Surgery – Truss – Pad
Patent
1992-09-21
1994-08-30
Kamm, William E.
Surgery
Truss
Pad
G01J 510, A61B 1000
Patent
active
053418140
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the determination of the temperature of a given material or object, as well as of its microwave frequency reflection coefficient.
To determine the temperature of an object, it is known in the art to use measuring processes whereby the thermal noise signals emitted by this object in the microwave frequency range are picked up and a correspondence is established between strength of the signals picked up and the temperature of the object.
In this connection, the term "object" is to be taken in a very broad sense as it can refer equally well to a material object or to a material, or even to living tissues. Any absorbent body in fact emits thermal noise signals directly related to its temperature. Such thermal noise signals are emitted over a very wide frequency range.
2. Description of Background Information
To carry out temperature measurements, there are also known other processes using signals emitted in the infrared range. However, the drawback is that the signal picked up are emitted primarily by the surface of the body to be measured and the surface temperature cannot then be measured.
Another known measuring method consists in using a thermocouple, which is necessarily introduced inside the body the temperature of which one wishes to measure. However, in very many cases, the penetration of the body by the thermocouple represents a major drawback.
To avoid such drawbacks, it is preferred to make use of the thermal noise signals emitted in the microwave frequency range, that is to say frequencies ranging approximately between 0.5 and 20 GHz.
In this connection, there are known microwave radiometry devices in which the microwave radiation emitted via an antenna is picked up and the signals received are routed to signal processing means which enable the temperature of the object in question to be determined.
However, on of the main problems encountered in microwave frequency radiometry resides in the matching of the antenna in respect of the material the temperature of which one wishes to know. Indeed, the antenna used has a reflection coefficient R.sub.o and, as a result, the antenna is never perfectly matched, given that the objects to be measured generally have different configurations, sizes and properties.
Under these circumstances, the error made in measuring the temperature of the object, due to the fact that the coefficient .vertline.R.sub.o .vertline..sup.2 of the antenna is different from zero, has two implications, namely: on one hand, the emissivity of the object: =1-.vertline.R.sub.o .vertline..sup.2 is different from unity and, on the other hand, given the reflection coefficient of the antenna, a part of the noise emitted at the input of the signal processing means is reflected by the antenna, and then amplified by the said means, and thus unduly contributes to the signal measured at the output of the said means.
To remedy these different drawbacks, different processes have been devised to enable the internal temperature of a body to be measured without thereby necessitating the introduction into this body of means to detect this temperature.
Document FR-2,497,947, in fact, discloses a microwave thermography device and process based on the principle of the Dicke radiometer, using an antenna, a circulator, an auxiliary source of noise with known characteristics, an amplifier-receiver and a detector. In addition, according to this document, the use of a circulator is associated with a two-channel microwave frequency switch cyclically connecting the measuring line to the antenna or short circuiting the measuring line.
Thus, this circulator-switch assembly, on one hand, enables the signal emitted at the input of the amplifier to be absorbed and, on the other hand, enables the antenna to be presented with a temperature load substantially equal to that of the material to be measured. Under these conditions, when the coefficient .vertline.R.sub.o .vertline..sup.2 is different from zero, the reduction in noise emitted by t
REFERENCES:
patent: 4346716 (1982-08-01), Carr
patent: 4491976 (1985-01-01), Saitoh et al.
patent: 4627442 (1986-12-01), Land
patent: 4677988 (1987-07-01), Constant et al.
patent: 5220927 (1993-06-01), Astrahan et al.
D. Vanloot et al., L'onde Electrique, "New Low Frequency Electronic Circuit for Signal Processing Designed for Medical Radiometers", vol. 69, No. 5, Sep./Oct. 1989, pp. 60-65.
I. M. Angelov et al., Conference Proceedings, 19th European Microwave Conference, "Radiometer for Microwave Thermography", London, 4-7 Sep. 1989, Microwave Exhibitions an Publishers Ltd., pp. 924-929.
Y. Kato et al., IEEE Transactions on Microwave Theory and Techniques, "A Method for Evaluating the Noise Sources by Introducing an Auxillary Transmission Line", vol. 36, No. 1, Jan. 1988, pp. 145-147.
English and French copies of the International Search Report and Annex.
Constant Eugene
Van De Velde Jean-Claude
Centre National de la Recherche Scientifique
Kamm William E.
Manuel George
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