Apparatus and method for image reproduction of materials using their magnetic and electric properties

• US 4,493,039 A
• Filed: 05/06/1980
• Issued: 01/08/1985
• Est. Priority Date: 05/06/1980
• Status: Expired due to Term

• Current Assignee: President and Directors of Georgetown University
• Original Assignee: President and Directors of Georgetown University
• Inventors: Gregory, William D.
• Primary Examiner(s): Krass, Errol A.
• Assistant Examiner(s): Chin, Gary
• Application Number:
  US06/147,297
• Time in Patent Office: 1,708 Days
• Field of Search: 364/413-415, 364/516-517, 324/61 R, 324/200, 324/228, 324/232, 324/233, 324/262, 324/239, 128/653
• US Class Current: 324/228
• CPC Class Codes: G01N 27/82 for investigating the presence of flaws
• CPC Class Codes: G01R 27/2617 Measuring dielectric properties, e.g. constants testing dielectric strength G01R31/12; detecting insulation faults G01R31/52; G01R27/2688 takes precedence
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12

Abstract

Pictorial images of selected volume elements of materials are generated by a contactless, non-destructive, substantially hazard free tomographic technique in which the material is brought within the influence of a relatively low-strength electromagnetic field and subjected to plural preselected frequencies to provide output data which is used to generate an image reflective of the magnetic and/or electric and/or conductance properties of the selected volume elements. This data has a high volume information content which enables accurate and reproducible identification of the material under investigation. The technique has application in the medical diagnostic field such as for example in aiding in the detection of small areas of cancerous tissue present in a larger mass of healthy tissue.

Claims

1. Apparatus for generating an image of a material using at least one of its magnetic, electric permeability and conductance properties under substantially hazard-free field conditions and without establishing physical contact with the material, said apparatus comprising:

(a) electromagnetic field generating means for generating a relatively low-strength substantially hazard-free electromagnetic field and for producing an output signal when the material to be investigated is brought within the influence of said electromagnetic field and out of physical contact with said electromagnetic field generating means, said output signal having a value which is reflective of said at least one of the magnetic, electric permeability and conductance properties of at least one volume element of said material, said at least one volume element being defined by at least one of intersecting field lines of said electromagnetic field and intersecting planes of said material;

(b) frequency generating means connected to said electromagnetic field generating means for producing a frequency signal comprising a plurality of pre-selected frequencies, said frequency signal being applied to said electromagnetic field generating means for generating said electromagnetic field;

(c) output signal resolving means connected to said electromagnetic field generating means for resolving said output signal into separate resolved component values including a resolved reactive component value and a resolved non-reactive component value to said at least one volume element of said material for each of said pre-selected frequencies; and

(d) image generating means connected to said output signal resolving means for generating a pictorial image of said material from at least one of said resolved component values for at least one volume element, said pictorial image being reflective of said at least one of the magnetic, electric permeability and conductance properties of said at least one volume element.

2. Apparatus according to claim 1 and further including moving means located in the vicinity of said electromagnetic field generating means for causing relative movement of said material and said electromagentic field, whereby said at least one volume element of said material is brought within the influence of said electromagnetic field.

3. Apparatus according to claim 2 wherein said moving means moves said material to be investigated while said electromagnetic field generating means is maintained stationary.

4. Apparatus according to claim 1, wherein said electromagnetic field generating means comprises a coil system to which a signal having a phase is applied, and wherein the output signal of the electromagnetic field generating means is referenced to within about one degree of the phase of the signal applied.

5. Apparatus for generating an image of a material using its dielectric constant and conductance properties under substantially hazard-free electric field conditions and without establishing physical contact with the material, said apparatus comprising:

(a) capacitive means for generating a relatively low-strength substantially hazard-free electric field and for producing an output signal when the material to be investigated is brought within the influence of said electric field, said capacitive means including at least one capacitive element, said material being positionable within the influence of said electric field while out of physical contact with said capacitive element, said output signal having a value which is reflective of the dielectric constant and conductance properties of at least one volume element of said material, said at least one volume element being defined by at least one of intersecting field lines of said electric field and intersecting planes of said material;

(b) frequency generating means for producing a frequency signal comprising a plurality of pre-selected frequencies, said frequency signal being applied to said capacitive means for generating said electric field;

(c) output signal resolving means connected to said capacitive means for resolving said output signal into separate resolved component values, including a resolved capacitive component value and a resolved conductive component value for said at least one volume element of said material for each of said pre-selected frequencies; and

(d) image generating means connected to said output signal resolving means for generating a pictorial image of said material from at least one of said resolved component values for said at least one cross-sectional volume element, said pictorial image being reflective of at least one of the dielectric constant and conductance properties of said at least one volume element of said material.

6. Apparatus according to claim 5 wherein said at least one capacitive element includes at least two spaced apart capacitive plates having multiplexing means for adjusting the relative directional orientation of said electric field between and in the vicinity of said plates.

7. Apparatus according to claim 6 wherein said multiplexing means includes a plurality of capacitive units surrounded by at least one guard ring.

8. Apparatus for generating an image of material using its magnetic and conductance properties under substantially hazard-free magnetic field conditions and without establishing physical contact with the material, said apparatus comprising:

(a) magnetic field generating means for generating a relatively low-strength substantially hazard-free magnetic field and for producing an output signal when a material to be investigated is brought within the influence of said magnetic field, said magnetic field generating means including at least one electrically stable coil system, said material being positionable within the influence of said magnetic field while out of physical contact with said coil system, said output signal having a value which is reflective of the magnetic and conductance properties of at least one volume element of said material, said at least one volume element being defined by at least one of intersecting magnetic field lines of said magnetic field and intersecting planes of said material;

(b) frequency generating means connected to said magnetic field generating means for producing a frequency signal comprising a plurality of pre-selected frequencies, said frequency signal being applied to said magnetic field generating means for generating said magnetic field;

(c) output signal resolving means connected to said magnetic field generating means for resolving said output signal into separate resolved component values including a resolved true resistive component value and a resolved conductive value for said at least one volume element of said material for each of said pre-selected frequencies; and

(d) image generating means connected to said output signal resolving means for generating a pictorial image of said material from at least one of said resolved component values for said at least one volume element, said pictorial image being reflective of the magnetic and conductive properties of said at least one volume element of said material.

9. Apparatus according to claim 8 wherein said at least one electrically stable coil system includes at least one coil which generates a magnetic field along the longitudinal axis of said coil.

10. Apparatus according to claim 8, wherein a signal having a phase is applied to said electrically stable coil system, and the output signal is referenced to within about one degree of the signal applied.

11. Apparatus for generating an image of a human or animal body or part thereof using the dielectric constant and conductance properties of the body under substantially hazard-free electric field conditions and without establishing physical contact with the body, said apparatus comprising:

(a) capacitive means for generating a relatively low-strength substantially hazard-free electric field and for producing an output signal when said human or animal body or part thereof to be investigated is brought within the influence of said electric field, said capacitive means including at least one capacitive element having at least two spaced apart capacitive plates, said body and said capacitive means being movable relative to each other to vary the influence of said electric field while out of physical contact with said at least two spaced apart capacitive plates, said output signal having a value which is reflective of the dielectric constants and conductance properties of at least one volume element of said body, said at least one volume element being defined by at least one of intersecting field lines of said electric field and intersecting planes of said body;

(b) frequency generating means for producing a frequency signal comprising a plurality of pre-selected frequencies, said frequency signal being applied to said capacitive means for generating said electric field;

(c) output signal resolving means connected to said capacitive means for resolving said output signal into separate resolved component values including a resolved capacitive component value and a resolved conductive component value for said at least one volume element of said body for each of said pre-selected frequencies; and

(d) image generating means connected to said output signal resolving means for generating a pictorial image of said body from at least one of said resolved component values for said at least one volume element, said pictorial image being reflective of the dielectric constant and conductance properties of said at least one volume element of said material.

12. Method for generating an image of a material using at least one of its magnetic, electric permeability and conductance properties under substantially hazard-free field conditions and without establishing physical contact with the material, said method comprising the steps of:

(a) generating a relatively low-strength substantially hazard-free electromagnetic field so as to produce an output signal when a material to be investigated is brought within the influence of said electromagnetic field, said output signal having a value which is reflective of said at least one of the magnetic, electric permeability and conductance properties of at least one volume element of said material, said at least one volume element being defined by at least one of field lines of said electromagnetic field and intersecting planes of said material;

(b) establishing a reference value of said output signal in the absence of said material within the influence of said electromagnetic field, said output signal being measured with respect to a plurality of frequencies applied to said electromagnetic field generating means, said frequencies being pre-selected so that said output signal has a value which is reflective of said at least one of said magnetic, electric permeability and conductance properties when said material is brought within the influence of said electromagnetic field;

(c) introducing material to be investigated into the influence of said electromagnetic field at said plural pre-selected frequencies to produce an output signal having a value which is reflective of said at least one of the magnetic, electric permeability and conductance properties of said at least one volume element of said material;

(d) resolving said output signal into separate resolved component values including a resolved reactive component value and a resolved non-reactive component value for said at least one volume element of said material for each of said pre-selected frequencies; and

(e) generating a pictorial image of said material from at least one of said resolved reactive and non-reactive component values for at least said at least one volume element, said pictorial image being reflective of said at least one of the magnetic, electric permeability and conductance properties of said at least one volume element of said material.

13. Method according to claim 12 and further including the step of correcting for irregularities in the electromagnetic field caused by the presence of the material within the influence of the electromagnetic field by iterating said resolved reactive and non-reactive component values for said at least one volume element at each of said pre-selected frequencies, to thereby enhance the pictorial image generated by said image generating means.

14. Method according to claim 12 wherein said material is moved relative to the influence of said electromagnetic field while out of physical contact with said electromagnetic field.

15. Method according to claim 12 wherein said material is maintained stationary and said electromagnetic field is moved relative to said material with said material being within the influence of said electromagnetic field.

16. Method according to claim 12, wherein said electromagnetic field is produced as a result of application of a signal having a phase, and the output signal is referenced to within about one degree of the phase of the signal applied.

17. Method for generating an image of a human or animal body or part thereof using its dielectric constant and conductance properties, under substantially hazard-free capacitive electric field conditions and without establishing any physical contact with the body, said method comprising the steps of:

(a) providing a capacitive means for generating a relatively low-strength substantially hazard-free electric field so as to produce an output signal when said human or animal body or part thereof is brought within the influence of said electric field, said capacitive means including at least one capacitive element having at least two spaced apart capacitive plates, said body and said capacitive means being movable relative to one another, said body being within the influence of said electric field and out of physical contact with said at least two spaced apart capacitive plates, said output signal having a value which is reflective of the dielectric constant and conductance properties of at least one volume element of said body, said at least one volume element being defined by at least one of intersecting field lines of said electric field and intersecting planes of said body;

(b) establishing a reference value of an output signal of said capacitive means in the absence of said body within the influence of said electric field, said output signal being measured with reference to a plurality of frequencies applied to said capacitive means, said frequencies being pre-selected so that said output signal has a value which is reflective of the dielectric constant and conductance properties when said at least one volume element of said body is brought within the influence of said electric field;

(c) introducing said human or animal body or part thereof to be investigated into the influence of said electric field at said plurality of pre-selected frequencies to produce an output signal having a value which is reflective of the dielectric constant and conductance properties of said at least one volume element of said body;

(d) resolving said output signal into separate resolved component values including a resolved capacitive component value and a resolved conductive component value for said at least one volume element of said body for each of said pre-selected frequencies; and

(e) generating a pictorial image of said body from at least one of said resolved capacitive and conductive component values for said at least one volume element, said pictorial image including regions of contrasting lighter and darker zones and being reflective of the dielectric constant and conductance properties of said at least one volume element of said body.