Optimal drive frequency selection in electrical tomography

• US 7,969,161 B2
• Filed: 12/01/2009
• Issued: 06/28/2011
• Est. Priority Date: 12/02/2008
• Status: Expired due to Fees

• Current Assignee: Proteus Digital Health, Inc. (Otsuka Holdings Company Limited)
• Original Assignee: Proteus Bomedical Incorporated
• Inventors: Behzadi, Yashar, Crandall, Kenneth C.
• Primary Examiner(s): Dole; Timothy J
• Application Number:
  US12/665,514
• Publication Number:
  US 20110001488A1
• Time in Patent Office: 574 Days
• Field of Search: 324/613, 324/614, 600/547
• US Class Current: 324/613
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/415 the glands, e.g. tonsils, adenoids or thymus
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

Electrical tomography drive frequency selection systems and methods are disclosed. One aspect of the present invention pertains to a system for optimally selecting a drive frequency of an electrical tomography which comprises a sensor electrode stably associated with a tissue site within an internal organ of a subject for generating an induced signal based on a noise signal over a range of frequency bands, wherein an electrical field for the electrical tomography is turned off. In addition, the system comprises a noise processing module for isolating the induced signal for each frequency band over the range of frequency bands. Furthermore, the system comprises a frequency select module for selecting a drive frequency of the electrical field for the electrical tomography by comparing the induced signal for each frequency band over the range of frequency bands.

Claims

1. A system for optimally selecting a drive frequency of an electrical tomography, comprising:

a sensor electrode implanted at a tissue site of a subject to generate an induced signal based on a noise signal over a range of frequency bands, wherein an electrical field for the electrical tomography is turned off;

a noise processing module to separate the induced signal for each frequency band over the range of frequency bands; and

a frequency select module to select a drive frequency of the electrical field for the electrical tomography by comparing the induced signal for each frequency band over the range of frequency bands.

2. The system of claim 1, wherein the range of frequency bands is between 50 KHz and 150 KHz.

3. The system of claim 1, wherein a bandwidth of each frequency band comprises 100 Hz.

4. The system of claim 1, wherein the sensor electrode is coupled to the noise processing module via an electrical lead.

5. The system of claim 1, wherein the noise processing module comprises a spectrum analyzer.

6. The system of claim 5, wherein the spectrum analyzer is operable for performing a Fast Fourier Transform of the induced signal.

7. The system of claim 1, wherein the selecting the drive frequency of the electrical field comprises selecting a frequency band with a minimal instantaneous amplitude among the frequency bands.

8. The system of claim 1, wherein the sensor electrode comprises a quadrature amplitude modulator.

9. The system of claim 8, wherein the noise processing module comprises a quadrature amplitude demodulator.

10. The system of claim 9, wherein the quadrature amplitude demodulator comprises a first mixer and a first low pass filter coupled in series to demodulate an in-phase modulated signal (I) and a second mixer and a second low pass filter to demodulate a quadrature-phase modulate signal (Q).

11. The system of claim 10, wherein the noise processing module further comprises a frequency oscillator coupled to the first mixer and the second mixer to sweep across the range of frequency bands.

12. The system of claim 11, wherein the selecting the drive frequency of the electrical field comprises selecting a frequency band with a minimal instantaneous amplitude among the frequency bands.

13. The system of claim 1, wherein the noise processing module comprises a plurality of band pass filters for processing the range of frequency bands.

14. The system of claim 13, wherein the selecting the drive frequency of the electrical field comprises selecting a frequency band with a minimal instantaneous amplitude among respective outputs of the plurality of band pass filters.

15. The system of claim 1, further comprising an electrical field generator module to generate the electrical field with the drive frequency.

16. The system of claim 1, wherein the electrical field is based on a sinusoidal wave.

17. The system of claim 1, wherein the electrical field is based on a spread spectrum signal.

18. A method for optimally selecting a drive frequency of an electrical tomography system, comprising:

scanning for noise signal processed by a sensor electrode internally located at a tissue site of the electrical tomography system over a range of frequency bands prior to applying an electrical field of the electrical tomography system to the sensor electrode;

comparing the noise signal processed by the sensor electrode over the range of frequency bands; and

selecting a frequency band with a minimal noise signal among the range of frequency bands as the drive frequency of the electrical tomography system.

19. The method of claim 18, wherein the noise signal is transmitted via an electrical lead.

20. The method of claim 19, wherein the scanning for the noise signal comprises performing a Fast Fourier Transform of the noise signal accessed at the electrical lead.

21. The method of claim 19, wherein the scanning for the noise signal comprises performing a Discrete Fourier Transform of the noise signal.

22. The method of claim 19, wherein the scanning for the noise signal comprises analyzing energy contents of the range of the frequency bands.

23. The method of claim 18, wherein the range of frequency bands is between 50 KHz and 150 KHz.

24. The method of claim 18, wherein a bandwidth of each frequency band comprises 100 Hz.

25. The method of claim 18, wherein the selecting the drive frequency of the electrical tomography system is performed periodically.

26. The method of claim 18, wherein the electrical field of the drive frequency is based on a sinusoidal wave.

27. The method of claim 18, wherein the electrical field of the drive frequency is based on a spread spectrum signal.

28. A non-transitory computer readable medium for optimally selecting a drive frequency of an electrical tomography system having instructions that, when executed by a computer, cause the computer to perform a method comprising:

scanning for noise signal processed by a sensor electrode, which is implanted at a tissue site, of an electrical tomography system over a range of frequency bands prior to applying an electrical field of the electrical tomography system to the sensor electrode;

comparing the noise signal processed by the sensor electrode over the range of frequency bands; and

selecting a frequency band with a minimal noise signal among the range of frequency bands as the drive frequency of the electrical tomography system.

29. A system for selecting a drive frequency of an electrical tomography, comprising:

a sensor electrode implanted at an internal tissue site of a subject to generate a signal through induction, wherein the signal represents the power level of a noise signal over a range of frequency bands when an electrical field used to produce the electrical tomography is turned off;

a noise processing module to separate the signal for each frequency band over the range of frequency bands; and

a frequency select module to select a drive frequency of the electrical field for the electrical tomography by comparing the signal for each frequency band over the range of frequency bands.