System and method to determine the location and orientation of an indwelling medical device
First Claim
1. A system for detecting a position of a plurality of magnets within a patient from a measurement location outside the patient, the system comprising:
- a housing;
a plurality of magnetic sensors supported by the housing, each of the plurality of sensors being oriented in a known direction and generating a set of signals as a function of static magnetic field strength and direction due to the plurality of magnets within the patient;
a processor configured to calculate an estimated position of each of the plurality of magnets in a three-dimensional space and to calculate values of a predicted magnetic field strength for at least a portion of the plurality of sensors based on the estimated positions of each of the plurality of magnets, the processor further configured to calculate values of an actual magnetic field strength using the set of signals and determining values of the location of each of the plurality of magnets based on the difference between the values of the predicted magnetic field strength and the values of the actual magnetic field strength; and
a display providing a visual display of the position of each of the plurality of magnets in the three-dimensional space.
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Accused Products
Abstract
A device to detect the location of a plurality of magnets uses a plurality of magnetic sensors, having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by each of the plurality of magnets and provides data indicative of the direction of the magnets in a three-dimensional space. The device uses fundamental equations for electricity and magnetism that relate the measured magnetic field strength to the location and strength of the magnetic dipole for each of the plurality of magnets. The device may use an iterative process to determine the actual location and orientation of each magnet. An initial estimation of the location and orientation of each magnet results in the generation of predicted magnetic field values. The predicted magnetic field values are compared with the actual measured values provided by the magnetic sensors. Based on a difference between the predicted values and the measured values, the device estimates a new location for each of the magnets and calculates new predicted magnetic field strength values. The iteration process continues until the predicted values match the measured values within a desired degree of tolerance. At this point, the estimated location and orientation of each of the magnets matches the actual location within a predetermined degree of tolerance.
416 Citations
28 Claims
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1. A system for detecting a position of a plurality of magnets within a patient from a measurement location outside the patient, the system comprising:
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a housing;
a plurality of magnetic sensors supported by the housing, each of the plurality of sensors being oriented in a known direction and generating a set of signals as a function of static magnetic field strength and direction due to the plurality of magnets within the patient;
a processor configured to calculate an estimated position of each of the plurality of magnets in a three-dimensional space and to calculate values of a predicted magnetic field strength for at least a portion of the plurality of sensors based on the estimated positions of each of the plurality of magnets, the processor further configured to calculate values of an actual magnetic field strength using the set of signals and determining values of the location of each of the plurality of magnets based on the difference between the values of the predicted magnetic field strength and the values of the actual magnetic field strength; and
a display providing a visual display of the position of each of the plurality of magnets in the three-dimensional space. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for detecting a position of a plurality of magnets within a patient from a measurement location on the surface of the patient, the method comprising:
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positioning a plurality of magnetic sensors at predetermined locations wherein the location and orientation of each of the plurality of magnetic sensors is known;
detecting a static magnetic field strength and direction due to the plurality of magnets within the patient using the plurality of magnetic sensors;
generating a set of signals as a function of the detected static magnetic field strength and direction due to the plurality of magnets;
calculating an estimated position of each of the plurality of magnets in a three-dimensional space;
calculating expected values of magnetic field strength for at least a portion of the plurality of sensors based on the estimated positions of the plurality of magnets;
calculating actual values of an actual magnetic field strength using the set of signals;
determining values of the location of each of the plurality of magnets based on the difference between the expected values and the actual values; and
displaying values of the position of each of the plurality of magnets in the three-dimensional space. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification