Intrabody navigation system for medical applications

• US 20030216639A1
• Filed: 04/08/2003
• Published: 11/20/2003
• Est. Priority Date: 08/02/1998
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: superDimension, Ltd. (Medtronic Plc)
• Inventors: Gilboa, Pinhas, Blecher, Danny
• Granted Patent: US 7,555,330 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2072 Reference field transducer attached to an instrument or patient
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: A61B 8/4245 involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient

Abstract

A system and method for tracking the position and orientation of a probe such as a catheter whose transverse inner dimension may be at most about two millimeters. Three planar antennas that at least partly overlap are used to transmit electromagnetic radiation simultaneously, with the radiation transmitted by each antenna having its own spectrum. In the case of single-frequency spectra, the antennas are provided with mechanisms for decoupling them from each other. A receiver inside the probe includes sensors of the three components of the transmitted field, with sensors for at least two of the three components being pairs of sensors, such as coils, disposed symmetrically with respect to a common reference point. In one variant of the receiver, the coils are collinear and are wound about cores that are mounted in pairs of diametrically opposed apertures in the housing of the probe. In another variant of the receiver-catheter combination, the catheter is configured with an inner and outer sleeve connected at their ends by one or more flexible elements on which the coils are mounted. Each member of a pair of coils that sense the same component of the transmitted field is connected to a different input of a differential amplifier. The position and orientation of the receiver relative to the antennas are determined noniteratively, by setting up an overdetermined set of linear equations that relates the received signals to transmitter-receiver amplitudes, solving for the amplitudes and inferring the position coordinates and the orientation angles of the receiver relative to the transmitter from these amplitudes. For the purpose of navigating the probe within the body of a patient, the antennas are rigidly attached to an imaging device such as a fluoroscope, to provide a common frame of reference for both the acquired images of the patient and the measured position and orientation of the receiver. Alternatively, a second receiver is rigidly attached to the imaging device to provide the common frame of reference. In a third alternative, a third receiver is rigidly attached to the patient during imaging, and the mutual positions and orientations of the patient and the imaging device thus measured are used in subsequent navigation of the probe within the body of the patient. An imaging device that includes an electrically conductive surface is provided with a magnetically permeable compensator for minimizing distortion of the transmitted field. A scheme is provided for retrofitting an apparatus such as the receiver to a prior art catheter.

Claims

1. A system for tracking a position and an orientation of a probe, comprising:

(a) a plurality of first sensors, each of said first sensors for detecting a different component of a vector force field, each of said first sensors including two sensor elements disposed symmetrically about a common reference point in the probe, said first sensors being mounted inside the probe.

2. The system of claim 1, wherein said vector force field is an electromagnetic field.

3. The system of claim 1, wherein each of said sensor elements includes a coil.

4. The system of claim 3, wherein, for each of said first sensors, said coils are mutually parallel.

5. The system of claim 3, wherein, for each of said first sensors, said coils are connected in series.

6. The system of claim 5, wherein, for each of said first sensors, said coils have identical helicities.

7. The system of claim 5, wherein, for each of said first sensors, said coils have opposite helicities.

8. The system of claim 3, further comprising:

(b) for at least one of said first sensors;

for each of said coils;

(i) a pair of diametrically opposed apertures in the probe, and

(ii) a core, mounted in said pair of apertures, said each coil being wound about said core.

9. The system of claim 1, including three of said first sensors.

10. The system of claim 9, wherein said sensor elements are collinear.

11. The system of claim 1, further comprising:

(b) a second sensor including a sensor element centered on said common reference point.

12. The system of claim 11, wherein said sensor elements of said first and second sensors are coils.