JPH05253239A - Heating unit - Google Patents

Abstract

PURPOSE:To provide a reliable heating unit capable of making a part to be heated coincide with a part at which to measure temperature irrespective of the kind of an antenna used, while enabling proper heating output control. CONSTITUTION:A heating means is provided by which microwaves emitted from a magnetron 10 are released from an antenna 1. A measuring means is provided which receives at the antenna 1 microwaves emitted from a living body and measures the temperature of the living body in a non-invasive manner by means of a radiometer. The measuring means includes an oscillation means for setting a measuring frequency, the same magnetron 10 as the heating means being employed as the oscillation means. The measuring frequency of the measuring means is thereby set to the same value as the microwave frequency of the heating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for heating a diseased part of a living body with microwaves.

[0002]

2. Description of the Related Art There is a technique for irradiating microwaves inside a body cavity to heat a deep part of a living body. For example, JP-A-3-121
No. 74 publication.

In such body-cavity heating, an intra-body-cavity applicator having an antenna at its tip is used. The antenna of the intra-body-cavity applicator is commonly used for non-invasive temperature measurement by a radiometer to provide a heating function. Some have a temperature measurement function. For example, it is shown in JP-A-2-252469. Even in the case of extracorporeal heating, there are some which perform both heating and temperature measurement using the same antenna.
For example, it is shown in 1982 IEEE MMT-S Digest V-2.

In this extracorporeal heating, there is also one that can estimate the temperature distribution in the depth direction of the living body by using a multi-frequency radiometer for temperature measurement. For example, 1990 IEEE MTT-S Dige
Shown in stM-5.

[0005]

In the example of the intracorporeal warming described above, there is an advantage that the intracorporeal applicator can be downsized by sharing the antenna of the intracorporeal applicator for heating and temperature measurement. is there.

However, if the microwave frequency for heating and the frequency for temperature measurement are different, the radiation distribution of the antenna during heating and the reception distribution of the antenna during temperature measurement are different. This leads to a positional shift between the heated portion and the temperature measured portion, which adversely affects the heating output control.

In the above example of the external heating, the waveguide type antenna in which the radiation distribution and the reception distribution do not largely change even if there is a difference in frequency is used, and the above problems do not occur.

The present invention takes the above circumstances into consideration,
The aim is to provide a highly reliable heating device that can match the heating part with the temperature measurement part regardless of the type of antenna and enables appropriate heating output control. To do.

[0009]

The heating device of the present invention comprises:
A heating means for emitting a microwave for heating from an antenna, a microwave for receiving a microwave emitted from a measurement object by the antenna, and a measurement means for non-invasively measuring the temperature of the measurement object by a radiometer, There is provided an oscillating means for setting the measuring frequency of the measuring means and the microwave frequency of the heating means to the same value.

[0010]

[Function] The radiation distribution of the antenna during heating and the reception distribution of the antenna during temperature measurement are the same.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes an antenna, which is provided at the tip of an in-body applicator to be inserted into the body cavity. The antenna 1 is connected to a coaxial switch 3 via a coaxial cable 2, and a heating coaxial cable 4 and a temperature measuring coaxial cable 5 are connected to the coaxial switch 3.

The coaxial switch 3 functions to selectively switch the connection between the coaxial cable 2 and the coaxial cable 4 and the connection between the coaxial cable 2 and the coaxial cable 5 in response to a command from the control unit 40 described later. Reference numeral 10 denotes a magnetron, which is an oscillating means, and is driven by a magnetron drive control unit 11 to emit a microwave of a predetermined frequency.

The magnetron drive controller 11 controls the output (microwave power) of the magnetron 10 at the same time as turning on and off the operation of the magnetron 10 in response to a command from the controller 40 described later.

The microwave emitted from the magnetron 10 is sent to the distributor 12. The distributor 12 functions to send most of the electric power of the incident microwaves to the coaxial cable 4 and send a small part of the remaining power to the variable attenuator 28.

The antenna 1, the coaxial cable 2, the coaxial switch 3, the coaxial cable 4, the magnetron 10, the magnetron drive controller 11, the distributor 12, and the controller 4 which will be described later.
0 constitutes heating means for emitting microwaves for heating from the antenna 1.

On the other hand, a radiometer is connected to the coaxial cable 5. This radiometer is a Dicke
It is composed of a series of components from the switch 21 to the lock-in amplifier 31, and the received signal of the antenna 1 is captured and processed to measure the brightness temperature of the measurement object, for example, a living body. The measurement result of this radiometer is sent to the control unit 40. The radiometer will be described below. The port of the circulator 22 is connected to the coaxial cable 5 via the Dicki switch 21.

The Dickie switch 21 is repeatedly turned on and off by the rectangular wave signal generated from the synchronizing signal generator 23, and when it is turned on, the coaxial cable 5 and the circulator 22 are turned on.
Conduct between the two.

The circulator 22 has three ports and has an isolator 24, a reference temperature thermal noise source 25, and the Dicky switch 21 in the order of signal transmission.
Are connected respectively.

The output of the isolator 24 is the RF amplifier 26.
Is supplied to the mixer 27 via. This mixer 27
The output of the RF amplifier 26 is multiplied by the output of the variable attenuator 28 input to the LO terminal to perform frequency conversion. That is, the frequency of the microwave output from the variable attenuator 28 becomes the measurement frequency (= center frequency). The variable attenuator 28 attenuates the electric power of the microwave supplied from the distributor 12 with an attenuation amount according to a command from the control unit 40. The output of the mixer 27 is supplied to the wave detector 30 via the IF amplifier 29, detected there, and then supplied to the lock-in amplifier 31.

The lock-in amplifier 31 operates on the basis of the rectangular wave signal of the synchronizing signal generator 23 to output the Dicky switch 2
A voltage signal proportional to the difference between the signal voltage input when the Dickie switch 21 is turned on and the signal voltage input when the Dicky switch 21 is turned off is output in synchronization with the on / off of 1. The output of the lock-in amplifier 31 is supplied to the control unit 40.

The control unit 40 comprises a microcomputer and its peripheral circuits, and controls the reference noise temperature of the reference temperature thermal noise source 25 so that the output voltage of the lock-in amplifier 31 becomes zero level (minimum resolution value). , The reference noise temperature when it reaches zero level is output as the measured temperature.

A multipoint temperature sensor 51 is attached to the coaxial cable 2, a temperature sensor 52 is attached to the coaxial switch 3, and a multipoint temperature sensor 53 is attached to the coaxial cable 5. Then, these temperature sensors 51, 52, 53 are connected to the thermometer 50.

The multipoint temperature sensors 51, 53 are a plurality of temperature sensitive parts, for example, thermocouples arranged in a line at predetermined intervals, and are attached to the outer periphery of the coaxial cable and along the axial direction of the coaxial cable.

The thermometer 50 detects the temperature of the liquid in the calibration thermostat (not shown), the multipoint temperature sensors 51 and 53 detect the temperature distribution of the coaxial cables 2 and 5, and the temperature sensor 52 detects the temperature distribution. The temperature of the coaxial switch 3 is detected. The detection result is sent to the control unit 40.

By the antenna 1, the coaxial cable 2, the coaxial switch 3, the coaxial cable 5, the radiometer, the control unit 40, the thermometer 50, and the temperature sensors 51, 52, 53,
Measuring means is configured. Next, the operation of the above configuration will be described.

In the control unit 40, the temperature measurement timing and the heating timing are alternately determined. The coaxial switch 3 responds to this, the coaxial cable 2 and the coaxial cable 5 are conducted at the temperature measurement timing, and the coaxial cable 2 and the coaxial cable 4 are conducted at the heating timing. At the temperature measurement timing, the radiometer executes the next temperature measurement process.

At this time, the magnetron 10 is driven,
A microwave of a predetermined frequency is emitted. This microwave is sent to the variable attenuator 28 of the radiometer and becomes a measurement frequency signal. The control unit 40 adjusts the amount of attenuation of the variable attenuator 28 by following the output control for the magnetron 10 and always maintains the power level of the measurement frequency signal constant.

In the radiometer, Dickie switch 2
When 1 is turned on, microwaves emitted from the reference temperature thermal noise source 25 are circulator 22, Dickie switch 2
1, sent to the antenna 1 through the coaxial cable 5, the coaxial switch 3, and the coaxial cable 2, and emitted from the antenna 1 toward the living body.

The emitted microwaves are absorbed by the living body and are partially reflected by the interface between the antenna 1 and the living body. This reflected microwave is received by the antenna 1 together with the emitted microwave of the living body itself, and the received signal is taken in via the Dickie switch 21. Dicki
When the switch 21 is off, only microwaves emitted from the reference temperature thermal noise source 25 are taken in through the circulator 22.

Therefore, the temperature of the living body is Tobj, the power reflectivity of the interface between the antenna 1 and the living body is R, the reference noise temperature emitted from the reference temperature thermal noise source 25 is Tref, and the coaxial cable or connector in the middle Neglecting the reflection and attenuation of T, the amount of energy of the microwave emitted from the living body and entering the antenna 1 is equal to (T
obj * R), and Tobj-Tobj * R. The amount of energy of the microwave emitted from the antenna 1, reflected on the boundary surface, and reentering the antenna 1 is Tref · R. From this, the amount of energy that enters the lock-in amplifier 31 when the Dickie switch 21 is on is (Tobj-Tobj.R) + (Tref.R). The amount of energy that enters the lock-in amplifier 31 when the Dickie switch 21 is off is Tref.

On the other hand, the lock-in amplifier 31 and the control unit 40
By this action, the reference noise temperature Tref of the reference temperature thermal noise source 25 is adjusted so that the amount of energy that enters when it is turned on is the same as the amount of energy that enters when it is turned off. That is, (Tobj-Tobj.R) + (Tref.R) = Tref. This is Tobj + R (Tref-Tobj) = Tref, where R ≠ 1.
Then, Tobj = Tref. At this time, the control unit 40 will directly capture the reference noise temperature Tref as the temperature Tobj of the living body. That is, the temperature Tobj of the living body can be directly measured regardless of the power reflectivity R of the interface between the antenna 1 and the living body.

Since the microwave emitted from the living body is weak, there is a concern that the received signal may be buried in the background noise of the processing system after the Dickie switch 21. Is divided into two systems synchronized with the ON / OFF of the Dickie switch 21 in the lock-in amplifier 31, and the difference between the two systems is detected. Therefore, the background noise of both systems is canceled out. No worries about

Since there is a concern that the temperature fluctuations of the equipment constituting the radiometer may appear as fluctuations in the measured value, the Dickie switch 21 and the RF amplifier 26 are particularly important, and a Peltier element or the like not shown is used. Temperature control.

Further, the temperature fluctuations of the coaxial cables 2 and 5 and the coaxial switch 3 are particularly large, which causes a large variation in the measured values. Therefore, as described above, the temperature sensors 51, 52, 53 and the thermometer 50 are employed, and the control unit 40 performs temperature correction on the measured value based on the temperature detected by the thermometer 50. In this temperature correction, if the temperature of the uniform water temperature of the water tank is measured in advance, the data at that time may be added as the correction data.

Next, at the heating timing, microwaves emitted from the magnetron 10 are passed through the coaxial cable 4, the coaxial switch 3, and the coaxial cable 2 to the antenna 1
And is released to the living body. In this case, based on the measured value obtained at the temperature measurement timing, the magnetron 10
Is controlled, and the temperature of the living body is heated to the temperature required for treatment.

As described above, the magnetron 10 which is the oscillating means is commonly used for heating and temperature measurement, and the heating microwave frequency and the temperature measurement frequency are set to the same value. As a result, the radiation distribution (= directivity) of the antenna 1 during heating and the reception distribution (= directivity) of the antenna 1 during temperature measurement become the same. That is, the heating part and the temperature measuring part in the living body coincide with each other. Therefore, it is possible to reliably capture the temperature of the heated portion, and it is possible to appropriately control the heating output.

Further, even if the oscillation frequency of the magnetron 10 is deviated due to aging, the above effect is secured because the magnetron 10 itself is common for heating and temperature measurement. For reference, an example of how the directivity of the antenna changes depending on the difference in frequency is shown in FIG. 2 for a helical antenna. Like the antenna 1, this helical antenna is a coil, and the solid line represents horizontal polarization and the broken line represents vertical polarization. A second embodiment of the present invention will be described. Here, as shown in FIG. 3, a coaxial switch 61 is adopted in place of the distributor 12, and a fixed type ordinary attenuator 62 is adopted in place of the variable attenuator 28.

The coaxial switch 61 selectively switches between supplying microwaves to the heating-side coaxial cable 4 and supplying microwaves to the temperature measuring-side attenuator 62 in response to a command from the control unit 40. do. The operation will be described.

At the heating timing, the microwave of electric power necessary for heating is emitted from the magnetron 10, sent from the coaxial switch 61 to the coaxial cable 4, and further passed through the coaxial switch 3 and the coaxial cable 2 to the antenna 1
Sent to.

At the temperature measurement timing, the microwave whose power is lowered in advance is emitted from the magnetron 10,
It is sent from the coaxial switch 61 to the attenuator 62, where it is attenuated to a required level and becomes a measurement frequency signal. That is, the control unit 40 controls the microwave power level to be lower than that during heating when measuring the temperature.

With such a configuration, the attenuator 62 is of a fixed attenuation amount type, and the attenuation amount may be small, so that the cost and size of the attenuator can be reduced. Further, while the distributor generally tends to generate a lot of noise generated by itself, the coaxial switch 61 does not have such a problem.

Further, the microwave supply to the radiometer is limited only during temperature measurement, and since the microwave supplied to the radiometer during temperature measurement has low power, the influence of noise on the measurement should be eliminated as much as possible. You can A third embodiment of the present invention will be described.

Here, as shown in FIG. 4, a local oscillator 70 is adopted as the oscillating means in place of the magnetron 10, and an output of the local oscillator 70 is distributed to a power amplifier 72 and an attenuator 73 by a distributor 71. Then, the output of the power amplifier 72 is sent to the coaxial cable 4, and the output of the attenuator 73 is sent to the mixer 28 of the radiometer. Power amplifier 7
Reference numeral 2 is for amplifying the output of the local oscillator 70 to a power level required for heating, and its amplification factor is controlled by the control unit 40. The operation will be described.

At the heating timing, the signal emitted from the local oscillator 70 is sent from the distributor 71 to the power amplifier 72, where it is amplified to the electric power required for heating and sent to the coaxial cable 4, and the coaxial switch 3 and It is sent to the antenna 1 through the coaxial cable 2.

At the temperature measurement timing, the local oscillator 70
From the distributor 71 is sent from the distributor 71 to the attenuator 73, where the sensitivity of the mixer 28 is attenuated to the highest power level and becomes the measurement frequency signal.

According to such a configuration, the attenuator 73 is of a fixed attenuation amount type, and its attenuation amount is only a few dB because the original power level is low. Therefore, the cost of the attenuator is low. Can be reduced and miniaturized. Further, since the local oscillator 70 is used instead of the magnetron 10, the stability of the oscillation frequency is high and the accuracy of the temperature measurement value is improved.

As the oscillating means, both a magnetron and a local oscillator are used if the oscillating frequency is the same.
The magnetron may be operated during heating and the local oscillator may be operated during temperature measurement.

[0049]

As described above, according to the present invention, the radiation distribution of the antenna at the time of heating and the reception distribution of the antenna at the time of measuring the temperature are made to be the same. Therefore, regardless of the type of the antenna, It is possible to provide a heating device with excellent reliability that allows the heating portion and the temperature measurement portion to coincide with each other and enables appropriate heating output control.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of first, second and third embodiments of the present invention.

FIG. 2 is a diagram showing, for reference, an example of how the directivity of an antenna changes depending on the difference in frequency.

FIG. 3 is a diagram showing a configuration of a main part of a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a main part of a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna, 2, 4, 5 ... Coaxial cable, 10 ... Magnetron (oscillating means), 12 ... Distributor, 21-31 ... Radiometer, 40 ... Control part.

Claims (1)

[Claims] 1. A heating means for emitting a microwave for heating from an antenna and a microwave emitted from an object to be measured are received by the antenna, and the temperature of the object to be measured is noninvasively measured by a radiometer. And a oscillating means for setting the measuring frequency of the measuring means and the microwave frequency of the heating means to the same value.