Microwave method and system to detect and locate cancers in heterogenous tissues

• US 5,829,437 A
• Filed: 05/02/1996
• Issued: 11/03/1998
• Est. Priority Date: 07/01/1994
• Status: Expired due to Term

• Current Assignee: Interstitial, LLC
• Original Assignee: Interstitial, Inc.
• Inventors: Bridges, Jack E.
• Primary Examiner(s): Casler, Brian L.
• Application Number:
  US08/641,834
• Time in Patent Office: 915 Days
• Field of Search: 128/653.1, 324/637, 324/638, 324/639, 607/89, 607/101, 600/10, 600/12, 606/27, 606/33-45
• US Class Current: 600/430
• 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 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 6/0435 with means for imaging suspended breasts
• CPC Class Codes: A61B 6/502 for diagnosis of breast, i.e. mammography
• CPC Class Codes: A61B 6/508 for non-human patients

Abstract

A method and system for detecting an incipient tumor in living tissue such as that of a human breast in accordance with differences in relative dielectric characteristics. A generator produces a non-ionizing electromagnetic input wave of preselected frequency, usually exceeding three gigahertz, and that input wave is used to irradiate the living tissue, being effectively focused into a minute, discrete volume within the tissue to develop a non-ionizing electromagnetic wave at that position. The illumination location is shifted over a portion of the living tissue in a predetermined scanning pattern. Backscatter signal returns from the living tissue are collected to develop a backscatter return signal wave. The backscatter wave is processed to segregate skin tissue backscatter to develop a segregated backscatter wave signal; that segregated signal, in turn, is employed to detect any anomaly, caused by differences in relative dielectric characteristics, that is indicative of the presence of a tumor or other abnormality in the scanned living tissue.

Claims

1. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as the tissue of a human breast, wherein normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality, and wherein surface tissue such as skin has a different dielectric characteristic than the normal tissue, the method comprising:

A. generating a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

B. applying the input wave of step A to a radiating antenna in contact with the skin of a living organism to illuminate a minute, discrete volume at a predetermined position within the tissue of the living organism and develop a backscatter wave from that volume;

C. collecting a preselected portion of the backscatter wave developed by step B with a collecting antenna in contact with the surface tissue of the living organism to develop a secondary backscatter wave that includes surface tissue backscatter; and

D. processing the secondary backscatter wave of step C to separate surface tissue backscatter from the secondary backscatter wave and develop a segregated backscatter wave and detect an abnormality in the tissue.

2. A non-invasive method of detecting an abnormality in living tissue, according to claim 1, in which the radiating antenna of step B is also used as the collecting antenna of step C.

3. A non-invasive method of detecting an abnormality in living tissue, according to claim 1, in which, in step B, the input wave is applied to the radiating antenna through an input waveguide having a controllable time delay characteristic.

4. A non-invasive method of detecting an abnormality in living tissue, according to claim 1, and including the following step:

C1. delaying the second backscatter wave prior to processing in step D.

5. A non-invasive method of detecting an abnormality in living tissue, according to claim 4, and including the following steps:

E. repeating steps B, C, C1 and D for a second minute, discrete volume within the tissue of the organism.

6. A non-invasive method of detecting an abnormality in living tissue, according to claim 5, and including the following steps:

F. applying additional time delay to the segregated backscatter waves of steps D;

G. combining the delayed backscatter waves of step F; and

H. varying a time delay of at least one of the previous method steps to enhance the backscatter waves.

7. A non-invasive method of detecting an abnormality in living tissue, according to claim 6, in which, in step G, phase characteristics are varied to control time delay.

8. A non-invasive method of detecting an abnormality in living tissue, according to claim 1, in which, in step C, the collecting antenna is connected to a return waveguide having a controllable time delay characteristic.

9. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as the tissue of a human breast, wherein normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality or other tissue types, and wherein surface tissue, such as skin and other near-surface tissue, have a different dielectric characteristic than the normal tissue, the method comprising:

I. generating a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

J. applying the input wave of step I to a radiating antenna in contact with the skin of a living organism to illuminate an adjacent small volume of the near-surface tissues within the living organism and develop a scattered wave from that volume;

K. collecting a preselected portion of the scattered wave developed in step J with a collecting antenna in contact with the near-surface tissue of the living organism to develop a secondary scattered wave;

L. processing the secondary scattered wave of step K to develop a dielectric characterization of the near-surface tissue; and

M. utilizing the dielectric characterization of the near-surface tissues from step L to compensate for perturbations introduced into scattered returns by the near-surface tissues and detect an abnormality in the tissue.

10. A non-invasive method of detecting an abnormality in living tissue, according to claim 9, in which the radiating antenna of step J is also used as the collecting antenna of step K.

11. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 9, in which the near-surface tissue, in steps K, L and M, is the skin.

12. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 9, in which the near-surface tissue, in steps K, L and M, is the skin and adjacent normal tissue.

13. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as the tissue of a human breast, wherein normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality or other tissue types, and wherein surface tissue, such as skin, has a different dielectric characteristic than the normal tissue, the method comprising:

N. generating a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

O. applying the input wave of step A to an array of radiating antennas in contact with the surface of a living organism to illuminate minute, discrete volumes at predetermined positions within the tissue of the living organism and develop a series of scattered waves from these discrete volumes;

P. collecting preselected portions of the scattered waves developed in step O with an array of collecting antennas in contact with the surface tissue of the living organism to develop a series of secondary scattered waves from these discrete volumes;

Q. processing each of the secondary scattered waves of step P to separate surface tissue backscatter from the secondary scattered waves and develop a series of segregated scattered waves; and

R. shifting a timing of each of the segregated scattered waves such that the segregated scattered returns combine constructively for a preselected volume and detecting an abnormality in the tissue.

14. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 13, in which step Q includes the sub-step of determining the dielectric characteristics of tissue just below the surface tissue near selected antennas, and including the following additional step:

S. modifying the time shift for each of the segregated scattered waves, step R, according to a propagation time developed from the measured dielectric characteristics of the near-surface tissues.

15. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 13, including the following additional step:

T. using the scattered returns from a known scattering source to enhance the combined scattered segregated waves from a preselected location.

16. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 15, in which the preselected location is a portion of the rib cage.

17. A non-invasive method of detecting an abnormality in living tissue, according to claim 13, in which the radiating antenna of step 0 is also used as the collecting antenna of step P.

18. A non-invasive method of detecting an abnormality in living tissue, according to claim 13, in which, in step R, the time shift for the scattered returns is introduced by waveguides that have controllable time delays.

19. A non-invasive method of detecting an abnormality in living tissue, according to claim 13, in which the time shifts for the scattered returns required in Step R are introduced in a digital processing unit employed for Step Q.

20. A non-invasive method of detecting an abnormality in living tissue, according to claim 13, in which the time shifts for the scattered returns required in Step R are introduced by a function that modifies a phase relationships in steps O, P and Q.

21. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as the tissue of a human breast, wherein normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality or other tissue, and wherein surface tissue, such as skin, has a different dielectric characteristic than the normal tissue, the method comprising:

V. generating a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

W. applying the input wave of step V to a radiating antenna that is progressively repositioned on surface tissue of a living organism to illuminate minute, discrete volumes at predetermined positions within the tissue of the living organism and develop a series of scattered waves from those volume;

X. collecting a preselected portion of the scattered waves developed by step W by a collecting antenna that is progressively repositioned on the surface tissue of the living organism to develop a series of secondary scattered waves from each collecting position that includes surface tissue scattered waves;

Y. processing each of the secondary scattered waves of step X to separate surface tissue scatter from the secondary scattered waves and develop a series of segregated scattered waves; and

Z. shifting a timing of each of the segregated scattered waves such that the scattered returns from a preselected volume combine constructively and detecting an abnormality in the tissue.

22. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21, in which step Y includes the sub-step of determining the dielectric characteristics of the tissue just below the surface tissue;

and

AA. modifying the timing of each of the segregated scattered waves according to a propagation time developed from the measured dielectric characteristics of near surface tissues to enhance the combined returns from a preselected volume.

23. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 22, and further comprising:

BB. using the scattered returns from a known scattering source to further the timing of each of the segregated waves from each of the preselected locations.

24. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 23, in which the preselected location is a portion of the rib cage.

25. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21, in which the radiating antenna array of step W is the same as the collecting antenna array of step X.

26. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21, in which, in step Z, the time shifts for the scattered returns are introduced by waveguides that have controllable time delays.

27. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21, in which, in step Z, the time shifts for the scattered returns are introduced in a digital processing unit employed for step Y.

28. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21, in which, in step Z, the time shifts for the scattered returns are introduced by a function that modifies phase relationships in steps W, X and Y.

29. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21 wherein in step W the radiating antenna remains in a fixed position.

30. A non-invasive method of detecting the presence of an abnormality in the tissue of a living organism, according to claim 21 wherein in step X the collecting antenna remains in a fixed position.

31. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as a tumor on the prostate gland, wherein the normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality or other tissue, and wherein surface tissue near the gland, such as the lining of the rectum, has a different dielectric characteristic than the normal tissue, the method comprising:

EE. generating a non-ionizing electromagnetic input wave within a preselected side band frequency range;

FF. applying the input wave of step EE to a radiating antenna positioned on surface tissue of a living organism such that the input wave preferentially illuminates a preselected volume within the tissue of the living organism and develops scattered waves from that volume;

GG. collecting scattered waves from the preselected volume of step FF by a collecting antenna that is positioned on the surface tissue of the living organism to develop a series of secondary scattered waves that include surface tissue scattered waves;

II. processing each of the secondary scattered waves of step GG to separate surface tissue scatter from the secondary scattered waves and develop a series of segregated scattered waves; and

KK. combining the segregated scattered waves of step II in a display that shows the position of abnormalities in the tissue.

32. A non-invasive method of detecting an abnormality in the tissue of a living organism, according to claim 31, in which the radiating antenna of step FF is also used as the collecting antenna.

33. A non-invasive method of detecting an abnormality in the tissue of a living organism, according to claim 31, in which the volume of the tissue that is illuminated by the antenna array in step FF is controlled by controlling a time delay of the applied signal to each antenna within the array.

34. A non-invasive method of detecting an abnormality in the living tissue of a living organism, according to claim 31, in which the scattered waves of volume of the tissue that is collected by the antenna array in step GG is controlled by controlling a time delay of the applied signal to each antenna within the array.

35. A non-invasive method of detecting a presence of a tumor or other abnormality in the tissue of a living organism, such as a tumor on the prostate gland, wherein normal tissue has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality or other tissue, and wherein surface tissue near the gland, such as the lining of the rectum, has a different dielectric characteristic than the normal tissue, the method comprising:

LL. generating a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

MM. applying the input wave of step LL to a cylindrical antenna that is positioned on surface tissue of the urethra such that it preferentially is in contact with the skin of a living organism to illuminate a preselected volume within the tissue of the living organism and develops scattered waves from that volume;

NN. collecting scattered waves from the preselected portion of the living tissue by a collecting antenna that is positioned on the surface tissue of the living organism such that it preferentially collects the scattered waves from the preselected volume of step MM to develop a series of secondary scattered waves that includes surface tissue scattered waves;

OO. processing each of the secondary scattered waves of step NN to separate surface tissue scatter and scatter from equipment interfaces from the secondary scattered waves and to develop a segregated scattered wave;

PP. repeating steps MM, NN, and OO to develop another segregated scattered wave from another preselected volume; and

QQ. combining the segregated scattered waves of steps NN and PP in a display that shows the position of abnormalities in the tissue.

36. A non-invasive method of detecting an abnormality in the tissue of a living organism, according to claim 35, in which the radiating antenna of step MM is also used as the collecting antenna of step NN.

37. A non-invasive method of detecting an abnormality in the tissue of a living organism, according to claim 35, in which the volume of the tissue that is illuminated by the antenna of step MM is controlled by repositioning the antenna of step MM.

38. A non-invasive system for detecting presence of a tumor or other abnormality in the tissue of a living organism, such as the tissue of a human breast, wherein normal tissue of the organism has a predetermined dielectric characteristic different from the dielectric characteristic of a tumor or other abnormality, and wherein surface tissue such as skin has a different dielectric characteristic than the normal tissue, the system comprising:

a signal generator to generate a non-ionizing electromagnetic input wave within a preselected wide band frequency range;

at least one radiating antenna, connected to the signal generator and aligned with the skin of a living organism, directing at least a portion of the input power into a discrete volume within the tissue of the living organism to illuminate the discrete volume and develop at least one scatter waves reflected from the discrete volume;

at least one collector antenna for collecting at least a portion of the at least one scatter wave from the discrete volume in the living organism;

a signal processor, connected to the at least one collector antennae;

a separator circuit to separate the at least one scatter wave from the preselected volume from the input wave and from other scatter waves from spurious scatter sources; and

storage means, connected to the separator, for storing the at least one scatter wave from the preselected discrete volume.

39. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which the radiating antennae each include two spaced electromagnetically excited conductive surfaces.

40. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which:

each radiating antenna includes two spaced conductive surfaces which are generally triangular in shape;

the input wave is applied to each conductive surface of each radiating antenna in phase opposition; and

the system further comprises a balun to convert an unbalanced input wave to a balanced, oppositely phased input wave.

41. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 40, in which the electrical parameters of materials used for each radiating antenna are spatially distributed to suppress unwanted reflections.

42. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which the radiating antennae are encapsulated in a radiating antenna array, the encapsulating material of the radiating antennae having a dielectric characteristic between the dielectric characteristics of normal breast tissue and surface tissue.

43. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 42, in which the relative dielectric constant of the encapsulating material is in a range of 4 to 40.

44. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 42, and further comprising:

positioning means for positioning the radiating antennae at a given known location in direct contact with the skin of a human breast.

45. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 44, in which the positioning means includes encapsulating material, similar to the material which encapsulates the radiating antennae, having a dielectric characteristic that is between the dielectric characteristics of normal breast tissue and of the skin tissue.

46. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 45, in which the relative dielectric constant of the encapsulating material is in a range of 4 to 40.

47. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which the system further comprises time averaging means for averaging the amplitude of collected scatter waves over a predetermined time period to enhance the signal-to-noise ratio of the collected scatter waves.

48. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which at least one radiating antenna forms a tubular beam to illuminate the discrete volume.

49. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 48, in which:

at least one radiating antenna and at least one collector antenna are the same.

50. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 38, in which the system further comprises:

at least one switching circuit, interposed between the signal generator and the radiating antennae, to modify the input wave so that it is directed into a second discrete volume within the tissue of the living organism.

51. A non-invasive system for detecting the presence of a tumor or other abnormality in the tissue of a living organism, according to claim 50, in which the system further comprises:

at least one switch interposed between each collector antenna and the signal processor.