JPH03293526A - Non-infiltration temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To measure a temperature of an organism accurately by arranging a temperature detection means for detecting the temperature of a transmission line, a memory means and a correction means. CONSTITUTION:When an antenna 2 is brought into contact with an organism 1, a temperature thereof is measured with a radio meter 5. A control section 10 picks up a measured temperature Tref of the radio meter 5 and a temperature distribution of a coaxial cable (transmission line) 3 to be detected with a thermometer 15. Moreover, at a pre-measurement, it reads a measured temperature Tref' of the meter 5, a liquid temperature ture Tw', a temperature distribution Tc(z)' of the cable 3 all stored in a memory 12 and probe data (power reflectance RW, coaxial cable length L and power attenuation rate alpha) corresponding to the type of a probe mounted from among various probe data stored in the memory 12 beforehand. The control section 10 executes a specified computation using latched various data for correction of the measured temperature Tref of the meter 5 to remove effect of power attenuation and heat noises of the coaxial cable 3. Thus, a correct temperature Tobj of the organism 1 is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a non-invasive temperature measuring device that non-invasively measures the temperature of a living body by receiving microwaves emitted from an object to be measured, such as a living body.

[Prior Art] As a means of measuring the temperature of a living body, a technique for measuring temperature from within a body cavity using an intrabody cavity probe is disclosed in Japanese Patent Application No. 1-691.
No. 75.

In addition, a technology was developed in the 1980s to receive microwaves emitted from a living body using an antenna as the brightness temperature of the living body, supply the received signal to a radiometer via a transmission line, and measure the temperature of the living body through processing by the radiometer. It is shown in the publication No.-46648.

In addition, in the latter method, which captures microwaves and measures brightness temperature, the microwaves emitted from the living body are weak and the level of the received signal is very low, so the received signal is a background signal in the processing system. Sufficient measures have been taken in the radiometer to prevent it from being buried in noise.

[Problem to be solved by the invention] However, even if the background noise of the processing system can be canceled, the power attenuation and thermal noise of the transmission line connecting the antenna and the radiometer cannot be canceled. The reality is that it is not possible.

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

[Means for Solving Problem R] This invention receives microwaves emitted from an object to be measured using an antenna, supplies the received signal to a radiometer via a transmission line, and uses the radiometer to detect the object to be measured. A non-invasive temperature measuring device that measures temperature includes a temperature detection means that detects the temperature of the transmission line, a power reflectance at the interface between the antenna and the object to be measured, and a length of the transmission line;
The apparatus includes a storage means for storing a power attenuation rate, and a correction means for correcting the temperature measured by the radiometer based on the stored contents of the storage means and the temperature detected by the temperature detection means.

[Operation] Microwaves emitted from the object to be measured are received by the antenna, and the received signal is supplied to the radiometer via the transmission line. Then, the temperature of the object to be measured is measured by signal processing of the radiometer.

However, at this time, the temperature of the transmission line is detected by the temperature detection means. Further, the power reflectance, the length of the transmission line, and the power attenuation rate between the antenna and the object to be measured are stored in the storage means, and based on the stored contents and the temperature detected by the temperature detection means, the radio The temperature measured by the meter is corrected.

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

[Example 1] An example of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a living body which is an object to be measured, and a body surface contact type antenna 2 is brought into contact with the surface of the living body 1.

This antenna 2 receives (and transmits) microwaves, and together with a transmission line, for example, a coaxial cable 3, forms a probe, and the coaxial cable 3 is connected to a radiometer 5 by a connector 4.

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

4b.

That is, the type of probe can be determined by detecting the open and closed states of the switches 4a and 4b. Note that if the probes with both the switches 4a and 4b in the open state are not present, it can be determined that the connector 4 has been forgotten when both the switches 4a and 4b are in the open state.

The radiometer 5 measures the brightness temperature of the living body 1 by taking in the received signal of the antenna 2 via the coaxial cable 3 and the connector 4 and processing the received signal.

The measurement results of the radiometer 5 are supplied to the control section 10.

The control unit 10 performs overall control of the device,
Consists of a microcomputer and its peripheral circuits.

An input section 11, a memory 12 as a storage means, a display section 13, a constant temperature bath for calibration 14, and a thermometer 15 as a temperature detection means are connected to the control section 10.

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

The memory 12 is also connected to the radiometer 5, the human power unit 11, and the thermometer 15, and sequentially stores the measured temperature of the radiometer 5, the probe data input from the input unit 11, and the detected temperature of the thermometer 15. It is something to remember.

Furthermore, the memory 12 stores the antenna 2 and a calibration pressure constant temperature bath 14 (described later) as probe data related to the probe.
The power reflection coefficient Rw between the internal liquid and the liquid.

The length of the coaxial cable 3 and the power attenuation rate α are stored for a plurality of types of probes.

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

The calibration constant temperature bath 14 houses 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 constant temperature bath 14, and also detects the temperature distribution Tc (z) of the coaxial cable 3 using a multi-point temperature sensor 16.

That is, the multi-point temperature sensor 16 includes a plurality of temperature sensing parts 16a.
are arranged in a line at predetermined intervals, and are attached to the outer periphery of the coaxial cable 3 and along the axial direction of the coaxial cable 3.

The control unit 10 controls the heating of the constant temperature chamber 14 for calibration while monitoring the temperature detected by the thermometer 15, and includes functional means for maintaining the temperature of the liquid in the constant temperature chamber 14 at a predetermined value, and a radio. Switch 4a of connector 4 through meter 5,
a functional means for monitoring the open/closed state of the 4b and determining the type of probe; a functional means for reading the type of probe data corresponding to the above-mentioned determination result from among the various types of probe data stored in the memory 12; and a thermometer. 15, a functional means for capturing the temperature distribution Tc (z) of the coaxial cable 3, a means for capturing the measured temperature T ref of the radiometer 5, and a function means for capturing the measured temperature T ref from the above-mentioned probe data and temperature distribution Tc ( functional means for correcting based on z);
The temperature Tobj obtained by this correction is displayed on the display section 13 as the brightness temperature of the living body 1.

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 generated from the local oscillator 23, and conducts between the coaxial cable 3 and the port of the circulator 22 when turned on.

The circulator 22 has three ports',
For those ports, isolators 24 . Reference noise source 25. and the above-mentioned DICKE switch 21 are respectively connected.

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

The output of the mixer 27 is supplied to a detector 30 via an IF amplifier 29, detected there, and then supplied to a 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 the voltage level of the signal input manually when the DICKE switch 21 is on is different from the voltage level when the DICKE switch 21 is turned on. It outputs a voltage signal with a level proportional to the difference from the voltage level of the input signal.

The output of this lock-in amplifier 31 is supplied to a control section 32.

The control unit 32 adjusts the reference noise source 25 so that the output voltage of the lock-in amplifier 31 becomes zero level (minimum resolution value).
The noise temperature is controlled and the noise temperature when it reaches zero level is output as the measured temperature.

Next, the operation in the above configuration will be explained.

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

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

In the radiometer 5, the DICKE switch 21 is on,
It is turned off, and when it is turned on, the above-mentioned received signal is captured.

Further, when the D I CKE switch 21 is turned on, the microwave emitted from the reference noise source 25 is transmitted to the circulator 2.
2. DICKE switch 21. and is sent to the antenna 2 by the coaxial cable 3, and from the antenna 2 the living body 1
released towards.

The emitted microwave is absorbed by the living body 1, and a portion is reflected at the interface between the antenna 2 and the living body 1.

This reflected microwave is received by the antenna 2 together with the microwave emitted by the living body 1, and the received signal is taken in via the DICKE switch 21.

When the DICKE switch 21 is off, the reference noise source 2
Only the microwave emitted from the circulator 22
taken in through.

Therefore, if the temperature of the living body 1 is Tt, then the temperature of the antenna 2 and the living body 1 is Tt.
If the power reflectance at the interface with The amount reflected (Tt-
R), which becomes Tt-Tt-R.

The amount of energy of the microwave emitted from the antenna 2, reflected at the boundary surface, and entering the antenna 2 again is TrllR.

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

Further, the amount of energy that enters the lock-in amplifier 31 when the DICKE switch 21 is turned off is Tr.

On the other hand, the control section 32 adjusts the reference noise temperature Tr of the reference noise source 25 by the functions of the lock-in amplifier 31 and the control section 32 so that the amount of energy input when the power is turned on is equal to the amount of energy input when the power is turned off.

In other words, (Tt-Tt-R)+(Tr-R)-Tr.

This is T t+R(Tr-Tt)-Tr, which is T t-T
It is r.

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

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

Furthermore, since the microwave emitted from the living body 1 is 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 Since the lock-in amplifier 31 is divided into two systems synchronized with the on and off states of the DICKE switch 21, and the difference between the two systems is detected, the background noise of both systems is canceled out, and the above-mentioned concerns arise. There isn't.

For the detailed principle of the explanation of the action up to this point, please refer to
It is described in No. 2-269029.

Next, the overall operation will be explained.

The input unit 11 performs an operation to start preliminary measurement.

Then, the control unit 10 starts the heating operation of the constant temperature chamber 14 for calibration, controls the heating while monitoring the temperature detected by the thermometer 15, and brings the temperature of the liquid in the constant temperature chamber 14 for calibration to a predetermined value. maintain.

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

Here, when a storage command is inputted at the input unit 11, the measured temperature T rer' of the radiometer 5, the liquid temperature TW' detected by the thermometer 15, and the temperature distribution Tc of the coaxial cable 3 also detected by the thermometer 15. (z)' are stored in the memory 12, respectively.

Note that Z is the position of the coaxial cable 3 in the axial direction as shown in FIG.

Further, the input unit 11 is used to perform an operation to start the main measurement.

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

At this time, the control unit 10 controls the total 7111 of the radiometer 5.
The I temperature Trcf 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' and TwTc(z)' stored in the memory 12 during preliminary measurement, and further selects the attached probe (the antenna 2 and the coaxial cable) from among the various probe data stored in the memory 12 in advance. 3) Probe data (power reflectance Rw) corresponding to the type.

Read the coaxial cable length and power attenuation rate α).

Then, the control unit 10 executes the calculation of the following formula using the various data taken in, thereby correcting the measured temperature T ref of the radiometer 5 and eliminating the influence of power attenuation and thermal noise of the coaxial cable 3. Correct temperature T obj of living body 1 after removal
seek.

In addition, [ΔTc(z)=Tc(z)−Tc(z)']
It is.

This equation corresponds to equation (10) described in the literature of Institute of Electronics, Information and Communication Engineers EMCJ 88-71 "Method for reducing brightness temperature measurement error of medical radiometer".

The determined temperature T obj of the living body 1 is displayed on the display unit 13 and notified to the user.

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

A second embodiment of the invention will be explained with reference to FIG.

In the drawings, the same parts as in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

Here, the constant temperature bath 14 for calibration is not used, and the processing method of the control unit 10 is different.

The memory 12 also stores power reflectance R between the antenna 2 and the living body 1 as probe data related to the probe.
1 and the length of coaxial cable 3.

Power attenuation rates α are stored for multiple types of probes.

Explain the action.

The human power section 11 performs an operation to start measurement.

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

At this time, the control unit 10 controls the temperature T measured by the radiometer 5.
tel' and the temperature distribution Tc (z) of the coaxial cable 3 detected by the thermometer-15.

Further, the control unit 10 generates probe data (power reflectivity R1 coaxial cable length, power attenuation Rate α
).

Then, the control unit 10 executes the calculation of the following formula using the various data taken in, thereby correcting the measured temperature T ref of the radiometer 5 and eliminating the influence of power attenuation and thermal noise of the coaxial cable 3. Correct temperature T obj of living body 1 after removal
seek.

This formula corresponds to the formula (6) described in the literature of Institute of Electronics, Information and Communication Engineers EMCJ 88-71 "Method for reducing brightness temperature measurement error of medical radiometer".

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 temperature measurement is increased, and reliability can be improved. Moreover, since the type of probe is automatically determined and the probe data is read in accordance with the determination result, the burden on the user is reduced and it is convenient.

In each of the above embodiments, the correction calculation is performed using the probe data stored in the memory 12, or it is also possible to perform the correction calculation using the probe data appropriately input from the input section 11. It is.

Further, in each embodiment, the connector 4 may include a separate connector 20 for notifying the type of probe as shown in FIG. This connector 20 is connected to the line 2
1 is attached to the coaxial cable 3, and a pair of switches 4a for notification.

4b.

Further, in each of the above embodiments, the body surface contact type antenna 2 is used, but a body cavity insertion type antenna 30 shown in FIGS. 6 and 7 may also be used.

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

The coaxial cable 3 is inserted into a tube 31, and a balloon 32 is placed at the end of the tube 31 at a position surrounding the antenna 30.
is provided. Connector 3 is attached to the proximal end of tube 31.
3, a water supply tube 34 is connected to the water supply tube 34, and a water supply pump 35 is connected to the water supply tube 34.

In this case, the tube 31 is first inserted into the body cavity 1a of the living body 1, and the water pump 35 is operated when the antenna 30 at the tip reaches the measurement target site. Then, tube 3
Water is supplied to the balloon 32 through 4.31, and the balloon 32 is inflated and pressed against the body cavity wall, thereby fixing the antenna 30. Thereby, temperature measurement can be performed within the body cavity 1a.

In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without changing the gist.

[Effects of the Invention] As described above, according to the present invention, microwaves emitted from an object to be measured are received by an antenna, the received signal is supplied to a radiometer through a transmission line, and the radiometer detects the object to be measured. A non-invasive temperature measurement device that measures the temperature of an object includes a temperature detection means for detecting the temperature of the transmission line, a power reflectance at the interface between the antenna and the object to be measured, a length of the transmission line, and power attenuation. and a correction means for correcting the temperature measured by the radiometer based on the stored contents of the storage means and the temperature detected by the temperature detection means, so that the antenna and the radiometer can be connected. It is possible to provide a highly reliable non-invasive temperature measuring device that can accurately measure the temperature of a living body without being affected by power attenuation and thermal noise of transmission lines.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a connector in the same embodiment, and FIG. 3 is a specific configuration diagram of a radiometer in the same embodiment. FIG. 4 is an overall configuration diagram of the 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 the antenna in each of the above embodiments. A schematic configuration diagram of an example, FIG. 7 is a diagram specifically showing FIG. 6. 1... Living body (object to be measured), 2... Antenna, 3.
... Coaxial cable (transmission line) 5 ... Radiometer,
10...control unit, 12...memory (storage means) 14
... Calibration constant temperature bath, 15... Thermometer (temperature detection means).

Claims (1)

[Claims] In a non-invasive temperature measurement device that receives microwaves emitted from an object to be measured using an antenna, supplies the received signal to a radiometer via a transmission line, and measures the temperature of the object to be measured by the radiometer, the above-mentioned transmission line is used. temperature detection means for detecting the temperature of the antenna, storage means for storing the power reflectance of the interface between the antenna and the object to be measured, the length of the transmission line, and the power attenuation rate; and the storage contents of the storage means and the above. A non-invasive temperature measuring device comprising: a correction means for correcting the temperature measured by the radiometer based on the temperature detected by the temperature detection means.