PERCUTANEOUS NEPHROLITHOTOMY TARGET FINDING SYSTEM

• US 20140051985A1
• Filed: 06/10/2013
• Published: 02/20/2014
• Est. Priority Date: 08/17/2012
• Status: Abandoned Application

• Current Assignee: Gyrus Acmi (Olympus Corporation)
• Original Assignee: Gyrus Acmi (Olympus Corporation)
• Inventors: Fan, Tailin, Cook, Christopher A.
• Application Number:
  US13/913,649
• Publication Number:
  US 20140051985A1
• Time in Patent Office: Days
• US Class Current: 600/424
• CPC Class Codes: A61B 1/00004 characterised by electronic signal processing
• CPC Class Codes: A61B 1/00158 using magnetic field
• CPC Class Codes: A61B 1/307 for the urinary organs, e.g. urethroscopes, cystoscopes
• CPC Class Codes: A61B 17/3403 Needle locating or guiding means guides for suture needles A61B17/0482; guiding or tracking by nuclear magnetic resonance G01R33/285
• CPC Class Codes: A61B 2034/2048 using an accelerometer or inertia sensor
• 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 5/062 using magnetic field

Abstract

A target finding system identifies a surgical target such as a kidney stone by disposing an emitter such as a magnetic source behind or adjacent the surgical target, and employing a circuit to identify an axis to the emitter, thus defining an axis or path to the surgical target. An array of sensors arranged in an equidistant, coplanar arrangement each senses a signal indicative of a distance to the emitter. A magneto resistor sensor generates a variable resistance is responsive to the distance to a magnetic coil emitting a magnetic field. An equal signal from each of the coplanar sensors indicates positioning on an axis passing through a point central to the sensors and orthogonal to the plane. In one embodiment, a pair of Wheatstone bridges enhances the accuracy of the system.

Claims

1. A target finding system, comprising:

an internal target object (ITO) disposed at an end of an endoscope providing an electromagnetic signal;

an external target finder (ETF) comprising;

a needle guide aperture; and

at least four sensors arranged symmetrically around the needle guide aperture, the sensors configured to receive the electromagnetic signal from the ITO;

a detector coupled to the at least four sensors to determine an orientation and a position of a needle guide aperture relative to the ITO; and

a user interface connected to the ETF to indicate the orientation and the position of the needle guide aperture relative to the ITO.

2. The system of claim 1, wherein each of the at least four sensors comprise a magnetic sensor connected in at least one measuring bridge circuit and the detector and the user interface comprises an analog circuit.

3. The system of claim 1, wherein the ITO comprises a first magnetic source.

4. The system of claim 3, wherein the first magnetic source comprises one of:

a static magnetic field provided by a permanent magnet; and

a varying magnetic field provided by a current carrying coil.

5. The system of claim 4, wherein the endoscope further comprises:

a second magnetic source; and

wherein one of the first magnetic source and the second magnetic source is a switchable magnetic source.

6. The system of claim 4, further comprising a digital signal processor coupled to the at least four sensors and the user interface.

7. The system of claim 1, wherein the endoscope is a ureteroscope.

8. The system of claim 1, wherein each of the at least four sensors comprises a plurality of solid state detectors configured in a multi-dimensional array.

9. The system of claim 1, wherein the needle guide comprises at least one sensor disposed thereon to provide a location and an orientation of a needle disposed within the needle guide.

10. The system of claim 1, wherein the at least four sensors are disposed coplanar in a first plane and configured in a first Wheatstone bridge having a first sensing plane;

and

further comprising a second Wheatstone bridge disposed in a second plane parallel to the first plane having a second sensing plane perpendicular to the first sensing plane.

11. A method of finding a target comprising:

providing a first magnetic source disposed at an end of an endoscope and having an electromagnetic signal in a vicinity of a target;

detecting the electromagnetic signal using a sensor array having at least four sensors arranged in a bridge configuration;

determining a position and orientation of a needle guide aperture relative to the target; and

indicating the position and orientation of the needle guide aperture relative to the electromagnetic signal in the vicinity of the target.

12. The method of claim 11 further comprising comparing a relative strength of the electromagnetic signal received by each of the at least four sensors in the sensor array using at least one measuring bridge circuit.

13. The method of claim 12 further comprising determining an orientation of a center axis of the electromagnetic signal with respect to two orthogonal planes of the sensor array.

14. The method of claim 12 further comprising detecting a field gradient to find a relative distance and directionality between the electromagnetic signal and a plane of the sensor array.

15. The method of claim 11 further comprising:

providing a second switchable magnetic source disposed on the endoscope, separated from the first magnetic source;

detecting separate electromagnetic signals from each of the first and second magnetic sources; and

determining an orientation of a front face of the endoscope.

16. The method of claim 11 further comprising:

providing an additional sensor on the needle guide; and

determining when a needle inserted through needle guide is within a predetermined close proximity of the target.

17. The method of claim 16 wherein in the needle guide aperture is movable within a detector plate;

detecting one of;

a needle tip position; and

a needle trajectory; and

detecting the position of the needle.

18. The method of claim 11 further comprising:

detecting a change in the electromagnetic signal when a needle inserted through needle guide approaches the target; and

determining when the needle is within a predetermined close proximity of the target.

19. The method of claim 11 further comprising adapting the needle guide to perform a percutaneous nephrolithotomy (PCNL) procedure.

20. The method of claim 11 wherein the sensor array comprises:

a first Wheatstone bridge in a first plane having a first zero-output plane;

a second Wheatstone bridge disposed in a second plane parallel to the first plane having a second zero-output plane perpendicular to the first zero-output plane;

the method further comprising determining when a center axis of the electromagnetic signal is aligned with an intersection of a first zero-output plane and a second zero-output plane of the needle guide aperture by;

detecting when the center axis is in the first zero-output plane using the first Wheatstone bridge; and

detecting when the center axis is in the second zero-output plane using the second Wheatstone bridge.