Method for thermal monitoring subcutaneous tissue

• US 4,513,750 A
• Filed: 02/22/1984
• Issued: 04/30/1985
• Est. Priority Date: 02/22/1984
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Heyman, Joseph S., Brandenburger, Gary H.
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): Jaworski, Francis J.
• Application Number:
  US06/582,492
• Time in Patent Office: 433 Days
• Field of Search: 128/660, 128/661, 128/804, 128/24 A, 128/736, 374/117, 374/160
• US Class Current: 600/438
• CPC Class Codes: A61B 10/00 Other methods or instruments for diagnosis, e.g. instruments for taking a cell sample, for biopsy, for vaccination diagnosis vaccination prophylaxis, vaccination therapy A61B17/20; Sex determination; Ovulation-period determination menstruation tables G06C3/00; Throat striking implements
• CPC Class Codes: A61B 8/5223 for extracting a diagnostic or physiological parameter from medical diagnostic data for algorithms to analyse biomedical images G06T7/0012
• CPC Class Codes: A61N 7/02 Localised ultrasound hyperthermia hyperthermia in general A61F7/00
• CPC Class Codes: G01K 11/22 using measurement of acoustic effects
• CPC Class Codes: G01N 2291/02881 Temperature
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A noninvasive accurate method for measuring the temperature of tissue beneath the surface of a living body 11. Ultrasonic signals (14) are directed into beads 13 of a material that are inserted into the tissue with a syringe. The reflected signals (15) indicate the acoustic impedance or resonance frequency of the beads 13 which in turn indicates the temperature of the tissue. A range of temperatures around the melting temperature of the material can be measured by this method.

Claims

1. A method for monitoring temperatures about a selected temperature in any medium especially in subcutaneous tissue in a living body comprising the steps of:

inserting beads of a material having a melting point approximately equal to said selected temperature, into said medium;

directing ultrasonic signals at said beads; and

receiving the ultrasonic signals reflected by said beads whereby the received signals contain information representative of the acoustic impedance of said beads which is indicative of the temperature in said medium.

2. A method for monitoring temperatures according to claim 1 including the step of measuring the acoustic impedance of said beads from said received signals.

3. A method for monitoring temperatures according to claim 1 wherein said beads are inserted into subcutaneous healthy tissue in the vicinity of a tumor whereby the temperature of the tumor can be monitored.

4. A method for monitoring temperatures according to claim 1 including the step of calibrating the change in acoustic impedance with temperature of said material.

5. A method for monitoring temperatures according to claim 1 wherein said step of directing ultrasonic signals at said beads comprises directing ultrasonic signals at said beads in only one direction.

6. A method for monitoring temperatures according to claim 1 wherein said step of directing ultrasonic signals at said beads comprises directing ultrasonic signals at a first frequency at said beads in a first direction and directing ultrasonic signals at a second frequency at said beads in a second direction and receiving the mixed scattered signal at the sum and/or difference frequency to measure the temperature at the mixing volume.

7. A method for monitoring temperatures in subcutaneous tissue comprising the steps of:

inserting a bead of material, that changes resonant frequency with temperature, into said subcutaneous tissue;

directing ultrasonic signals at said bead of material; and

receiving the ultrasonic signals reflected by said bead whereby the received signal contains information representative of the resonant frequency of said bead of material which is indicative of the temperature in said subcutaneous tissue.

8. A method for monitoring temperatures according to claim 7 including the step of measuring the resonant frequency of said bead from said received signal.