초록 ▼

A device to detect the location of a magnet coupled to an indwelling medical device within a patient uses three or more sets of magnetic sensors each having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by the magnet and provides data i

A device to detect the location of a magnet coupled to an indwelling medical device within a patient uses three or more sets of magnetic sensors each having sensor elements arranged in a known fashion. Each sensor element senses the magnetic field strength generated by the magnet and provides data indicative of the direction of the magnet in a three-dimensional space. The device uses findamental equations for electricity and magnetism that relate measured magnetic field strength and magnetic field gradient to the location and strength of a magnetic dipole. The device uses an iterative process to determine the actual location and orientation of the magnet. An initial estimate of the location and orientation of the 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 the difference between the predicted values and the measured values, the device estimates a new location of the magnet and calculates new predicted magnetic field strength values. This iteration process continues until the predicted values match the measured values within a desired degree of tolerance. At that point, the estimated location matches the actual location within a predetermined degree of tolerance. A two-dimensional display provides an indication of the location of the magnet with respect to the housing of the detector. A depth indicator portion of the display can be used to provide a relative or absolute indication of the depth of the magnet within the patient.

대표청구항 ▼

[ What is claimed is:] [8.]8. A method for detecting a position of a magnet associated with an indwelling medical device from a measurement location on the surface of a patient in the presence of a magnetic field of the Earth, the method comprising the steps of:positioning a plurality of magnetic se

[ What is claimed is:] [8.]8. A method for detecting a position of a magnet associated with an indwelling medical device from a measurement location on the surface of a patient in the presence of a magnetic field of the Earth, the method comprising the steps of:positioning a plurality of magnetic sensors at the measurement location, the plurality of magnetic sensors having a known spactial relationship with respect to each other;generating a set of electrical signals related to magnetic field strength and direction due to the magnet;calculating an estimated position of the magnet;calculating a predicted value related to the magnetic field strength for the plurality of sensors based on the estimated position;measuring measured values related to the magnetic field strength for the plurality of sensors based on the sets of electrical signals;processing the measured values to cancel the effects of the Earth's magnetic field;comparing the predicted value related to the magnetic field strength with the measured value related to the magnetic field strength to determine the three-dimensional position of the magnet; anddisplaying data to indicate the three-dimensional position of the magnet.