Magnetic resonance scanner with electromagnetic position and orientation tracking device

• US 20050146327A1
• Filed: 02/28/2005
• Published: 07/07/2005
• Est. Priority Date: 12/23/1998
• Status: Active Grant

• Current Assignee: Peter D. Jakab
• Original Assignee: Peter D. Jakab
• Inventors: Jakab, Peter D.
• Granted Patent: US 7,081,748 B2
• Time in Patent Office: Days
• US Class Current: 324/302
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR

Abstract

A system for combining electromagnetic position and orientation tracking with magnetic resonance scanner is provided. One embodiment includes a magnetic resonance scanner defining a reference coordinate system for scanning a target. Coupled to the magnetic resonance scanner is a magnetic field source which produces a magnetic field. The magnetic field is sensed by a magnetic field sensor which produces a signal proportional to the magnetic field. The magnetic field sensor has a location relative to the reference coordinate system. The location of the magnetic field sensor relative to the reference coordinate system of the magnetic resonance scanner is determined by a location tracking device using at least a line segment model of the magnetic field source and the signal from the magnetic field sensor.

Claims

1. A system comprising:

a magnetic field source generating a spatially distinct magnetic field from a source signal;

a magnetic field sensor sensing a sensed magnetic field; and

a processor receiving a sensor signal from the magnetic field sensor, wherein the processor calculates a position and orientation of the magnetic field sensor relative to the magnetic field source, from;

a) a magnetic field source model;

b) a representation of the source signal from the magnetic field source;

c) a magnetic field sensing model;

d) a representation of the sensor signal from the magnetic field sensor;

wherein the magnetic field source model includes a representation of tangible elements of the magnetic field source and a representation of tangible magnetically coupled elements which contribute to the sensed magnetic field.

2. The system according to claim 1, wherein the processor provides a signal representative of the position and orientation of the magnetic field sensor to an output.

3. The system according to claim 1, wherein the magnetic field source and the magnetic field sensor include a number of tangible elements such that the number of possible independent measurements exceeds the minimum number required to determine the position and orientation of the magnetic field sensor;

and

the processor;

collects at least the minimum number of independent measurements to calculate a value for the tangible magnetically coupled elements of the magnetic field source model and the magnetic field sensing model.

4. The system according to claim 1, wherein a second sensor provides a number of tangible elements such that the number of possible independent measurements exceeds the minimum number required to determine the position and orientation of the first and second magnetic field sensors.

5. The system according to claim 1, wherein the processor uses a line segment model for the magnetic field source model.

6. The system according to claim 1, wherein at least one magnetic field sensor is attached to at least one moveable object and the processor calculates the position and orientation of the at least one moveable object relative to the magnetic field source.

7. The system according to claim 6, wherein a magnetic resonance scanner is included for scanning a target.

8. The system according to claim 7, wherein the magnetic field source is coupled to a magnet assembly of the magnetic resonance scanner.

9. The system according to claim 8, wherein the magnetic resonance scanner further includes a gradient magnetic field generating element for scanning the target and the gradient magnetic field generating element also utilized as the magnetic field source.

10. The system according to claim 8, wherein the magnetic resonance scanner outputs a scan data set representative of an area of the target for the processor and the processor combines the scan data set with the position and orientation of the moveable object creating an output.

11. The system according to claim 10, wherein the output is displayed on a display device.

12. The system according to claim 10, further comprising:

a third magnetic field sensor is attached to the magnet assembly of the magnetic resonance scanner, instead of the magnetic field source.

13. The system according to claim 12, further comprising:

a fourth magnetic field sensor coupled to the target, wherein the position and orientation tracking device is capable of tracking the position and orientation of the target relative to the magnet assembly of the magnetic resonance scanner.

14. A method for determining the position and orientation of a magnetic field sensor relative to a magnetic field source, comprising:

generating a spatially distinct magnetic field from a source signal with a magnetic field source;

providing a sensor signal proportional to a sensed magnetic field from a sensor to a processor; and

calculating a position and orientation of the magnetic field sensor relative to the magnetic field source with the processor, from;

a magnetic field source model;

the source signal;

a magnetic field sensing model;

the sensor signal; and

wherein the magnetic field source model includes a representation of tangible elements of the magnetic field source and representations of a tangible magnetically coupled elements which contribute to the sensed magnetic field.

15. The method according to claim 14, further comprising:

providing a signal representative of the position and orientation of the magnetic field sensor to an output.

16. The method according to claim 14, wherein the processor collects independent measurements in excess of the minimum required to compute the position and orientation of the magnetic field sensor relative to the magnetic field source, and uses the measurements also to redefine the tangible magnetically coupled elements of the magnetic field source model and the magnetic field sensing model to achieve better accuracy.

17. The method according to claim 16, wherein the magnetic field source and the magnetic field sensor include a number of tangible elements such that the number of possible independent measurements exceeds the minimum number required to determine the position and orientation of the magnetic field sensor.

18. The method according to claim 16, wherein a second sensor provides a number of tangible elements such that the number of possible independent measurements exceeds the minimum number required to determine the position and orientation of the first and second magnetic field sensors.