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 fundamental 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:] [27.] A system for detecting a position of a magnet associated with an indwelling medical device from a measurement location on the surface of a patient, the system comprising:a plurality of magnetic sensors maintained in fixed position with respect to each other, each of the

[ What is claimed is:] [27.] A system for detecting a position of a magnet associated with an indwelling medical device from a measurement location on the surface of a patient, the system comprising:a plurality of magnetic sensors maintained in fixed position with respect to each other, each of the magnetic sensors being oriented in a known direction and generating signals as a function of static magnetic field strength and direction due to the magnet;a processor to calculate an estimated position of the magnet in a three-dimensional space and to calculate a predicted magnetic field strength for at least a portion of the plurality of sensors based on the estimated position, the processor further calculating an actual magnetic field strength for the portion of sensors using signals and generating an error function based on a difference between the predicted magnetic field strength and the actual magnetic field strength; anda display providing a visual display of data related to the position of the magnet in the three-dimensional space based on the error function.