A noninvasive accurate method for measuring the temperature of tissue beneath the surface of a living body is described. Ultrasonic signals are directed into beads of a material that are inserted into the tissue with a syringe. The reflected signals indicate the acoustic impedance or resonance frequency of the beads 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

Brandenburger, G. H.

Heyman, J. S.

English

NASA Technical Reports Server

United States Patent [191 
Heyman et al. 
[54] METHOD FOR THERMAL MONITORING 
[75] Inventors: Joseph S. Heyman, Williamsburg, 
Va.: Gary H. Brandenburger, 
Bellevue, Wash. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
SUBCUTANEOUS TISSUE 
[73] Assignee: The United States of America as 
[21] Appl. NO.: 582,492 
[22] Filed: Feb. 22, 1984 
[51] 
[52] 
[58] 
[561 References Cited 
Int. C1.: .............................................. A61B 10/00 
U.S. C1. .................................... 128/660; 128/736; 
374/117; 374/160 
Field of Search ............. 128/660, 661, 804, 24 A, 
128/736; 374/1 17, 160  
U.S. PATENT DOCUMENTS 
3.577.981 5/1971 Kuris ................................... 128/663 
3.609.731 9/1971 Evans .............................. 374/117 X 
3.893.1 1 1  7/1975 Cotter ............................. 128/736 X 
4.105.018 8/1978 Greenleaf et al. .................. 128/660 
[ I  I ]  Patent Number: 4,513,750 
[45] Date of Patent: Apr. 30, 1985 
4,138.998 21'1979 Nowogrodzki ................. 128/736 X 
4.246.784 1/1981 Bowen ................................ 128/736 
4.315,514 2/1982 Drewes et al. ................. 128/660 X 
4.323,077 4/1982 Smith .................................. 128/660 
4.340.796 7/1982 Yarnaguchi et a]. ........... 374/1 17 X 
4.373.532 2/1983 Hill et al. ............................ 128/660 
4.390.026 6/1983 Christman ........................... 128/660 
4.452,081 6/1984 Seppi ............................... 128/660 X 
Prirnory Exominer-Kyle L. Howell 
Assistonr Examiner-Francis J. Jaworski 
Arrorney, Agent, or Firm-William H. King; John R. 
Manning; Howard J. Osborn 
[571 A B S T R A a  
A noninvasive accurate method for measuring the tem- 
perature 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 impe- 
dance 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. 
8 Claims, 4 Drawing Figures 
IMPEDANCE 
MEASU R I N G 
DEVICE 
https://ntrs.nasa.gov/search.jsp?R=19850022306 2020-03-22T19:33:58+00:00Z
U.S. Patent Apr. 30,1985 Sheet 1 of2 4,s 13,750 
I 
FIG. 1 
R E S O N A N T  
F R E O U E N C Y  
15 
23 
FIG. 2 
I 
Y 
FIG. 4 
U.S. Patent Apr. 30,1985 Sheet 2 of 2 4,s 13,750 
c. - .C 
4.513.750 
1 
METHOD FOR THERMAL MONITORING 
SUBCUTANEOUS TISSUE 
ORIGIN OF T H E  INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 85-568 
(72 Stat. 435; 42 USC 2457). 
BACKGROUND O F  THE INVENTION 
The invention relates generally to the treatment of 
cancer by localized heating of the tumor cells using 
microwave radiation or other heating means and more 
specifically concerns accurately monitoring the temper- 
ature of subcutaneous tissue in the region of the tumor. 
Nonsurgical elimination of malignant tumors has 
been approached using various techniques. Only limited 
success has been realized using chemotherapy and/or 
x-ray irradiation, and both techniques frequently elicit 
distressing side effects. In contrast, nonionizing micro- 
wave or ultrasonic energy are potential alternatives, 
whose side effects may be less severe than those of 
ionizing radiation such as x-ray. Unlike chemotherapy 
which acts systematically, the side effects of microwave 
and ultrasound, if any, are localized. Microwave (1-10 
GHz electromagnetic energy) and ultrasound waves 
(generally of Megahertz frequency) can be generated 
inexpensively without the cost, bulk, or hazards of the 
radiation and high voltage supplies required for x-ray. 
Unlike x-ray irradiation, microwave and ultrasound 
destroy malignant cells strictly by localized heating of 
the affected region. Advantage is taken on the malig- 
nant cell's higher sensitivity to temperature relative to 
that of normal tissue. In addition, reduced destruction 
of healthy tissue is achieved by concentrating several 
different energy sources on the tumor region, as is done 
with x-ray. Significant malignant cell destruction oc- 
curs for temperatures above a threshold of 43" C. Below 
this threshold, however, malignant cell growth may be 
accelerated. Thus, careful control of temperature must 
be maintained in the vicinity of the tumor: Too much 
energy may destroy surrounding healthy tissue; too 
little might aggravate tumor enlargement. 
Noninvasive localized temperature sensing methods 
such as infrared detection of skin surface temperature 
and microwave thermometry have proved to  be unreli- 
able indicators of the temperature in underlying tissue 
such as the breast. Surgically implanted, invasive tem- 
perature probes are at risk of causing tumor metastasis; 
this constitutes a significant hazard, particularly for 
breast tumors which frequently are the site of the pri- 
mary malignancy. Furthermore, such probes are an 
infection risk and cannot be used during irradiation 
without resulting in localized heating. Thus, a noninva- 
sive but accurate method for measuring the temperature 
of underlying tissue is required if microwave or ultra- 
sonic irradiation is to become a viable form of cancer 
treatment. 
It is therefore an object of this invention to  provide a 
noninvasive but accurate technique for measuring the 
temperature of underlying tissue. 
Another object of this invention is to provide a tech- 
nique based on ultrasound for measuring tissue tempera- 
ture. 
2 
A further object of this invention is to provide a 
technique for measuring tissue temperature suitable for 
use with microwave or ultrasound treatment of cancer. 
Still another object of the invention is to provide a 
5 technique for measuring tissue temperature which is 
safe enough to permit frequent, repeated measurements 
without accumulated exposure hazard to  either the 
patient or the medical staff. 
A still further object of the invention is to provide a 
10 noninvasive technique for measuring tissue temperature 
which is accurate to within 0.5" C. over the range of 35" 
c .  to 45" c .  
Yet another object of this invention is to  provide a 
noninvasive technique for measuring tissue temperature 
15 which is accurate over a wide range of temperatures. 
Other objects and advantages of this invention will 
become apparent hereinafter in the specification and 
drawings. 
SUMMARY OF THE INVENTION 
The invention is a noninvasive accurate method for 
measuring the temperature of tissue beneath the surface 
of a medium such as in a living body. Beads of a material 
having a predetermined melting temperature are in- 
25 serted into the tissue by means of a syringe. Then ultra- 
sonic signals are focused on the beads and the acoustic 
impedance of the beads is determined from the reflected 
signals. The acoustic impedance of the beads is indica- 
tive of the state (solid, liquid ) of the beads which is 
30 indicative of the temperature of the tissue. Conse- 
quently, this invention can be used to measure a small 
range of temperatures around the melting temperature 
of the bead material. 
BRIEF DESCRIPTION OF T H E  DRAWINGS 
FIG.  1 is a schematic drawing for describing the 
FIG. 2 is a schematic drawing for describing how the 
FIG. 3 is a schematic drawing for describing a varia- 
FIG. 4 is a schematic drawing for describing a second 
20 
35 
method of this invention; 
material used as the beads in FIG. 1 is calibrated; 
tion of and 
variation of the invention. 
40 
D E T A I L E D  DESCRIPTION OF THE - INVENTION 4 5  
The method of ultrasonic temperature measurement 
utilized by this invention is demonstrated in FIG.  1. A 
section 11 of a human body has a tumor 12 beneath the 
5 0  surface. In the treatment of the tumor with microwave 
or other radiation, the radiation is directed into the 
body by equipment (not shown) to  heat the tumor 12. 
The tumor must be heated above 43" C. to  have signifi- 
cant malignant cell destruction. As the radiation is di- 
55 rected into the tumor to  heat the tumor, the temperature 
of the tissue in the region surrounding the tumor will 
rise. It is necessary that the temperature in the region 
surrounding the tumor not substantially exceed 43" C.: 
healthy tissue will be destroyed if the temperature rise is 
60 too high. Consequently, the temperature surrounding 
the tumor must be monitored during the heating of the 
tumor to protect the healthy tissue. Also, the tempera- 
ture surrounding the tumor will be indicative of the 
temperature in the tumor. 
To monitor the temperature in the healthy tissue 
surrounding the tumor, several beads 13 of a material 
are inserted into the healthy tissue surrounding the 
tumor by means of a syringe. The material in beads 13 
65 
a variation of the method of this invention as nals at said beads in only one direction. 
shown in FIG. 3, a first transducer 30 directs a first 6. A method for monitoring temperatures according 
65 


Method for thermal monitoring subcutaneous tissue

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