reliability weights.