Abstract: A system comprising: a magnetic transmitter configured to generate magnetic fields; a magnetic sensor configured to generate signals based on characteristics of the magnetic fields; and one or more computer systems configured to: cause the magnetic transmitter to generate a first plurality of magnetic fields at a first frequency; receive a first plurality of signals from the magnetic sensor; determine data indicative of a position and orientation of the magnetic sensor at a first position of the magnetic sensor; determine a distortion term that corresponds to a first position of the magnetic sensor; cause the magnetic transmitter to generate a third plurality of magnetic fields at the first frequency; receive a third plurality of signals from the magnetic sensor; and determine a second position and orientation of the magnetic sensor relative to the magnetic transmitter, wherein the first frequency is greater than the second frequency.

Abstract: A calibration system comprising: a Helmholtz device comprising thee pairs of coils defining an inner volume, wherein each of the three pairs of coils is configured to generate a magnetic field that is uniform throughout the inner volume; a mount configured to accept a device that includes a magnetic sensor, wherein at least a portion of the mount is positioned within the inner volume such that the magnetic sensor is positioned at or near a center of the inner volume when the device is positioned on the mount; and a computer system configured to communicate with the Helmholtz device and the magnetic sensor, wherein the computer system is configured to: provide instructions to cause each of the three pairs of coils to generate a magnetic field; receive signals from the magnetic sensor that are based on characteristics of the magnetic fields received at the magnetic sensor; measure, based on the signals received from the magnetic sensor, one or more characteristics of the magnetic sensor; and determine, using a

Abstract: A calibration device comprising: a plurality of magnetic sensors positioned at the calibration device, the plurality of magnetic sensors defining a space; a controller configured to be positioned in the space defined by the plurality of magnetic sensors, wherein the controller includes a magnetic transmitter; and one or more processors configured to: cause the magnetic transmitter to generate magnetic fields; receive signals from the plurality of magnetic sensors that are based on characteristics of the magnetic fields received at the plurality of magnetic sensors; calculate, based on the signals received from the plurality of magnetic sensors, positions and orientations of the plurality of magnetic sensors relative to a position and orientation of the magnetic transmitter; and determine whether the calculated positions and orientations of the plurality of magnetic sensors are within one or more threshold limits of known positions and orientations of the plurality of magnetic sensors.

Abstract: A system comprising: a transmitter that includes at least three coils, the transmitter configured to generate magnetic fields; a sensor that includes at least three coils, the sensor configured to provide sensor signals that correspond to the magnetic fields generated by the transmitter; and a computing device in communication with the transmitter and the sensor, the computing device configured to compare a first sensor signal and a second sensor signal, and based on the comparison, determine whether any of the sensor coils are locked to a corresponding frequency out-of-phase.

Abstract: An improved system for magnetic position tracking of a device includes a magnetic transmitter, a magnetic sensor, a computing system and a polarity inverter. The magnetic transmitter includes at least one transmitter coil that outputs a transmitted magnetic field having a time derivative component. The magnetic sensor includes at least one sensor coil that has coil terminals having a polarity, and the sensor coil is responsive to the time derivative component of the transmitted magnetic field and outputs a sensor signal. The computing system computes position and angular orientation data of a device based on the sensor signal and the polarity inverter is configured to connect to the coil terminals and to cause the polarity of the coil terminals to be reversed according to a switching signal.

Abstract: An improved system for magnetic position tracking of a device includes a magnetic transmitter, a magnetic sensor, a computing system and a polarity inverter. The magnetic transmitter includes at least one transmitter coil that outputs a transmitted magnetic field having a time derivative component. The magnetic sensor includes at least one sensor coil that has coil terminals having a polarity, and the sensor coil is responsive to the time derivative component of the transmitted magnetic field and outputs a sensor signal. The computing system computes position and angular orientation data of a device based on the sensor signal and the polarity inverter is configured to connect to the coil terminals and to cause the polarity of the coil terminals to be reversed according to a switching signal.

Abstract: Among other things, the disclosure features a system comprising a sensor, a DC magnetic field source, an AC magnetic field source, and a receiver. The sensor has an aspect ratio of 10:1 or higher and comprises a ferromagnetic material. The ferromagnetic material has a non-linear magnetization response, and the response contains a maximum point of non-linearity. The DC magnetic field source is adjustable for providing a magnetic excitation field to excite a magnetic field within the sensor. The provided magnetic excitation field has a range such that the excited magnetic field within the sensor is near the maximum point of non-linearity. The AC magnetic field source is configured to generate an AC magnetic field to cause the sensor to generate even harmonics. The receiver is configured to receive the even harmonics from the sensor for determining a position of the sensor.

Abstract: Among other things, the disclosure features a system comprising a sensor, a DC magnetic field source, an AC magnetic field source, and a receiver. The sensor has an aspect ratio of 10:1 or higher and comprises a ferromagnetic material. The ferromagnetic material has a non-linear magnetization response, and the response contains a maximum point of non-linearity. The DC magnetic field source is adjustable for providing a magnetic excitation field to excite a magnetic field within the sensor. The provided magnetic excitation field has a range such that the excited magnetic field within the sensor is near the maximum point of non-linearity. The AC magnetic field source is configured to generate an AC magnetic field to cause the sensor to generate even harmonics. The receiver is configured to receive the even harmonics from the sensor for determining a position of the sensor.

Abstract: A magnetic field sensor assembly includes a hollow cylindrical core, conductive material and at least first and second lead wires. The hollow cylindrical core is made of ferromagnetic material and has a proximal end and a distal end. The conductive material is disposed around the hollow cylindrical core and forms at least one turn of a coil that has at least one start terminal and at least one finish terminal. The first and second lead wires pass through the center of the hollow cylindrical core and the first lead wire is connected to the start terminal thereby forming a first termination and the second lead wire is connected to the finish terminal thereby forming a second termination. The first and second terminations are positioned within the hollow cylindrical core.

Abstract: Miniaturized, five and six degrees-of-freedom magnetic sensors, responsive to pulsed DC magnetic fields waveforms generated by multiple transmitter options, provide an improved and cost-effective means of guiding medical instruments to targets inside the human body. The end result is achieved by integrating DC tracking, 3D reconstructions of pre-acquired patient scans and imaging software into a system enabling a physician to internally guide an instrument with real-time 3D vision for diagnostic and interventional purposes. The integration allows physicians to navigate within the human body by following 3D sensor tip locations superimposed on anatomical images reconstructed into 3D volumetric computer models. Sensor data can also be integrated with real-time imaging modalities, such as endoscopes, for intrabody navigation of instruments with instantaneous feedback through critical anatomy to locate and remove tissue.

Abstract: A magnetic field sensor assembly includes a hollow cylindrical core, conductive material and at least first and second lead wires. The hollow cylindrical core is made of ferromagnetic material and has a proximal end and a distal end. The conductive material is disposed around the hollow cylindrical core and forms at least one turn of a coil that has at least one start terminal and at least one finish terminal. The first and second lead wires pass through the center of the hollow cylindrical core and the first lead wire is connected to the start terminal thereby forming a first termination and the second lead wire is connected to the finish terminal thereby forming a second termination. The first and second terminations are positioned within the hollow cylindrical core.

Abstract: An improved system for magnetic position tracking of a device includes a magnetic transmitter, a magnetic sensor, a computing system and a polarity inverter. The magnetic transmitter includes at least one transmitter coil that outputs a transmitted magnetic field having a time derivative component. The magnetic sensor includes at least one sensor coil that has coil terminals having a polarity, and the sensor coil is responsive to the time derivative component of the transmitted magnetic field and outputs a sensor signal. The computing system computes position and angular orientation data of a device based on the sensor signal and the polarity inverter is configured to connect to the coil terminals and to cause the polarity of the coil terminals to be reversed according to a switching signal.

Abstract: An electromagnetic needle tracking system includes a needle assembly, a calibration system and a computing system. The needle assembly includes a needle stylet and a sensor assembly. The sensor assembly includes a sensor that measures position and angular orientation data when placed within an electromagnetic field. The calibration system measures the sensor's position and angular orientation for a known needle tip position and angular orientation within a calibration fixture and calculates a position offset and an angular orientation offset of the sensor relative to the needle tip position and angular orientation. The computing system computes position and angular orientation data of the needle tip by adding the sensor position offset and angular orientation offset to the measured position and angular orientation data, respectively.

Abstract: In one aspect, in general, a method includes receiving, at a computer system, data from an electromagnetic sensor, determining, at the computer system, based on the received data, a location of a tip of a guidewire inserted in a patient, and causing, by the computer system, an indication of the determined location of the tip of the guidewire to be displayed in an overlay image representing at least part of the guidewire.

Abstract: Methods for accurately tracking position and orientation of a magnetic-field sensor in a tracking volume when a large magnetic-field distorter is present in the tracking volume. In some of the methods, magnetic field data is collected from within the tracking volume both with and without the large magnetic-field distorter present in the tracking volume. This data is used to obtain correction information that is subsequently used during real-time operation of the magnetic-field sensor to correct the position and orientation solutions for the sensor for magnetic-field distortions caused by the presence of the large magnetic-field distorter in the tracking volume. Others of the methods involve modeling the large magnetic-field distorter using dipole and multipole modeling. Magnetic tracking systems for implementing the methods include hardware and software for carrying out the methods.

Abstract: Methods for accurately tracking position and orientation of a magnetic-field sensor in a tracking volume when a large magnetic-field distorter is present in the tracking volume. In some of the methods, magnetic field data is collected from within the tracking volume both with and without the large magnetic-field distorter present in the tracking volume. This data is used to obtain correction information that is subsequently used during real-time operation of the magnetic-field sensor to correct the position and orientation solutions for the sensor for magnetic-field distortions caused by the presence of the large magnetic-field distorter in the tracking volume. Others of the methods involve modeling the large magnetic-field distorter using dipole and multipole modeling. Magnetic tracking systems for implementing the methods include hardware and software for carrying out the methods.

Abstract: Lead Tracking of Implantable Cardioverter-Defibrillator and Cardiac Resynchronization Therapy Devices improve upon the process of implantation of ICD-CRT devices, placing their leads, and improving the information fed back to the device and/or clinician. Tracking of the placement of the leads during implantation is accomplished along with monitoring the leads once implanted. Benefits include reducing the risk and complication rate, simplifying implantation procedure, and enabling the extraction of vital data not previously available. Leads are tracked to at least minimize the need to use fluoroscopy. Three dimensional tracking (10) is employed to facilitate obtaining of data that allows the surgeon to better visualize lead insertion and placement. Placement of the leads during a procedure requires use of an external tracking component along with means and method for tracking the implantable leads.

Abstract: An electromagnetic tracking system (600) and a distortion compensation method (500) that utilize a lead-lag network model to compensate for position and orientation distortion caused by eddy currents formed in one or more conductive distorters (330, 658A-C) located within a tracking environment during electromagnetic tracking of one or more objects (612). the method is adaptive relative to the amount of distortion cause by the conductive distorters.

Abstract: A sensor for determining the angular position of a radiating point source in two dimensions includes a mask encoded in two skewed directions with waveforms consisting of several frequencies in prescribed patterns. The frequency spectra of the received detector patterns are computed. In order to facilitate such computations, the constituent frequencies are separated so as to be distinguished in the Fast Fourier Transform (FFT). Each of the frequency patterns that are coded on the variable transmissivity mask consists of a series of low frequencies followed by a series of variable frequencies, and a series of high frequencies. The variable frequencies exhibit frequency changes responsive to various image positions. The low and high frequencies are responsive in phase to variations in image position. The frequency variations in the variable frequencies are used to indicate coarse position while the phases of the fixed low and high frequencies are used to indicate medium and fine position.

Abstract: In a first embodiment, a single linear array of bi-cell optical detectors is arranged with each bi-cell optical detector having a rectangular aperture located a prescribed distance above the surface of the bi-cell optical detector. In the first embodiment, in calculating the position of a point source emitter, it is understood that each detector receives light from the point source emitter at a unique angle different from the angles at which the other detectors receive light from the point source emitter. A plot of detector ratios is made by taking the best fit line through the ratios from each detector and the location of the point where the detector ratio is zero yields the point of perpendicularity between the emitter and the linear detector array. Another embodiment contemplates a three dimensional detector having three linear arrays of bi-cell detectors arranged at the periphery of a measuring space mutually orthogonal to one another.