Microwave antenna for cancer detection system

• US 6,061,589 A
• Filed: 09/09/1997
• Issued: 05/09/2000
• Est. Priority Date: 07/01/1994
• Status: Expired due to Term

• Current Assignee: Interstitial, LLC
• Original Assignee: Interstitial, Inc.
• Inventors: Hagness, Susan C., Taflov, Allen, Sahakian, Alan, Bridges, Jack E.
• Primary Examiner(s): Casler, Brian L.
• Application Number:
  US08/926,621
• Time in Patent Office: 973 Days
• Field of Search: 324/637, 324/638, 324/639, 324/642, 343/700 R, 342/361, 600/430, 607/101, 607/156
• 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

Abstract

A microwave antenna for use in a system for detecting an incipient tumor in living tissue such as that of a human breast in accordance with differences in relative dielectric characteristics. In the system a generator produces a non-ionizing electromagnetic input wave of preselected frequency, usually exceeding three gigahertz, and that input wave is used to irradiate a discrete volume in the living tissue with a non-ionizing electromagnetic wave. The illumination location is shifted in a predetermined scanning pattern. Scattered signal returns from the living tissue are collected and processed to segregate skin tissue scatter and to develop a segregated backscatter or return wave signal; that segregated signal, in turn, is employed to detect any anomaly indicative of the presence of a tumor or other abnormality in the scanned living tissue. The present invention is directed to a composite Maltese Cross or bow-tie antenna construction employed to irradiate the living tissue and to collect backscatter or other scatter returns.

Claims

1. A very wide band transmission/reception antenna for a non-ionizing, non-thermal system for detecting the presence of a tumor or an abnormality in the tissue of a living organism, said antenna comprising:

a first radiation element of generally triangular planar configuration having an apex constituting one corner thereof,

a first receiver element of generally triangular planar configuration having an apex constituting one corner thereof,

said corners of said first radiation element and said corner of said first receiver element being located closely adjacent each other,

a wide band width transmitter connected to said corner of said first radiation element,

a wide band width receiver connected to said corner of said first receiver element,

said first radiation element and said first receiver element each formed of an electrically conductive surface on a planar surface of a dielectric member,

said dielectric member having a relative dielectric characteristic approximately the same as the dielectric characteristic of the living organism tissue,

each electrically conductive surface decreasing in conductivity in a direction away from its said apex.

2. The very wide band transmission/reception antenna of claim 1, further comprising:

a second radiation element of generally triangular planar configuration having an apex constituting one corner thereof,

a second receiver element of generally triangular planar configuration having an apex constituting one corner thereof,

all of said apex corners of said radiation and receiving elements being located closely adjacent to one another,

said wide band width transmitter connected to said first and second radiation element, and

said wide band width receiver connected to said first and second receiver elements.

3. The very wide band transmission/reception antenna of claim 1, wherein said radiation element and said receiver element each have a fixed polarization with respect to each other of 90°

to suppress interaction between them.

4. The very wide band transmission/reception antenna of claim 1, wherein the conductivity of each electrically conductive surface is varied by progressively removing said conductive material in a direction away from its said apex.

5. A very wide band transmitter/receptor antenna for a non-ionizing, non-invasive, non-thermal system to detect the presence of a tumor or abnormality in the tissue of a living organism comprising:

a signal generator providing an electromagnetic input wave over a very wide bandwidth having two output points;

a very wide band receiver having two input points;

at least one transmitting antenna, directing at least a portion of the input power into the tissue of living organism into a discrete volume and developing at least one scatter wave from said discrete volume;

a transmitting antenna with two conductive surfaces having two connection points connected to said two output points of the signal generator;

at least one receptor antenna for collecting at least a portion of a scatter wave from said discrete volume of said living organism having two output points;

said receptor antenna with two conductive surfaces having two connection points connected to said two input points of said receiver;

said conducting surfaces of said transmitting antenna and of said receptor antenna formed on a surface of a dielectric member having a dielectric characteristic similar to the dielectric characteristic of said living organism;

each of said electrically conducting surface decreasing in conductivity in a direction away from its said connection point.

6. The antenna of claim 5, in which said conducting surfaces are triangular and have one of said connection point near each corner of each of said triangular surfaces.

7. A very wide bandwidth transmission/receptor antenna for a non-ionizing, non-thermal system for detecting the presence of a tumor or an abnormality in the tissue of a living organism, according to claim 6 where the resistive loading taper in ohms per square is used, according to the formula:

R(z)={R_o [1+(R_1/2 /R₀ -2)(z/h)]}[1-z/h ]^-1, z/h is the normalized distance along the bow-tie for the apex to the distal end, and where the approximate values of each parameter in the formula are within a factor of 3 of the approximate values of each parameter in the formula are within a factor of 3 of the following values;

R_o =3.5×

10^-5, and R_1/2 =110 and R_1/2 is the surface resistance when z/h-0.5;

where the values of R_1/2 can further range between 10 to 200 ohms per square.

8. The antenna of claim 5, in which said transmitting antenna and said receptor antenna are the same.

9. The antenna of claim 5, in which the radiating portion of said transmitting antenna and the receiving portion of said other of the receptor antennas have a fixed polarization with respect to each other of 90 degrees to suppress interaction between them.

10. The antenna of claim 9, in which said transmitting and receptor antennas are co-located.

11. The antenna of claim 5, wherein the conductivity of each electrically conductive surface is varied by progressively removing conductive material in a direction away from the connection points.

12. The antenna of claim 5, wherein said conductive surface of each of said transmitting and reception antennas are of planar configuration.

13. A very wide band transmitter/receptor antenna for a non-ionizing, non-invasive, non-thermal system to detect the presence of a tumor or abnormality in the tissue of a living organism comprising:

a signal generator generating an electromagnetic input wave over a very wide bandwidth having two output points,

a very wide band receiver having two input points,

at least one transmitting antenna, directing at least a portion of said input power into said tissue of said living organism an developing at least one scatter wave from said living organism,

said transmitting antenna with two conductive surfaces having two connection points connected to said two output points of the signal generator,

at least one receptor antenna for collecting at least a portion of said scatter wave from said living organism having two output points,

said receptor antenna with two conductive surfaces having two connection points connected to said two input points to said receiver,

said conducting surfaces of said transmitting antenna and of said receptor antenna are formed on the surface of a dielectric medium having a dielectric characteristic similar to the dielectric characteristic of said living organism,

each said electrically conducting surface decreasing in conductivity in a direction away from its said connection point.