JPS61181923A - Non-contact type measurement of temperature or the like - Google Patents

Abstract

PURPOSE:To enable the measurement of temperature or pressure at the depth in vivo while facilitating the measurement, by utilizing an ultrasonic wave which is relatively less in the attenuation in vivo along with limited noise component level. CONSTITUTION:An electromagnetic wave is made to irradiate a probe through an transmitting antenna coil L2 connected to a variable frequency oscillator 1 with a frequency counter 2 and an ultrasonic wave oscillated by the probe is received with a microphone 3. A measuring system is so arranged that after an electrical signal thereof is amplified to a required level with a high frequency amplifier 4, the electrical signal with the frequency the same as that of the ultrasonic wave is extracted with a filter 5 and the level thereof is observed with a level meter 6. Here, the oscillation frequency of the variable frequency oscillator 1 is varied and the frequency is detected with a frequency counter 2 at the point where the reading of the level meter is the maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a non-contact method for measuring temperature, etc., and particularly to a method for measuring temperature within a living body.

(Prior Art) Hyperthermia therapy has been attracting attention for the treatment of cancer in recent years, but in this case, accurate temperature measurement technology for nine local areas, including cancer cells and surrounding normal cells, is essential.

Conventionally, in order to measure the temperature inside a living body, a probe with a piezoelectric vibrator, such as a crystal oscillator, whose resonant frequency changes depending on the temperature, connected to an antenna coil is surgically implanted into the desired part of the living body. Alternatively, while flowing this into the digestive organ, irradiating electromagnetic wave energy of a required frequency from outside the body and applying it to the piezoelectric vibrator via the antenna coil and observing the energy absorption phenomenon when it resonates, or A method has been proposed in which the resonance frequency of the piezoelectric vibrator is detected by receiving the reverberation of the piezoelectric vibrator immediately after the electromagnetic energy irradiation is stopped via the antenna coil, and the total temperature is measured. .

This method of using electromagnetic waves and using a piezoelectric oscillator such as a crystal oscillator as a temperature sensor is extremely effective in eliminating the need for cables between the in-vivo probe and the external device and in performing accurate temperature measurements. Configuring a temperature sensor with a passive circuit without power supply is extremely effective when implanted in a living body for a long period of time.

However, as mentioned above, in the method of using temperature control using a passive circuit and utilizing the electromagnetic wave absorption phenomenon or reverberation phenomenon, the electromagnetic wave level obtained from this is extremely weak, making it very difficult to measure.・
There was a drawback in that it was not possible to maintain a large separation distance between the coil and the pickup coil of the in vitro device.

Furthermore, in the method of deriving electromagnetic waves from the probe as described above, when the object to be measured is a living body, the electromagnetic waves undergo large attenuation before reaching outside the living body, so the energy that can be extracted outside the living body is extremely weak. Moreover, measurements were even more difficult under conditions filled with miscellaneous electromagnetic noise, including commercial power supply frequencies.

Such electromagnetic noise is extremely loud in high-frequency heating devices commonly used for hyperthermia therapy for cancer, etc., and the conventional temperature measurement method described above requires a great deal of effort to eliminate the noise in the future. was.

According to experiments, in the conventional method described above, the separation distance between the antenna coil of the in-vivo sensor and the big-up coil of the extracorporeal device is at most 5 cst9. Measurements cannot be made unless the piezoelectric vibrator and the antenna coil are placed close to the body surface, either by separating them by a required length or by extending them both with a cable. It was inconvenient.

It is also possible to measure pressure by a similar method, in which case the structure of the senna is only slightly modified.

(Object of the Invention) The present invention has been made in view of the problems of the temperature or pressure measuring method as described above, and it uses ultrasonic waves that have relatively little attenuation in the living body and have a low noise component level. It is an object of the present invention to provide a non-contact temperature measurement method that facilitates measurement and enables measurement of temperature or pressure deep within a living body.

(Summary of the Invention) To achieve the above-mentioned object, the present invention takes the following measures.

That is, a piezoelectric vibrator whose resonant frequency is temperature- or pressure-dependent is connected to an antenna coil, and an ultrasonic transducer whose resonant frequency is the same as that of the piezoelectric vibrator, so as to form a loop. is used as a sensor probe and is attached to the surface or inside of the object to be measured, and an electromagnetic wave near the resonant frequency of the piezoelectric vibrator is applied from the outside to the probe via the antenna coil, causing the piezoelectric vibrator to resonate. The temperature or pressure of the object to be measured is measured by causing the ultrasonic transducer to oscillate with a current flowing through the transducer and observing the ultrasonic waves emitted from the outside.

(Example) The present invention will be described in detail below based on illustrated examples.

The first factor is a circuit diagram showing one embodiment of a probe as a sensor used in the present invention.

In the figure, Ll is an antenna coil, to which a crystal oscillator X and an ultrasonic transducer SW are connected in series so that these coils form a closed loop.

As the ultrasonic transducer SW, a piezoelectric vibrator such as a barium titanate vibrator or a quartz crystal vibrator is used in a thickness longitudinal vibration mode, and its resonant frequency is different from that of the center crystal vibrator X. For example, the frequency is 13.56 MHz.

The antenna coil f is attached to the probe configured in this way.
When an electromagnetic wave near the resonant frequency of the crystal oscillator The transducer is activated and generates ultrasound at the same resonant frequency.

Therefore, by extracting the ultrasonic wave from the outside and measuring its frequency, the resonant frequency of the crystal oscillator can be determined.If the relationship between the resonant frequency and temperature or pressure is known in advance, these values at that time can be determined. can be measured.

However, it is desirable that the resonant frequencies of the crystal oscillator X and the ultrasonic transducer SW are always the same at all temperatures or pressures.

The Q value of this ultrasonic transducer is in a considerably reduced state, so even if this is slightly different, an ultrasonic vibration output corresponding to the resonant frequency of the crystal can be obtained, albeit with a slight decrease in efficiency. There is no difference.

Although various structures can be considered for this ultrasonic transducer, for example, it may be constructed as shown in FIG.

That is, the electrodes 8, 8t- are placed at both ends in the vibration direction of the vibrator 7, which is made of barium titanate having a resonance frequency that is equal to that of the crystal vibrator in the thickness longitudinal vibration mode.
The ultrasonic transducer, the crystal oscillator Ll
and the electrodes 8, 8 are connected in series.

In addition, as a method of detecting the frequency of the crystal resonator described above, instead of measuring the ultrasonic frequency of the ultrasonic transducer and the user SW, the frequency of the electromagnetic wave irradiated from the outside is changed, and the ultrasonic wave output is maximized. This may be done by observing electromagnetic wave frequencies.

That is, FIG. 2 shows a block diagram of an embodiment of an external measuring device used when carrying out such a measuring method.

In the same figure, reference numeral 1 denotes a variable frequency oscillator with a frequency collar 2, which irradiates the globe with electromagnetic waves through a transmitting antenna coil L2t connected to it, and the oscillator oscillated by the probe. A measurement system is provided in which a sound wave is received by a microphone 3, the electric signal thereof is amplified to a required level in a high frequency amplifier 4, an electric signal having the same frequency as the ultrasonic wave is extracted by a filter 5, and its level is observed by a level meter 6. At the same time, the oscillation frequency t of the variable frequency oscillator 1 is changed and the frequency at which the reading of the level meter becomes maximum is detected by the frequency counter 2.

At this time, if a means is added to detect the point at which the reading of the level meter 6 is maximum, and the oscillation local wave number of the variable frequency oscillator 1 is controlled by the output of the means, the ultrasonic output can be maximized. It is extremely convenient because it can automatically measure the electromagnetic wave frequency.

Although the present invention has been described in detail based on one embodiment, it is not necessary to limit the present invention to this.

For example, in the probe, the electromagnetic waves irradiated from the outside are once converted into direct current, and this is used as a power source for a newly configured ultrasonic oscillation circuit, and the transducer of the ultrasonic frequency has temperature or pressure dependence. The ultrasonic frequency may be measured externally using a .

Furthermore, although the above explanation focuses on the temperature measurement method, it is well known that the resonant frequency of the piezoelectric vibrator has dependence on pressure as well, so pressure can be measured using a method similar to the above explanation. It is clear that it is possible.

(Effects of the Invention) As explained above, the present invention is designed to convert electromagnetic waves irradiated from the outside into ultrasonic waves with excellent propagation characteristics in the whole body, and to measure temperature or pressure by observing the ultrasonic waves. Therefore, it is very effective in eliminating the influence of various electromagnetic wave noises and providing an efficient non-contact temperature or pressure measuring method.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the probe used in the present invention, Fig. 2 is a block diagram showing an embodiment of the in vitro measuring device used in the present invention, and Figs. FIG. 2 is a diagram showing an example of the structure of an ultrasonic transducer used in the probe of the invention. l......Variable frequency oscillator, 2...
・・・・・・Frequency counter, 3・・・−・−・・
・Ultrasonic microphone, 4・・・・−・・High frequency amplifier. 5...-...Filter, 6...
...Level meter, 7 and 9...
Barium titanate oscillator, 8,8...
・Electrode, Ll and L2...Antenna coil, X...Crystal oscillator,
SW・・・・・・Ultrasonic transducer. Patent applicant Toyo Tsushinki Co., Ltd. Figure 1 Figure 3 ■

Claims (2)

[Claims] (1) A probe composed of a resonant circuit including a piezoelectric vibrator with temperature dependence and an ultrasonic transducer is attached to the inside or surface of the body to be measured, and electromagnetic waves are irradiated to the probe from outside the body. The ultrasonic transducer is controlled by a current flowing through the piezoelectric vibrator when it resonates to generate ultrasonic waves, and the temperature is measured by observing the ultrasonic waves from outside the body. Method of measuring contact temperature, etc. (2) A non-contact temperature type according to claim 1, characterized in that the ultrasonic transducer of the probe has temperature dependence, and the piezoelectric vibrator is removed to form a resonant circuit. etc. measurement method.