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:] [6.] 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 housing;first, second, and third magnetic sensors mounted in the housing, the first sensor positione

[ What is claimed is:] [6.] 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 housing;first, second, and third magnetic sensors mounted in the housing, the first sensor positioned at a first distance from a magnet and generating a first set of electrical signals as a function of a first magnetic field strength and direction due to the magnet, the second sensor positioned at a second distance from the magnet and generating a second set of electrical signals as a function of a second magnetic field strength and direction due to the magnet, and the third sensor positioned at a third distance from the magnet and generating a third set of electrical signals as a function of a third 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 the first, second and third sensors based on the estimated position and to calculate a measured magnetic field strength using the first, second, and third sets of electrical signals, the processor generating an error function based on a difference between the predicted magnetic field strength and the measured magnetic field strength; anda two-dimensional display providing a visual display of the three-dimensional position of the magnet using the error function wherein at least a portion of the display is transparent to allow the user to view the surface of the patient beneath the transparent portion.