Magnetic catheter tracker and method therefor
First Claim
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1. A method of tracking an object within a volume, the method comprising steps of:
- coupling a rotating permanent magnet to said object;
measuring magnetic fields produced by the rotating permanent magnet remotely or on the surface of or exterior to the volume, to produce measurements; and
based on said measurements, determining a position and an orientation of the rotating permanent magnet and a position and orientation of said object to which said permanent magnet is coupled comprising;
inputting said measurements to a processor, said measurements comprising signals representing values of the magnetic fields;
filtering said signals to produce filtered signals;
digitizing said filtered signals;
recording a reference signal from the rotating permanent magnet synchronously with the rotating magnetic dipole;
performing a direct current (DC) level shift of said digitized signals and the reference signal to reduce an offset from zero of an average magnetic field and produced a level-shifted value; and
performing a digital lock-in operation based on said level-shifted value.
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Abstract
A method, apparatus, and system for tracking an object within a volume, includes coupling a rotating magnetic dipole to the object, measuring the magnetic fields either remotely, on the surface of, or exterior to the volume, to produce measurements; and based on the measurements, determining the position and the orientation of the magnetic dipole, thereby to determine a position and orientation of the object.
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Citations
10 Claims
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1. A method of tracking an object within a volume, the method comprising steps of:
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coupling a rotating permanent magnet to said object; measuring magnetic fields produced by the rotating permanent magnet remotely or on the surface of or exterior to the volume, to produce measurements; and based on said measurements, determining a position and an orientation of the rotating permanent magnet and a position and orientation of said object to which said permanent magnet is coupled comprising; inputting said measurements to a processor, said measurements comprising signals representing values of the magnetic fields; filtering said signals to produce filtered signals; digitizing said filtered signals; recording a reference signal from the rotating permanent magnet synchronously with the rotating magnetic dipole; performing a direct current (DC) level shift of said digitized signals and the reference signal to reduce an offset from zero of an average magnetic field and produced a level-shifted value; and performing a digital lock-in operation based on said level-shifted value. - View Dependent Claims (2, 3, 4)
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5. A system for tracking an object in a volume, comprising:
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a rotating permanent magnet coupled to said object; at least two detectors for measuring magnetic fields exterior to the volume produced by said rotating permanent magnet, to produce measurements; a determining unit for determining, based on said measurements, a position of the permanent magnet and a position of said object to which said permanent magnet is coupled; a bandpass filter for filtering outputs from said at least two detectors, thereby providing a band pass around a rotational frequency of the permanent magnet, a filter being provided corresponding to each said at least two detectors; and an analog-to-digital (A/D) converter for converting filtered outputs from said filter to digital values representing the magnetic fields, said digital values being inputted into said determining unit, said determining unit comprising a computer. - View Dependent Claims (6, 7)
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8. A system for tracking an object in a volume, comprising:
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a rotating permanent magnet coupled to said object; a detector for measuring magnetic fields exterior to the volume produced by said rotating permanent magnet, to produce measurements; and a determining unit for determining, based on said measurements, a position of the permanent magnet and a position of said object to which said permanent magnet is coupled comprising; means for recording a reference signal from the rotating permanent magnet synchronously with the rotating permanent magnet; a direct current (DC) level shifter for shifting a level of said digitized signals and the reference signal, to reduce an offset from zero of an average magnetic field and produced a level-shifted value; and a digital lock-in unit for performing a digital lock-in operation based on said level-shifted value. - View Dependent Claims (9, 10)
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Specification