Indicating temperature within living tissue

• US 4,138,998 A
• Filed: 08/18/1976
• Issued: 02/13/1979
• Est. Priority Date: 08/18/1976
• Status: Expired due to Term

• Current Assignee: RCA Corporation
• Original Assignee: RCA Corporation
• Inventors: Nowogrodzki, Markus
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Jaworski, Francis J.
• Application Number:
  US05/715,220
• Time in Patent Office: 909 Days
• Field of Search: 128/20, 128/404, 128/413, 128/422, 128/303.17, 128/2 H, 340/228 R, 340/228 F, 219/10.55 R, 219/10.55 M, 219/10.55 E, 236/88
• US Class Current: 600/430
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61N 5/02 using microwaves
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 7/36 using magnetic elements, e.g. magnets, coils magnetic elements per se H01F

Abstract

A reflector that reflects a microwave signal as a function of temperature is implanted within living tissue of a human. A microwave signal is transmitted to the reflector via an applicator in contact with the skin of the human. A portion of the signal reflected from the reflector is coupled via the applicator to a meter that provides an indication of the temperature of the reflector.

Claims

1. Apparatus for indicating temperature within living tissue, comprising:

impedance varying reflector means responsive to temperature changes for changing its impedance as a function of temperature;

said reflector means adapted for implantation within said tissue for positioning to reflect impinging microwave signals;

a microwave signal transmitter providing said microwave signal to said reflector at a predetermined frequency;

a meter for indicating the level of a reflected microwave signal reflected from said reflector in response to said microwave signal from said transmitter;

applicator means, adapted for contact with said tissue, for providing a substantially matched impedance at a given temperature for coupling microwave signals to and from said tissue; and

means for coupling said transmitted microwave signal from said transmitter to said applicator means for application to said tissue and said reflector and for coupling to said meter a microwave signal reflected to said applicator means from said reflector;

whereby said reflector in response to changes in temperature of said tissue from said given temperature will cause the level of said reflected signal to change as a function of said temperature changes in said tissue.

2. Apparatus according to claim 1 wherein said reflector means includes a ferrite material that has a Curie temperature in a range of 43°

C. to 55°

C.

3. Apparatus according to claim 12 wherein said ferrite material is comprised of a lithium-aluminum ferrite.

4. In the method of providing an indication of temperature within living tissue, the steps of:

transmitting a microwave signal at a predetermined frequency into said tissue;

reflecting a microwave signal from an impedance varying reflector positioned within said tissue, said reflected signal from said reflector having a signal level that is a function of said temperature; and

indicating said reflected signal level as a representation of temperature within said tissue.