JPH0326982B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a hyperthermia device and sometimes microwaves to heat cancer tissue inside a living body with good heating distribution, thereby performing efficient cancer treatment. Regarding a hyperthermia device.

[Prior art] In recent years, cancer treatment in which malignant tumors are irradiated with microwaves has become well known.
This method takes advantage of the fact that cancer tissue becomes necrotic when heated at a temperature of 45°C for a certain period of time.

Hyperthermia devices used to treat such cancers emit microwaves by touching the applicator to the external skin surface of a living body, or inserting the applicator into organs such as the throat, esophagus, or uterus within the body cavity of the living body. The cancerous tissue is heated directly and from the surrounding area by the heating effect caused by the dielectric loss of the microwave in the in-vivo tissue.

In this manner, the hyperthermia device uses an applicator that contacts the surface of a living body or an applicator that is inserted into a body cavity to heat a desired site within a living body to effectively treat cancer.

[Problems to be Solved by the Invention] Problems of the Prior Art However, in conventional hyperthermia devices, the radiation pattern of the applicator depends on the micro frequency, and with only a single frequency, the heating distribution in the living body cannot be determined. There was a problem that it was not possible to make it uniform. This tendency is particularly strong in applicators for insertion into body cavities, and some kind of solution has been desired.

Therefore, the present inventor has proposed a device that uses a plurality of different microwaves to uniformize the heating distribution of the microwaves emitted from the applicator.
-1628), this will be explained based on FIGS. 3 to 5.

The hyperthermia device in this case uses an applicator for insertion into the body cavity, and the coaxial cable 1
A leaky coaxial portion 12 is formed at the tip of the coaxial cable 10, and this leaky coaxial portion 12 is composed of a center conductor 14 and an outer conductor 16 extending from the coaxial cable 10.
The outer conductor 16 is provided with a spiral slit 18. Note that the tip of the outer conductor 16 is short-circuited to the center conductor 14 .

Then, the microwave transmitted from the coaxial cable 10 leaks out little by little from the slit 18 of the outer conductor 16 in the leaky coaxial portion 12, and the microwave with the intensity distribution obtained in the entire leaky coaxial portion 12 is directed into the living body. It will be radiated.

The hyperthermia device shown in FIG. 3 supplies microwaves of two different frequencies f ₁ and f ₂ to the leakage coaxial section 12, and includes two microwave oscillators 20 and 22, and a coaxial switch. 24
Microwaves of two frequencies are alternately supplied to the leakage coaxial section 12 by switching control. Therefore, the heating distribution of the tissue within the body cavity in the leakage coaxial portion 12 is as follows:
As shown in FIG. 5, the heating distribution for frequency f ₁ (solid line 100) and the heating distribution for frequency f ₂ (dashed line 100') are superimposed, and as a result, the solid line 200 A uniform heating distribution as shown in is obtained.

Further, the hyperthermia device shown in FIG. 4 uses a sweep oscillator 26 to continuously supply a plurality of frequencies to the leakage coaxial section 12, and the wide-band frequency microwaves generated from the sweep oscillator 26 are transmitted to the wide-band amplifier. The intensity distribution formed by the continuously changing broadband frequency microwaves supplied to the leaky coaxial section 12 through 28 becomes uniform.

However, as is clear from the two hyperthermia devices mentioned above, the device for supplying multiple frequencies to the leakage coaxial section 12, the coaxial switch 24, the wideband amplifier 28, and the parts attached thereto in the above case, has a large number of components. Many of them had the disadvantage of being relatively expensive.

Further, since microwaves of a plurality of frequencies cannot be simultaneously supplied to the leakage coaxial section 12, the heating efficiency is still insufficient.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a hyperthermia device that can efficiently supply microwaves of multiple frequencies with a simple circuit configuration.

[Means for Solving the Problems] In order to achieve the above object, the hyperthermia device according to the present invention applies AM modulation to the fundamental frequency of microwaves and simultaneously supplies microwaves of multiple frequencies to an applicator. It is characterized by making the heating distribution uniform by doing so.

[Function] According to the above configuration, first, the frequency for AM modulation is set with respect to the fundamental frequency of the microwave determined by the shape and structure of the applicator itself, but this frequency depends on the application used. is selected as the unique frequency at which the intensity distribution is uniform in the data.

For example, if the fundamental frequency is F ₂ and the frequency for AM modulation is F ₁ , the leakage coaxial section will theoretically receive microwaves with frequencies F ₁ , F ₂ −F ₁ , F ₂ or F ₂ +F _1. Available.

Therefore, by selecting microwaves with optimal intensity distributions in these frequency ranges, it is possible to obtain a uniform heating distribution in the applicator radiation range.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a schematic configuration of a hyperthermia device using an applicator for insertion into a body cavity, and FIG. 2 shows a graph showing the radiation characteristics of microwaves in the applicator.

A characteristic feature of the present invention is that microwaves with AM modulation applied to the fundamental frequency are supplied to the applicator, and a microwave oscillator 30 that generates microwaves at the fundamental frequency is used.
and an AM modulator 32 as AM modulation means.

Here, the leakage coaxial portion 12 used in the example
The fundamental frequency of microwave _F2 is 2450MHz
If so, the leaky coaxial portion 12 has a reflection characteristic that varies depending on the frequency as shown in FIG. 2a. Therefore, AM modulation is performed in accordance with the frequency band where the amount of reflection is low as shown in the figure.

That is, the fundamental frequency of microwave F ₂ (2450M
Hz) and AM modulated at frequency F ₁ (350MHz), the AM modulator 30 outputs the frequency F ₁ −F ₂
(2100MHz) and F ₂ −F ₁ (2800MHz) [in this case F ₁
is ignored], and the microwave is output as shown in Fig. 2b.
The output state will be as shown in . In this case, in the reflection characteristics of the leaky coaxial portion 12, the frequency F ₂ +F ₁
Since the amount of reflection is small in the band , it does not contribute at all to the intensity distribution radiated from the leaky coaxial portion 12 .

Therefore, the leakage coaxial portion 12 in the embodiment emits micro-liquid in two frequency ranges, frequency F ₂ −F ₁ and frequency F ₂ , and the intensity distribution is determined by these two frequencies. It is possible to form a uniform heating distribution as shown in FIG. 5 described above. Since these two microwaves are simultaneously supplied to the leakage coaxial section 12, it is possible to radiate microwaves more efficiently than in conventional devices.

In this way, the microwave frequency is specified by the shape and structure of the applicator itself, and the frequency F ₁ for AM modulation is also specified by the characteristics of the applicator and the fundamental frequency F ₂ . Ru.
Therefore, if the fundamental frequency and the frequency for AM modulation are selected so that the peaks of high intensity are close to each other in the intensity distribution of the microwave emitted from the applicator, an extremely uniform intensity distribution can be obtained. becomes possible.

In the embodiment, a leaky coaxial applicator for insertion into a body cavity has been described, but the present invention is not limited to this, and the present invention can be similarly applied to hyperthermia devices using other applicators.

[Effects of the Invention] As explained above, according to the present invention, microwaves with AM modulation applied to the fundamental frequency are supplied to the applicator. can be supplied at the same time, and an efficient heating distribution in the radiation area can be obtained.

Further, according to the present invention, the circuit configuration for supplying multiple frequencies can be extremely simplified,
Manufacturing costs can be reduced and hyperthermia that is easy to manufacture can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an embodiment of a hyperthermia device according to the present invention, and Fig. 2 is a microwave reflection characteristic [a] in a leaky coaxial applicator.
and an explanatory diagram showing the intensity [b] of microwaves supplied to the applicator, Figures 3 and 4 are schematic configuration diagrams showing the conventional hyperthermia device, and Figure 5 is FIG. 3 is an explanatory diagram showing the intensity distribution of microwaves obtained by the hyperthermia device shown. 10...Coaxial cable, 12...Leaking coaxial part,
20, 22, 30...Microwave oscillator, 32...
...AM modulator.

Claims (1)

[Claims] 1 AM modulation that applies AM modulation to the fundamental frequency of the microwave in a hyperthermia device in which an applicator is placed in a treatment area and microwaves are supplied to the applicator to warm biological tissue. A hyperthermia device characterized by providing a means for simultaneously supplying microwaves of a plurality of frequencies to an applicator to make the heating distribution uniform. 2. The device according to claim 1, wherein the applicator is an applicator for insertion into a body cavity, which has a leakage coaxial portion in which a slit of a certain width is spirally formed in the outer conductor of a coaxial cable. Hyperthermia device.