Receiver used in marker localization sensing system using coherent detection

• US 6,977,504 B2
• Filed: 12/31/2003
• Issued: 12/20/2005
• Est. Priority Date: 12/31/2003
• Status: Active Grant

• Current Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Original Assignee: Calypso Medical Technologies, Inc. (Siemens AG)
• Inventors: Wright, J. Nelson, Newell, Laurence J.
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US10/749,860
• Publication Number:
  US 20050140372A1
• Time in Patent Office: 720 Days
• Field of Search: 324326-329, 324/234, 324/239, 324243-244, 324/260, 600/407, 600/409, 600/410, 600/414, 600/415, 600/420, 600/424
• US Class Current: 324/326
• CPC Class Codes: G01V 15/00 Tags attached to, or associated with, an object, in order to enable detection of the object record carriers for use with machines having a detectable tag or marker G06K19/00

Abstract

A receiver for determining the location of a marker that is excited with an exciting waveform. A sensing array having coils is used to sense magnetic flux from the resonating marker. The coils provide inputs to the receiver. The receiver includes a correlation processor for analyzing the inputs in a coherent manner. The receiver determines the phase component of each of the inputs and compensates for differences.

Claims

1. A system for locating a marker associated with a subject comprising:

an excitation source for emitting an exciting waveform during an excitation interval, said exciting waveform causing said marker to resonate;

a sensing array including a plurality of sensing coils, said sensing coils collectively outputting a plurality of inputs; and

a receiver for analyzing said plurality of inputs to identify and correct a phase shift from said plurality of inputs to implement a coherent receiver.

2. The system of claim 1 wherein said receiver acts on said plurality of inputs gathered during an observation interval.

3. The system of claim 2 wherein said receiver averages multiple sets of said plurality of inputs over a plurality of said observation intervals prior to coherent analysis.

4. The system of claim 1 wherein said exciting waveform is a triangular waveform.

5. The system of claim 1 wherein said excitation source and said sensing coil repeat the emission of said exciting waveform and outputting of said plurality of receiver inputs for a plurality of iterations, said receiver operative to average multiple sets of said plurality of receiver inputs over a plurality of said observation intervals from said plurality of iterations prior to coherent analysis.

6. The system of claim 1 wherein said plurality of inputs are acquired when said excitation source is inactive.

7. The system of claim 1 wherein said receiver includes a quadrature circuit.

8. The system of claim 1 wherein said plurality of inputs are acquired when a radiation source is inactive.

9. The system of claim 5 wherein said exciting waveforms are randomly dithered.

10. The system of claim 1 wherein said phase shift is calculated based upon a least mean squares error of said plurality of inputs.

11. A method for locating a marker associated with a subject comprising:

providing an excitation source for emitting an exciting waveform during an excitation interval, said exciting waveform causing said marker to resonate;

providing a sensing array including a plurality of sensing coils, said sensing coils collectively outputting a plurality of inputs; and

providing a receiver for analyzing said plurality of inputs to identify and correct a phase shift from said plurality of inputs to implement a coherent receiver.

12. The method of claim 11 wherein said receiver acts on said plurality of inputs gathered during an observation interval.

13. The method of claim 12 wherein said receiver averages multiple sets of said plurality of inputs over a plurality of said observation intervals prior to coherent analysis.

14. The method of claim 11 wherein said exciting waveform is a triangular waveform.

15. The method of claim 11 further including repeatiung the emission of said exciting waveform and outputting of said plurality of receiver inputs for a plurality of iterations, said receiver operative to average multiple sets of said plurality of receiver inputs over a plurality of said observation intervals from said plurality of iterations prior to coherent analysis.

16. The method of claim 11 wherein said plurality of inputs are acquired when said excitation source is inactive.

17. The method of claim 11 wherein said receiver includes a quadrature circuit.

18. The method of claim 11 wherein said plurality of inputs are acquired when a radiation source is inactive.

19. The method of claim 15 wherein said exciting waveforms are randomly dithered.

20. The method of claim 11 wherein said phase shift is calculated based upon a least mean squares error of said plurality of inputs.