Apparatus and method for near-field imaging of tissue

• US 20040254457A1
• Filed: 05/27/2004
• Published: 12/16/2004
• Est. Priority Date: 06/02/2003
• Status: Active Grant

• Current Assignee: Daniel W. Van Der Weide
• Original Assignee: Daniel W. Van Der Weide
• Inventors: van der Weide, Daniel Warren
• Granted Patent: US 7,725,151 B2
• Time in Patent Office: Days
• US Class Current: 600/430
• CPC Class Codes: A61B 5/0062 Arrangements for scanning
• 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 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure

Abstract

Using pulsed or continuous-wave sources, broadband electromagnetic energy generally in the 10 MHz to 300 GHz range is applied through one or a plurality of near-field antennas such as coaxial probe tips. The electromagnetic energy reflected from the surface or transmitted through the near surface of the object (e.g. surface of skin or other tissue or cells) is detected, and the ratio of the test measurement to that from normal tissue is recorded and presented to determine the degree of dielectric contrast, hence inhomogeneity. This degree of contrast is used both on its own and in conjunction with simultaneously acquired optical images to map the boundary of an organ inhomogeneity such as a tumor. The bundle of antennas may be scanned over a surface of the object on a pixel-by-pixel basis to determine the spectra of the sample on a pixel-by-pixel basis, allowing a two dimensional display of the absorption spectra to be provided.

Claims

1. A method for detection of dielectric anomalies at or near the surface of human or animal organs, including the skin, other tissues and cells, comprising:

(a) applying electromagnetic energy through one or a plurality of near-field antennas or probes using electrical pulses or continuous-wave excitation with one or a multiplicity of frequencies having content in the range of 10 MHz to 300 GHz;

(b) acquiring the reflection or transmission coefficient spectra or both from the object;

(c) assigning to the spectra or a portion thereof different colors to represent different values of the spectra, resulting in an image-like presentation that indicates dielectric contrast.

2. The method of claim 1 wherein the electromagnetic radiation is applied in pulses with a frequency synthesizer.

3. The method of claim 1 wherein applying electromagnetic radiation in pulses is carried out utilizing a pulse generator.

4. The method of claim 1 wherein the excitation is provided with drive signals from two sources, one of which provides a signal at a basis frequency fo and the other at a frequency of f₀-f_if where f_if is much less than f₀.

5. The method of claim 1 wherein acquiring the reflection or transmission spectra or both from the sample is carried out utilizing a diode detector.

6. The method of claim 1 wherein acquiring the reflection or transmission spectra or both from the sample is carried out utilizing a bolometric detector.

7. The method of claim 1 wherein acquiring the reflection or transmission spectra or both from the sample is carried out utilizing a diode sampler as the detector.

8. The method of claim 1 wherein acquiring the reflection or transmission spectra or both from the sample is carried out utilizing a frequency mixer as the detector.

9. The method of claim 1 wherein steps (a) and (b) are repeated on a pixel-by-pixel basis over the surface of an object.