Method and apparatus for detection of air cavities in a body

• US 20020151789A1
• Filed: 06/05/2002
• Published: 10/17/2002
• Est. Priority Date: 03/30/1998
• Status: Active Grant

• Current Assignee: Rush-Presbyterian St Luke's Medical Center Incorporated (Rush University)
• Original Assignee: Rush-Presbyterian St Luke's Medical Center Incorporated (Rush University)
• Inventors: Sandler, Richard H., Mansy, Hussein A.
• Granted Patent: US 6,595,928 B2
• Time in Patent Office: Days
• US Class Current: 600/431
• 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 8/485 involving measuring strain or elastic properties

Abstract

A method and apparatus for detecting the presence of gas cavities in the abdomen, the thorax and elsewhere is disclosed. The apparatus includes an actuator for transmitting low frequency vibro-acoustic waves (such as from a white noise generator, impulse wave or chirp signal) into the body at a first location and a detector (such as from a vibro-acoustic sensor, microphone, air-coupled microphone or optical detector) for receiving the transmitted low frequency vibro-acoustic waves at a second location on the body. The actuator and detector are positioned to be effective for detecting the suspected gas cavity. The detector generates a response signal which is analyzed. Resonance waves and anti-resonance waves in the detected signal indicate the presence of a gas cavity.

Claims

1. Apparatus for detecting the presence of a gas cavity in a desired region of a body comprising:

a source of low frequency vibro-acoustic waves positioned at a first location on the body for transmitting low frequency vibro-acoustic waves into the desired region of the body;

a detector positioned at a second location on the body for receiving the transmitted low frequency vibro-acoustic waves and for generating a signal representative of the frequency response of the body resulting from the presence of any gas cavity therein; and

a processor for analyzing the frequency response and for detecting the presence of resonance waves and anti-resonance waves indicative of the presence of any gas cavity therein.

2. The apparatus of claim 1 wherein the source comprises an actuator transmitting vibro-acoustic waves at a frequency from 5 Hz to 2000 Hz.

3. The apparatus of claim 1 wherein the detector comprises at least one vibro-acoustic sensor.

4. The apparatus of claim 1 wherein the detector comprises a microphone.

5. The apparatus of claim 1 wherein the detector comprises an air-coupled microphone.

6. The apparatus of claim 1 wherein the detector comprises an optical detector.

7. The apparatus of claim 1 wherein the body comprises a human body and the desired region comprises the peritoneal cavity.

8. The apparatus of claim 1 wherein the body comprises a human body and the desired region comprises the thorax cavity.

9. The apparatus of claim 1 wherein the first and second locations are chosen to be effective for detection of any cavity within the desired region.

10. The apparatus of claim 1 wherein the first and second locations are chosen to maximize detection of any cavity within the desired region.

11. The apparatus of claim 1 wherein the source comprises a white noise source transmitting vibro-acoustic waves at a frequency from 5 Hz to 2000 Hz.

12. The apparatus of claim 1 wherein the source comprises an impulse source transmitting an impulse wave at a frequency from 5 Hz to 2000 Hz.

13. The apparatus of claim 1 wherein the source comprises a chirp signal.

14. The apparatus of claim 1 wherein the source comprises a swept frequency signal.

15. The apparatus of claim 1 wherein the source comprises at least a pair of discrete frequency signals.

16. The apparatus of claim 1 wherein the detector comprises a plurality of sensors positioned at different locations around the desired region.

17. The apparatus of claim 1 wherein the body comprises an animal body and the desired region comprises the peritoneal cavity.

18. The apparatus of claim 1 wherein the body comprises an animal body and the desired region comprises the thorax cavity.

20. The method of claim 19 wherein the analyzing step includes the steps of:

calculating a transfer function of the frequency response signal; and

examining the transfer function morphology.

21. The method of claim 20 wherein the step of calculating the transfer function includes the steps of:

calculating the spectrum of the source of low frequency vibro-acoustic waves (S_in.

calculating the spectrum of the detected low frequency vibro-acoustic waves (S_out.;

wherein the transfer function is equal to the ratio of S_in to S_out.

22. The method of claim 20 wherein the step of examining the transfer function includes the steps of:

smoothing the transfer function with a moving average filter.

23. The method of claim 20 further comprising the step of determining the frequency and spectral amplitude of the resonance (F_r, S_r. and anti-resonance of the response signal (F_ar, S_ar.

24. The method of claim 23 further comprising the step of determining if F_r is between a predetermined minimum and maximum value.

25. The method of claim 23 further comprising the step of determining if F_ar is between a predetermined minimum and maximum value.

26. The method of claim 23 further comprising the step of determining if the ratio of S_r/S_ar is between a predetermined minimum and maximum value.

27. The method of claim 19 further comprising the step of positioning the detector at a third location to enhance the resonance portion of the response signal and to diminish the anti-resonance portion of the response signal.

29. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises an actuator transmitting vibro-acoustic waves at a frequency from 5 Hz to 2000 Hz.

30. The apparatus of claim 28 wherein the means for detecting the transmitted low frequency vibro-acoustic waves comprises an air-coupled microphone.

31. The apparatus of claim 28 wherein the detector comprises at least one vibro-acoustic sensor.

32. The apparatus of claim 28 wherein the detector comprises a microphone.

33. The apparatus of claim 28 wherein the detector comprises an optical detector.

34. The apparatus of claim 28 wherein the body comprises a human body and the desired region comprises the peritoneal cavity.

35. The apparatus of claim 28 wherein the body comprises a human body and the desired region comprises the thorax cavity.

36. The apparatus of claim 28 wherein the first and second locations are chosen to be effective for detection of any cavity within the desired region.

37. The apparatus of claim 28 wherein the first and second locations are chosen to maximize detection of any cavity within the desired region.

38. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises a white noise source transmitting vibro-acoustic waves at a frequency from 5 Hz to 2000 Hz.

39. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises an impulse source transmitting an impulse wave at a frequency from 5 Hz to 2000 Hz.

40. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises a chirp signal.

41. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises a swept frequency signal.

42. The apparatus of claim 28 wherein the means for transmitting low frequency vibro-acoustic waves comprises at least a pair of discrete frequency signals.

43. The apparatus of claim 28 wherein the body comprises an animal body and the desired region comprises the peritoneal cavity.

44. The apparatus of claim 28 wherein the body comprises an animal body and the desired region comprises the thorax cavity.

19. A method of detecting the presence of a gas cavity in a desired region of a body comprising the steps of:

positioning a source of low frequency vibro-acoustic waves at a first location on the body;

positioning a detector at a second location of the body;

transmitting low frequency vibro-acoustic waves into the first location of the body;

detecting the transmitted low frequency vibro-acoustic waves at the second location on the body;

generating a signal representative of the frequency response of the body resulting from the presence of any gas cavity therein;

analyzing the frequency response signal; and

detecting the presence of peaks in the response signal indicative of resonance waves and detecting the presence of dips in the response signal indicative of anti-resonance waves.

28. Apparatus for detecting the presence of a gas cavity in a desired region of a body comprising the steps of:

means for transmitting low frequency vibro-acoustic waves into a first location of the body;

means for detecting the transmitted low frequency vibro-acoustic waves at a second location on the body;

means for generating a signal representative of the frequency response of the body resulting from the presence of any gas cavity therein;

means for analyzing the frequency response signal; and

means for detecting the presence peaks in the response signal indicative of resonance waves and detecting the presence of dips in the response signal indicative of anti-resonance waves.