JPH0256107B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field to which the invention pertains] The present invention relates to a heating device for hyperthermia, and in particular, uses electromagnetic waves to locally heat cancer tissue in a living body, thereby heating the cancer tissue. This invention relates to a heating device for hyperthermia that stops the regeneration function and causes death.

[Conventional technology and its problems]

In recent years, treatment methods using hyperthermia (also called "hyperthermia") have been in the spotlight, in particular by continuously heating malignant tumors at around 43 degrees Celsius for one to two hours, and at regular intervals. A number of research reports have been made that by repeating this, it is possible to inhibit the regenerative function of cancer cells and at the same time kill many of them (Measurement and Control Vol. 22, No. 10). This type of heating therapy includes a general heating method and a local heating method. Of these,
As local heating methods for selectively warming only the cancer tissue and its surroundings, methods using electromagnetic waves, methods using electromagnetic induction, methods using ultrasound, and the like have been proposed.

On the other hand, as is already known among researchers in the art, the heating effect on cancer tissue is said to be around 43 [℃], and if it is lower than this, the effect will be diminished, and vice versa. If the concentration is too high, it may harm normal tissues and is not desirable. That is, in hyperthermia, the temperature of the body must be maintained within a narrow temperature range that causes lethal damage to cancerous tissues but does not cause much harm to normal tissues.

[Problem to be solved by the invention]

However, in the conventional technology, deep heating within the body is difficult to achieve by heating the target area due to the specificity of biological functions, such as the cooling effect of blood flow.
It is not easy to maintain a constant temperature of around 43°C for one to two hours. In particular, heating therapy using electromagnetic waves has been abandoned for a long time because the electromagnetic wave absorption rate of the surface of a living body is extremely high, so conventional techniques were considered unsuitable for deep heating.

[Purpose of the invention]

The present invention takes into consideration the disadvantages of the conventional example, and particularly aims to continuously heat the heating area below a predetermined temperature for a certain period of time, and to prevent the temperature from increasing rapidly at the start of heating. It is an object of the present invention to provide a hyperthermia heating device that can effectively prevent adverse effects on surrounding normal tissues.

[Means to solve the problem]

Therefore, the present invention includes an electromagnetic wave generating means that outputs electromagnetic waves, and an applicator that irradiates the living body with the electromagnetic waves output from the electromagnetic wave generating means. Furthermore, a temperature measuring means detects the temperature of the heated area at regular intervals in response to the output of the electromagnetic wave generating means, and when the temperature measuring means detects a biological temperature higher than a preset temperature, the biological temperature is determined. The main control section has an output interruption control function that interrupts and controls the output of the electromagnetic wave generating means until the temperature drops to a predetermined temperature. This main control section operates simultaneously with the output interruption control function and reduces the output level of the electromagnetic wave generating means to 1 every time the temperature measurement means measures the temperature.
The system is equipped with an output drop setting function that controls the output step by step. This aims to achieve the above-mentioned purpose.

[Effect]

When the output of the electromagnetic wave generating means is gradually increased after the applicator is brought into contact with the surface of the heating section, the temperature of the living body surface and the electromagnetic wave irradiated portion inside the living body at the contact surface increases.

In this case, the main control unit activates the output interruption control function and the output drop setting function to control the electromagnetic wave generation means based on the temperature information from the temperature measurement means so that the heating point reaches a predetermined heating temperature. Effectively control output.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is an overall system diagram showing one embodiment of the present invention. In FIG. 1, the hyperthermia heating device includes a microwave generation section 2 as an electromagnetic wave generation section, a control section 4 including first to fourth control functions, and a microwave irradiation section 6. It is organized as a department.

The microwave generator 2 includes a magnetron 8 as an electromagnetic wave generating means, a directional coupler 10 installed on the output side of the magnetron 8, and detects the output level of the magnetron 8 via the directional coupler 10. It consists of a diode 12 as a sensor and a power control unit 14 that adjusts the output of the magnetron 8. Of these, the power control unit 14 is a control circuit that adjusts the output of the magnetron 8 by changing the anode voltage of the magnetron 8 under control using a thyristor.

Further, the directional coupler 10 is a device that separately separates and takes out incident waves and reflected waves, and the electromagnetic waves taken out here are detected by a diode 12, converted into voltage, and then converted to an analog-to-digital converter (hereinafter referred to as , simply referred to as an "A/D converter") 16 to the main control section 18 in the control section 4.

The main control unit 18 calculates the power of the microwave effectively supplied to the applicator 20, which will be described later, by calculating the difference between the power level value of the extracted incident wave and the power level value of the opposite wave. Based on the results, the first to fourth control means in the main control section 18 are operated to control the output of the magnetron 8.

On the other hand, in this embodiment, the microwave irradiation unit 6 includes an applicator 20 that irradiates the living body 32 with microwaves.
and a cooling mechanism 34 for cooling the opening side of the applicator 20, that is, the surface of the living body 32, and is further equipped with a temperature sensor 30 for detecting the temperature of cancer tissue.

As shown in FIG. 2, the applicator 20 is an antenna that is brought into close contact with a living body 32 and irradiates the living body 32 with radio waves to heat the target cancerous tissue. The applicator 20 is provided with a cooling mechanism 34 on the surface that comes into contact with the living body 32, as described above, in order to prevent skin burns due to heating due to dielectric loss in the skin portion. There is. This cooling mechanism 34 is provided with a vibrator 36 for passing water, which is used as a cooling liquid in this embodiment. In this cooling mechanism 34, the water cooled by the cooling device 21 is forcibly circulated by the pump 22 and passed through the cooling mechanism 34, thereby cooling the biological surface located on the opening surface of the applicator 20. It's becoming like that.

The temperature sensor 30 is a sensor for detecting the temperature of cancer tissue, and based on the information obtained here, the output of the magnetron 8 is adjusted by the first to fourth control functions. .

On the other hand, the main control section 18 further has a coolant exchange control function. In this main control section 18, when the information obtained by each of the sensors 12 and 30 is inputted via the A/D converters 16 and 42,
Input/output section 4 that receives this information and instructions from the operator
In addition to controlling the rotation speed of the pump 22 and the output of the magnetron 8 so that the temperature of the cancer tissue is maintained at a desired value based on the information from 4 (not shown),
In order to notify the operator of the heating state, the above-mentioned information is sent to the input/output section 44.

Next, the overall operation of the above device will be explained based on FIG. Here, the heating for the cancer tissue is set to 43.5 [°C].

Here, in this embodiment, as explained below, the first control function is an output decrease control function, the second control function is an output interruption control function, and the third control function is an output increase control function. As a function,
Further, the fourth control functions are configured to each act as a maximum level control function, and the coolant control function is configured to act as a coolant flow rate control function.

First, the cooling device 21 is operated (FIG. 3 50),
After the water has been sufficiently cooled, the rotation speed of the pump 22 is controlled by the coolant control function of the main control unit 18 (52 in the same figure). Thereafter, the operator determines the maximum output level of the magnetron 8 in advance according to the deep part of the cancer tissue, and sets this to the input/output section 44.
(54 in the same figure).

Here, the reason why the maximum output of the magnetron 8 is set to match the deep part of the cancer tissue is that if the microwave output is large, the temperature peak during heating will be near the surface, but if the output is small, the temperature peak will be near the surface. This is because the temperature gradually penetrates deeper and the temperature peak moves deeper.

Figure 4 shows the results of an experiment conducted on a phantom model that approximates a living body.
Temperature distribution (A) obtained when microwaves of [MHz] are irradiated based on a certain reference amount, and the irradiation of the micro liquid when the output is reduced by 3 [dB] from the reference amount in this case. A comparison with the obtained temperature distribution (B) is shown. This frequency band is the highest frequency range for heating therapy, and therefore the heating depth is limited to the superficial layer. nevertheless 3
[dB] Temperature distribution (B) with reduced output is approximately 0.25 [cm]
You can see that the temperature has reached its peak in the back. However, when the output is reduced, it takes a considerable amount of time to bring the cancer tissue to the desired temperature. FIG. 5 is an experimental example showing temperature changes in the heating section measured at regular intervals, and the curve represents the properties of the heating characteristic curve in this example.

On the other hand, setting of the maximum output during operation of the magnetron 8 is performed by a fourth control function in the main control section 18 based on information from the directional coupler 10. That is, from the difference in the power values of the incident wave and the reflected wave detected by the directional coupler 10, the output of the microwave that is effectively supplied to the applicator 20 is determined, and this output is sent to the operator via the input/output section 44. The maximum output of the magnetron 8 is set by adjusting it to the thus set value. In this case, the output may be set to a predetermined level using a phantom model in advance.

After the output of the magnetron 8 is set, microwave irradiation is performed for a certain period of time (Fig. 3, 56).
After that, turn off the output of magnetron 8 (see Figure 5).
8), then temperature measurement is started (60 in the same figure).

This temperature measurement is performed by a temperature sensor 30 for measuring the temperature of cancer tissue. The reason why microwave irradiation is not performed during temperature measurement is that the temperature sensor 30 inserted into the living body may be affected by the microwaves and errors may occur. Therefore, when using a temperature sensor that is less affected by microwaves, the above-described operation of "turning off the magnetron output" (step 58 in FIG. 3) is not necessary.

After the temperature is measured, it is determined whether the internal temperature of the heating location is higher than the internal temperature set value (43.5 [°C]) input by the operator (62 in the same figure).

Here, when the internal temperature is lower than the internal temperature set value input by the operator, the main control unit 18
Immediately, the third control function acts to give an instruction to the power control unit 14 to increase the output setting value of the magnetron 8 (64 in the same figure). However, in this case, the maximum input power set initially will not be exceeded. Then, when the next microwave irradiation time comes, the microwave irradiation is performed based on this set value. That is,
Microwave irradiation and measurement are repeated until the cancer tissue becomes higher than the set value, and this measurement time is used to increase the set value of the output of the magnetron 8 one step at a time, and for the next irradiation, the set value is set at the time of measurement. Microwave irradiation is performed by the generated output.

As a result, if the temperature of the cancerous tissue becomes higher than the internal set temperature, the second control function of the main control unit 18 acts to interrupt microwave irradiation until the temperature of the cancerous tissue falls below the set value, Repeat the temperature measurement loop. All such controls are performed by the main control section 18.

On the other hand, using this time, the control unit 4 activates the first control function to lower the output setting value of the magnetron 8 one step at a time (68 in the figure), and sets the output for the next irradiation.

By the way, the correlation between the heating time and the lethality of cancer tissue depends on the time it takes for the cancer tissue to reach a temperature around 43 degrees Celsius. Therefore, in this embodiment, the heating time is measured from the time when the temperature of the cancerous weaving exceeds the set value, and the heating is finished when the heating time entered in advance by the operator has arrived ( Figure 72).

FIG. 6 shows the relationship between the temperature state of the cancer tissue and the output state of the magnetron 8 during each microwave irradiation and measurement. In this figure, the intervals during which the temperature distribution is rising are during microwave irradiation, and the intervals during which the temperature distribution is falling are during temperature measurement. At the time of temperature measurement, the output of the magnetron 8 is zero.

Point B in the figure indicates the point at which the internal temperature exceeds the set temperature for the first time as a result of microwave irradiation using the maximum output of the magnetron 8, and measurement begins.
From here, the above-mentioned heating time starts. After that, measurement continues until the internal temperature falls below 43.5 [°C] (B and C in the figure), and during this time, the first control function in the main control section 18 is activated to control the magnetron 8. The output is controlled to drop by one step (FIG. 3, 68), thereby setting the next microwave to be irradiated. Therefore, the slope between CD and AB is lower. In addition, if the output setting value of the magnetron 8 was lowered too much during temperature measurement and the temperature did not reach 43.5 [℃] at the next irradiation (for example, EF in the figure), the flowchart in Figure 3. As shown in step 64 in FIG. 6, since the output is increased in the next measurement period (for example, FG in FIG. 6), the slope rises again (GH in the same figure). By repeating such control, temperature control with almost no ripples can be obtained.

Here, during the microwave irradiation time, initially 43.5
Even if it exceeds 43.5 [℃] at the point when it exceeds [℃], it will be 1.5
It is necessary to set the maximum output and irradiation time of the magnetron 8 so that the temperature does not rise above [°C].
This is because if the temperature rises by more than 1.5 degrees Celsius, it will exceed 45 degrees Celsius, which will have an adverse effect on normal cells.

As a method for determining this set value, for example, a setting method may be considered in which the temperature rise at the initial stage of microwave irradiation (OP in FIG. 6) is set to 3 [° C.] or less. This is because, as shown in Figure 5, the sound and rate of rise at each hour tend to increase in the early stages, and 43.5
This is based on the fact that the rate of increase is about 1/2 in the vicinity of [℃].

Figure 7 shows the cancer tissue temperature when the maximum output of the magnetron 8 is set low compared to Figure 6, and the start of heating is delayed compared to Figure 6. .

In addition, since it is sufficient to use a relatively low frequency to perform deep heating, an oscillator and a linear amplifier suitable for oscillating low-frequency microwaves were used instead of the magnetron 8 used in the above embodiment. May be used. In that case, the variable power is
Similar to controlling the magnetron, this is done by changing the oscillator power or the linear amplifier plate voltage using thyristor control. However, in this case, it is necessary to use an isolator to eliminate the influence of reflected waves.

〔Effect of the invention〕

Since the present invention is configured and functions as described above, it is possible to effectively perform heating treatment even for predetermined locations within a living body at different subsurface depths, and to prevent overheating. This can effectively suppress the generation of electromagnetic waves, and even if the temperature of the heated area drops and the electromagnetic waves are irradiated again, the output of the electromagnetic waves is automatically set and irradiation starts according to the degree of temperature drop. Therefore, it is possible to provide a hyperthermia heating device that is unprecedented and excellent in that it can alleviate heat transmission to the patient and effectively prevent damage to normal tissues.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing an example of an applicator,
FIG. 3 is a flowchart showing the operation of FIG. 1, and FIGS. 4 to 7 are diagrams showing the action and operation of the embodiment of FIG. 1, respectively. 8...Magnetron as a means of generating electromagnetic waves,
10...Directional coupler, 18...Main control unit equipped with output interruption control function, maximum output control function, output drop setting function, and output increase control function, 20...Applicator, 30...As temperature measuring means temperature sensor.

Claims (1)

[Scope of Claims] 1. In a hyperthermia heating device comprising an electromagnetic wave generating means that outputs electromagnetic waves and an applicator that irradiates a living body with the electromagnetic waves output from the electromagnetic wave generating means, the output of the electromagnetic wave generating means comprises: Correspondingly, a temperature measuring means is provided that detects the temperature of the heated area at regular intervals, and when this temperature measuring means detects a biological temperature that is higher than a preset temperature, the temperature measuring means detects the temperature of the heated area at a predetermined temperature. A main control section is equipped with an output interruption control function that interrupts and controls the output of the electromagnetic wave generating means, and this main control section further operates simultaneously with the output interruption control function to control the output of the electromagnetic wave generating means every time the temperature is measured by the temperature measuring means. , the output level of the electromagnetic wave generating means is set to 1.
A hyperthermia heating device characterized by having an output drop setting function that controls the drop in steps.