JP3021531B2 - Non-invasive temperature measurement device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-invasive temperature measurement apparatus that non-invasively measures the temperature of a living body by receiving a measurement object, for example, a microwave emitted from a living body.

[Prior Art] As a means for measuring the temperature of a living body, a technique of measuring a temperature from the inside of a body cavity using an intracavity probe is disclosed in Japanese Patent Application No. 1-6917.
It is shown in issue 5.

In addition, the technology of receiving microwaves emitted from the living body as the brightness temperature of the living body with an antenna, supplying the received signal to a radiometer through a transmission line, and measuring the temperature of the living body by processing the radiometer is disclosed in -46648.

In the case of measuring the luminance temperature by capturing the microwave as in the latter case, since the microwave emitted from the living body is weak and the level of the received signal is extremely small, the received signal is used as the background of the processing system. Sufficient measures are taken in the radiometer so that it is not buried in noise.

[Problems to be Solved by the Invention] However, even if the background noise of the processing system can be canceled, it cancels the previous portion, that is, the power attenuation and thermal noise of the transmission line connecting the antenna and the radiometer. The reality is that you cannot do that.

The present invention has been made in consideration of the above circumstances, and has as its object to accurately measure the temperature of a living body without being affected by power attenuation and thermal noise of a transmission line connecting an antenna and a radiometer. It is an object of the present invention to provide a highly reliable non-invasive temperature measuring device that can measure well.

[Means for Solving the Problems] A non-invasive temperature measuring device according to the present invention includes an antenna for receiving microwaves emitted from a measurement target, and a transmission connected to the antenna and transmitting a received signal received by the antenna. And a radiometer connected to the transmission line and measuring the temperature of the object to be measured from a reception signal supplied from the antenna, and arranged at predetermined intervals along the axial direction of the transmission line. A multi-point temperature sensor, a temperature detecting means for detecting the temperature distribution of the transmission line by the multi-point temperature sensor, a power reflectance at a boundary surface between the antenna and the object to be measured, a length of the transmission line, and a power A storage unit that stores the attenuation rate; and a correction unit that corrects the measured temperature of the radiometer based on the storage content of the storage unit and the temperature detected by the temperature detection unit.

[Operation] The microwave emitted from the object to be measured is received by the antenna, and the received signal is supplied to the radiometer via the transmission line. And by the signal processing of the radiometer,
The temperature of the measurement object is measured.

However, at this time, the temperature distribution along the axial direction of the transmission line is detected by the temperature detecting means. In addition, the power reflectivity between the antenna and the object to be measured, the length of the transmission line, and the power decay rate are stored in the storage means, and based on the stored contents and the temperature detected by the temperature detection means, The temperature measured by the meter is corrected.

This correction removes the effects of power attenuation and thermal noise on the transmission line connecting the antenna and the radiometer.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a living body which is a measurement object, and a body surface contact type antenna 2 is brought into contact with the surface of the living body 1.

The antenna 2 receives (and transmits) microwaves, connects a transmission line such as a coaxial cable 3 and forms a probe together with the coaxial cable 3, and the coaxial cable 3 is connected to a radiometer 5 by a connector 4. It is connected.

As shown in FIG. 2, the connector 4 has a pair of switches 4a and 4b as a probe type notification function for causing the connected device to determine the type of the probe.

That is, the type of the probe can be determined by detecting the open / closed state of the switches 4a and 4b. If the probes in which both the switches 4a and 4b are open are not present, it is possible to determine that the connector 4 has been forgotten when both the switches 4a and 4b are open.

The radiometer 5 receives a signal received by the antenna 2 via the coaxial cable 3 and the connector 4 and processes the received signal to measure the brightness temperature of the living body 1.

The measurement result of the radiometer 5 is supplied to the control unit 10.

The control unit 10 controls the entire device,
It consists of a microcomputer and its peripheral circuits.

The control unit 10 includes an input unit 11 and a memory 1 serving as a storage unit.
2. A display unit 13, a calibration thermostat 14, and a thermometer 15 as a temperature detecting means are connected.

The input unit 11 includes a switch and a keyboard, and is used for setting an operation mode and inputting probe data related to the probe.

The memory 12 is also connected to the radiometer 5, the input unit 11, and the thermometer 15.
Probe data and thermometer input from input unit 11
The 15 detected temperatures are sequentially stored.

Further, the memory 12 stores, as probe data relating to the probe, a power reflectivity Rw of a boundary surface between the antenna 2 and a liquid in a calibration thermostat 14, which will be described later, a length L of the coaxial cable 3, and a power attenuation rate α. Are stored for multiple types of probes.

The display unit 13 displays the calculation result of the control unit 10 (measured temperature after correction).

The calibration thermostat 14 contains a liquid (water) therein and heats the liquid in accordance with a command from the control unit 10.

The thermometer 15 detects the temperature Tw of the liquid in the calibration thermostat 14 and detects the temperature distribution Tc (z) of the coaxial cable 3 by the multipoint temperature sensor 16.

In other words, the multi-point temperature sensor 16 has a plurality of temperature sensing sections 16a arranged in a line at predetermined intervals.
And mounted along the axial direction of the coaxial cable 3.

The control unit 10 controls the heating of the calibration thermostat 14 while monitoring the temperature detected by the thermometer 15, and the calibration thermostat 14
A functional means for maintaining the temperature of the liquid in 14 at a predetermined value, a functional means for monitoring the open / close state of switches 4a and 4b of connector 4 through radiometer 5, and determining the type of probe;
A function for reading probe data of a type corresponding to the above-described determination result among various types of probe data stored in the memory 12, and a temperature distribution Tc of the coaxial cable 3 from the thermometer 15;
(Z) Functional means for taking in and the temperature measured by the radiometer 5
Means for taking in Tref, functional means for correcting the measured temperature Tref based on the probe data and temperature distribution Tc (z) taken in, and the temperature Tobj obtained by this correction as the brightness temperature of the living body 1 Function means for displaying on the display unit 13.

 On the other hand, a specific example of the radiometer 5 is shown in FIG.

A port of a circulator 22 is connected to the coaxial cable 3 via a DICKE switch 21.

The DICKE switch 21 is turned on and off by a rectangular wave signal emitted from the local oscillator 23.
And the port of the circulator 22.

The circulator 22 has three ports, and the isolator 2 is connected to these ports in the order of signal transmission.
4. The reference noise source 25 and the DICKE switch 21 are respectively connected.

The output of the isolator 24 is supplied to a mixer 27 via an RF amplifier 26.
Supplied to The mixer 27 multiplies the output of the RF amplifier 26 by the output of the local oscillator 28.

The output of the mixer 27 is supplied to the detector 30 via the IF amplifier 29, where it is detected and supplied to the lock-in amplifier 31.

The lock-in amplifier 31 synchronizes the ON / OFF of the DICKE switch 21 based on the rectangular wave signal of the local oscillator 23, and sets the voltage level of the signal input when the DICKE switch 21 is ON and the signal input when the DICKE switch 21 is OFF. And outputs a voltage signal having a level proportional to the difference between the voltage levels.

The output of the lock-in amplifier 31 is supplied to the control unit 32.

The control unit 32 controls the noise temperature of the reference noise source 25 so that the output voltage of the lock-in amplifier 31 becomes a zero level (minimum resolution value), and outputs the noise temperature when the zero level is reached as a measured temperature. Is what you do.

 Next, the operation of the above configuration will be described.

 First, the processing of the radiometer 5 will be described.

The living body 1 emits microwaves, and the microwaves are received by the antenna 2. This received signal is sent to the radiometer 5 by the coaxial cable 3.

In the radiometer 5, the DICKE switch 21 is turned on and off, and when the DICKE switch 21 is turned on, the reception signal is taken.

Further, when the DICKE switch 21 is turned on, the microwave emitted from the reference noise source 25 is sent to the antenna 2 by the circulator 22, the DICKE switch 21, and the coaxial cable 3, and emitted from the antenna 2 toward the living body 1.

The emitted microwave is absorbed by the living body 1 and a part thereof is reflected on the boundary surface between the antenna 2 and the living body 1. This reflected microwave is received by the antenna 2 together with the emitted microwave of the living body 1, and the received signal is taken in via the DICKE switch 21.

When the DICKE switch 21 is off, only the microwave emitted from the reference noise source 25 is taken in through the circulator 22.

Therefore, the temperature of the living body 1 is Tt, the antenna 2 and the living body 1
Assuming that the power reflectance at the boundary surface with R is R and the reference noise temperature emitted from the reference noise source 25 is Tr, the amount of microwave energy emitted from the living body 1 and entering the antenna 2 is within the living body 1 at the boundary surface. Minutes (Tt ・
R), Tt−Tt · R.

The amount of energy of the microwave emitted from the antenna 2 and reflected at the boundary surface and reentering the antenna 2 is Tr · R.

From this, the amount of energy that enters the lock-in amplifier 31 when the DICKE switch 21 is turned on is (Tt−Tt · R) + (Tr · R).

When the DICKE switch 21 is turned off, the lock-in amplifier 3
The amount of energy entering 1 is Tr.

On the other hand, the operation of the lock-in amplifier 31 and the control unit 32 adjusts the reference noise temperature Tr of the reference noise source 25 by the control unit 32 such that the amount of energy entering at the time of ON and the amount of energy entering at the time of OFF become the same.

 That is, (Tt−Tt · R) + (Tr · R) = Tr.

 This is Tt + R (Tr-Tt) = Tr, and Tt = Tr.

At this time, the control unit 32 captures the reference noise temperature Tr as the temperature Tt of the living body 1 as it is.

That is, the temperature Tt of the living body 1 can be directly measured irrespective of the power reflectivity R at the interface between the antenna 2 and the living body 1.

Since the microwaves emitted from the living body 1 are weak, there is a concern that the received signal may be buried in the background noise of the processing system after the DICKE switch 21, but the processing system is locked in. The amplifier 31 is divided into two systems synchronized with the ON and OFF of the DICKE switch 21, and the difference between the two systems is detected. Therefore, the background noise of the two systems is cancelled, and there is no concern about the above. .

The detailed principle of the operation description so far is described in
62-269029.

 Next, the overall operation will be described.

 The input unit 11 performs a preliminary measurement start operation.

Then, the control unit 10 starts the heating operation of the calibration thermostat 14, controls the heating while monitoring the detection temperature of the thermometer 15, and sets the temperature of the liquid in the calibration thermostat 14 to a predetermined value. maintain.

In this state, when the antenna 2 is brought into contact with the liquid surface in the calibration thermostat 14, the temperature of the liquid is measured by the radiometer 5.

Here, when a storage command is input through the input unit 11, the measured temperature Tref 'of the radiometer 5, the liquid temperature Tw' detected by the thermometer 15, and the temperature distribution Tc of the coaxial cable 3 similarly detected by the thermometer 15 are obtained. (Z) ′ are stored in the memory 12.

Here, z is the axial position of the coaxial cable 3 as shown in FIG.

 Further, the input unit 11 performs an operation for starting the main measurement.

When the antenna 2 is brought into contact with the living body 1, the living body 1
Is measured by the radiometer 5.

At this time, the control unit 10 determines the measured temperature Tr of the radiometer 5
ef and the temperature distribution Tc (z) of the coaxial cable 3 detected by the thermometer 15 are taken.

Further, the control unit 10 reads Tref ', Tw', and Tc (z) 'stored in the memory 12 at the time of the preliminary measurement, and further reads the memory 12
The probe data (power reflectance Rw, coaxial cable length L, power attenuation rate α) corresponding to the type of the attached probe (antenna 2 and coaxial cable 3) is read from among various types of probe data stored in advance.

Then, the control unit 10 executes the calculation of the following expression using the various data taken in, thereby correcting the measured temperature Tref of the radiometer 5 and removing the influence of power attenuation and thermal noise of the coaxial cable 3. Then, the correct temperature Tobj of the living body 1 is obtained.

This equation is described in the literature of the IEICE EMCJ88-71, “Method for reducing the error in measuring the brightness temperature of medical radiometers” (1).
0).

The obtained temperature Tobj of the living body 1 is displayed on the display unit 13 and notified to the user.

Therefore, the accuracy of the temperature measurement is improved, and the reliability can be improved. Moreover, the type of probe is automatically determined,
Since the probe data is read in accordance with the discrimination result, the burden on the user is reduced, which is convenient.

A second embodiment of the present invention will be described with reference to FIG. In the drawings, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

Here, the calibration thermostat 14 is not used, and the control
10 processing methods are different.

Further, the memory 12 stores, as probe data relating to the above-mentioned probes, the power reflectance R of the interface between the antenna 2 and the living body 1, the length L of the coaxial cable 3, and the power attenuation rate α for a plurality of types of probes. ing.

 The operation will be described.

 The input unit 11 performs an operation for starting measurement.

When the antenna 2 is brought into contact with the living body 1, the living body 1
Is measured by the radiometer 5.

At this time, the control unit 10 determines the measured temperature Tr of the radiometer 5
ef and the temperature distribution Tc (z) of the coaxial cable 3 detected by the thermometer 15 are taken.

Further, the control unit 10 determines a mounting probe (antenna 2) from various probe data stored in the memory 12 in advance.
And probe data (power reflectance R, coaxial cable length L, power attenuation rate α) corresponding to the type of coaxial cable 3) is read.

Then, the control unit 10 executes the calculation of the following equation using the various data taken in, thereby correcting the measured temperature Tref of the radiometer 5 and removing the influence of power attenuation and thermal noise of the coaxial cable 3. Then, the correct temperature Tobj of the living body 1 is obtained.

This equation corresponds to the equation (6) described in the literature of the IEICE EMCJ88-71, “Method for Reducing the Brightness Temperature Measurement Error of Medical Radiometers”.

The obtained temperature Tobj of the living body 1 is displayed on the display unit 13 and notified to the user.

Therefore, the accuracy of the temperature measurement is improved, and the reliability can be improved. Moreover, the type of probe is automatically determined,
Since the probe data is read in accordance with the discrimination result, the burden on the user is reduced, which is convenient.

In each of the above embodiments, the correction operation is performed using the probe data stored in the memory 12. However, the correction operation can be performed using the probe data appropriately input from the input unit 11. It is.

In each embodiment, the connector 4 is the fifth connector.
As shown in the figure, a connector provided with a probe type notification connector 20 may be separately provided. The connector 20 is attached to the coaxial cable 3 by a line 21 and has a pair of switches 4a and 4b for notification.

Further, in each of the above embodiments, the antenna 2 of the body surface contact type is used.
However, the antenna 30 of the type inserted into the body cavity shown in FIGS. 6 and 7 may be used.

That is, the antenna 30 is attached to the end of the coaxial cable 3, and the radiometer 5 (not shown) is connected to the base end of the coaxial cable 3.

The coaxial cable 3 is inserted through a tube 31, and a balloon 32 is provided at a position surrounding the antenna 30 at the end of the tube 31. A water supply tube 34 is connected to a base end of the tube 31 via a connector 33, and a water supply pump 35 is connected to the water supply tube 34.

In this case, first, the tube 31 is inserted into the body cavity 1a of the living body 1, and when the antenna 30 at the tip reaches the measurement target site, the water supply pump 35 is operated. Then, water is supplied to the balloon 32 through the tubes 34 and 31, and the balloon 32 expands and presses against the body cavity wall, thereby fixing the antenna 30.
Thereby, the temperature can be measured in the body cavity 1a.

In addition, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

[Effects of the Invention] As described above, according to the present invention, an antenna for receiving microwaves emitted from an object to be measured, a transmission line connected to the antenna and transmitting a received signal received by the antenna, A non-invasive temperature measuring device having a radiometer connected to the transmission line and measuring the temperature of the object to be measured from a reception signal supplied from the antenna, are arranged at predetermined intervals along the axial direction of the transmission line A multi-point temperature sensor; a temperature detecting means for detecting a temperature distribution of the transmission line by the multi-point temperature sensor; a power reflectance at a boundary surface between the antenna and the object to be measured; a length of the transmission line; Storage means for storing the rate, and correction means for correcting the measured temperature of the radiometer based on the storage content of the storage means and the temperature detected by the temperature detection means, A highly reliable non-invasive temperature measurement device capable of accurately measuring the temperature of a living body without being affected by power attenuation and thermal noise of a transmission line connecting an antenna and a radiometer can be provided.

[Brief description of the drawings]

1 is an overall configuration diagram of one embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a connector in the embodiment, FIG. 3 is a specific configuration diagram of a radiometer in the embodiment, FIG. 4 is an overall configuration diagram of a second embodiment of the present invention, FIG. 5 is a schematic configuration diagram of a modification of the connector in each of the above embodiments, and FIG. 6 is a modification of an antenna in each of the above embodiments. FIG. 7 is a schematic configuration diagram of an example, and FIG. 7 is a diagram specifically showing FIG. DESCRIPTION OF SYMBOLS 1 ... living body (measurement object), 2 ... antenna, 3 ... coaxial cable (transmission line), 5 ... radiometer, 10 ... control part, 12 ... memory (storage means), 14 ... calibration Thermostat, 15 ... thermometer (temperature detection means).

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-22636 (JP, A) JP-A-1-58178 (JP, U) JP-B-60-46648 (JP, B2) Corona “Microwave Circuits, 7th edition (1965) pp. 38-45 (58) Fields investigated (Int. Cl. ⁷ , DB name) G01J 5/00-5/62

Claims (1)

(57) [Claims] An antenna for receiving microwaves emitted from an object to be measured, a transmission line connected to the antenna and transmitting a received signal received by the antenna, and a transmission line connected to the transmission line and supplied from the antenna. A non-invasive temperature measuring device having a radiometer for measuring the temperature of the object to be measured from a received signal, wherein the multi-point temperature sensor is disposed at a predetermined interval along the axial direction of the transmission line; Temperature detecting means for detecting the temperature distribution of the transmission line by means of the above; storage means for storing the power reflectance at the interface between the antenna and the object to be measured, the length of the transmission line, and the power attenuation rate; Correction means for correcting the measured temperature of the radiometer based on the stored contents of the above and the temperature detected by the temperature detection means.