JP4425454B2

JP4425454B2 - Microwave therapy device with electromagnetic shielding cover

Info

Publication number: JP4425454B2
Application number: JP2000359130A
Authority: JP
Inventors: 笹田雅昭
Original assignee: Minato Medical Science Co Ltd
Current assignee: Minato Medical Science Co Ltd
Priority date: 2000-11-27
Filing date: 2000-11-27
Publication date: 2010-03-03
Anticipated expiration: 2020-11-27
Also published as: JP2002159581A

Description

【０００１】
【産業上の利用分野】
本発明は、マイクロ波治療時に、電磁遮蔽カバーで放射アンテナごと患部を覆い、患部以外へのマイクロ波の放射を防止する電磁遮蔽カバーを有するマイクロ波治療器に関する。
【０００２】
【従来の技術】
現在、世界共通で定めたＩＳＭ−ｂａｎｄ（Industrial,Scientific,& Medical Application）として２４５０ＭＨｚのマイクロ波が割り当てられている。主要な利用例は、マイクロ波治療器、医療用ガンマー線照射装置、家庭用電子レンジ、オフィス内無線ＬＡＮ等である。
【０００３】
マイクロ波治療器による膝治療の様子を、図7に示す。図の71はマイクロ波放射アンテナで、72は膝である。アンテナを皮膚表面から少し離して患部に向け、マイクロ波を放射すると、マイクロ波が体内で吸収されて組織の温度が上昇し、温熱治療をおこなうことができる。治療が簡単で、しかも優れた温熱効果があるため、広く用いられている治療法である。
【０００４】
【発明が解決しようとする課題】
しかし、医療で使用するマイクロ波の出力は１００Ｗ以上と大きく、波長は比較的長いため、放射した電磁波は全てが患部に吸収されることはなく、患部以外にも放射され、弊害を及ぼすこともある。例えば図7の膝の治療ではアンテナの向きによって生殖器に、また、肩の治療では目に誤照射される可能性もある。また、周囲の妊婦等に照射される可能性もある。生殖器や目、妊婦等は治療の禁忌となっており、危険である。さらに、院内の各種電子機器に障害を与える可能性もある。このような問題に対処するため、マイクロ波治療エリアを電磁遮蔽カーテン等で囲ったり、電子機器を遮蔽したりしているが、問題は十分には解決されていないのが現状である。
【０００５】
【課題を解決するための手段】
そこで請求項１の発明では、マイクロ波照射アンテナ（12）を患部に向けてマイクロ波を照射して温熱治療をおこなうマイクロ波治療器に、
使用するマイクロ波に共振する素子をシート面に配列して反射面を構成した電磁遮蔽カバーで照射アンテナごと患部を覆って、マイクロ波が外部に漏れないようにする電磁遮蔽カバーを設けた。
請求項２では、請求項１記載の電磁遮蔽カバーを有するマイクロ波治療器の電磁遮蔽カバーを、使用するマイクロ波の共振を維持するに足りる厚さの低損失誘電体で覆い、電磁遮蔽カバーを生体に接触させても十分に遮蔽効果が出せるようにした。
請求項３の発明では、請求項１又は請求項２記載の電磁遮蔽カバーを有するマイクロ波治療器において、電磁遮蔽カバーの、放射電力密度の高いアンテナ近傍に導電体による電磁遮蔽体を併用するようにした。
【０００６】
【作用】
請求項１記載の発明により、電磁遮蔽カバーで照射アンテナごと患部を覆っているため、照射アンテナから電磁遮蔽カバーにマイクロ波が放射されると、前記電磁遮蔽カバーに配列した素子が共振し、逆位相の電磁波を発生し、入射エネルギーは反射波として反射されるため、電磁波が外部に漏れないように遮蔽することができる。
請求項２記載の発明により、電磁遮蔽カバーは、請求項１記載のカバー両面を十分な厚さの低損失誘電体で覆ったので、生体に直接接触してカバーする場合も、電磁波を十分に遮蔽できる。
請求項３記載の発明により、電磁遮蔽カバーは、放射アンテナの近傍に導電体による電磁遮蔽を施しているので、アンテナ近傍の強い電磁波も十分に遮蔽できる。
【０００７】
【実施例】
本発明の電磁遮蔽カバーの原理を図1に、請求項1と請求項２記載の電磁遮蔽カバーの実施例をそれぞれ図2（a）と（b）に示す。
図1に示すように、入射電磁波１が例えば入射電磁波の半波長の長さの理想導体棒４に入射すると、導体棒４は共振により逆位相の電磁波を発生するので、入射エネルギーは反射波２として反射される。この場合、導体棒４の周囲に等価な反射面、実際には回転楕円体に近い遮蔽面３を発生する。このような共振導体棒を配列した反射面は、ＦＳＳ（Frequency Selective Surface）として知られている。
【０００８】
請求項１記載の発明はＦＳＳをマイクロ波治療に応用するもので、使用する電磁遮蔽カバーの実施例を図2（a）に示す。導体棒の長さは使用するマイクロ波の１／２波長であり、この実施例では、任意の偏波面の電磁波を反射するようにＹ字状にした。図2（ａ）は、この共振素子４を、合成樹脂フィルム面１３に印刷配列したものであり、共振周波数の電磁波を反射させることができる。図1で、導体棒４のなす等価反射面の面積Ａeffは次式で表される。
【数１】
Ａeff≒０．１３λ
ここでλは電磁波の波長である。
共振素子４は、この式を勘案し、電磁遮蔽カバーが使用するマイクロ波に対して遮蔽効果を出せるように設計する。
ここでは共振素子４を合成樹脂フィルムに印刷した例を示したが、共振素子を配列するシートの材質や配列法は問わない。
【０００９】
しかし、ＦＳＳ素子が共振機能を維持するには、理論的に１／１０波長以上の間隔が必要である。図2（ａ）のフィルムを生体に密着させて用いると、フィルムと生体間に空間が無くなり、電磁遮蔽効果が低下する。そこで請求項２記載の発明では、図2（ｂ）に示すように、この共振を維持するに足りる厚さの低損失誘電体５で覆って共振面機能を維持し、電磁波を反射させるようにした。具体的には低損失材５として、厚さ１５ｍｍの発砲ウレタン等を使用した。なお、この実施例では、取り扱いの利便性と清潔さの維持のため、布製のカバー６で覆っている。
【００１０】
図3は、図2（ｂ）の電磁遮蔽カバーを用いてベッド上で治療をおこなう場合の模式図を示す、請求項2記載の発明の実施例である。図3の７は電磁遮蔽カバー、８はベッドのフレーム、１１はマットである。ベッド上の患者９の患部に放射アンテナ１２を向け、電磁遮蔽カバー7でアンテナごと患部を覆っている。この図では、アンテナと生体が接しているようにみえるが、実際の治療では、図7のように、非接触で照射する。マット１１を電波吸収材にすると、さらに遮蔽効果が向上する。
図4は、患部９にアンテナ１２をセットした後、患部をアンテナの上から電磁遮蔽カバー７で覆って治療する例を示している。図3のようにベッドを用いると、ベッドのフレーム８やマット１１の材質によって遮蔽効果が低下することもあるが、図4のように全体をカバー７で覆ってしまうと、効果的な電磁遮蔽ができる。
【００１１】
図5は、図3の実施例における遮蔽効果の実測値である。ベッドから１ｍの距離の電界強度を測定し、遮蔽度の低い順に整理した分布度を示す。遮蔽度は、カバー７がある場合と無い場合の比をとって、対数表示した。図中の負荷とは人体のことで、吸収とはベッドマット１１に電磁波吸収体を使用したということである。本発明のカバーは、少なくとも３０ｄＢ、ベッドのマット部１１に吸収体を入れれば５０ｄＢ以上の遮蔽が可能であり、マイクロ波治療時の各種電波障害を解決することができる。ｃｌｏｓｅの意味は、図3のように、生体をベッドと電磁遮蔽カバーで覆ったという意味である。
【００１２】
以上のように、本発明の電磁遮蔽カバーは数十ｄＢの電磁遮蔽効果を有するが、入射電磁波が強いと、電磁遮蔽カバーを透過する電磁波も強くなり、各種の電磁障害を与える。つまり、図3や図4のようにして治療をおこなうと、アンテナからは強い電磁波を放射するので、アンテナ近傍で電磁遮蔽カバー7から電磁波が漏洩する。これを解決するために、請求項３の発明では、請求項１又は２記載の電磁遮蔽カバーのアンテナ近傍に導電体による電磁遮蔽体を設け、電磁遮蔽効果を向上させた。これを用いた治療の模式図を図6に示す。図の８はベッドフレーム、１１はマット、９は患者、１２は放射アンテナ、７は請求項２記載の電磁遮蔽カバー、１４は電磁遮蔽効果を高めるための導電体の電磁遮蔽体である。電磁遮蔽体１４は電磁遮蔽カバー７に塗布その他の手段で薄膜形成すると使いやすい。しかし、電磁遮蔽カバー７と導電体１４とを組み合わせて使用するものであればよい。
【００１３】
【発明の効果】
本発明のマイクロ波治療器で使用する電磁遮蔽カバーは、マイクロ波治療器のアンテナから照射するマイクロ波を選択的に、かつ効果的に遮蔽する。また、共振素子をＹ字状にしたので、電磁波がどのように偏向していても対応できる。本発明のマイクロ波治療器で使用する電磁遮蔽カバーの電磁遮蔽効果は少なくとも３０ｄＢはあるので、目や生殖器、妊婦等への誤照射の可能性が低くなり、マイクロ波治療の安全性が高くなる。また、他の電子機器等への障害が少なくなるので、他の医療機器や電子機器への影響が少なくなり、安全性が高くなり、電磁障害に伴う保守の手間やコストを低減できる。また、従来の電磁遮蔽は大掛かりな工事が必要であったし高価であったが、本発明の電磁遮蔽カバーを用いると、安価で、確実な遮蔽が手軽に可能になる。
【００１４】
【図面の簡単な説明】
【図1】本発明のマイクロ波治療器で使用する電磁遮蔽カバーの原理図である。
【図2】（ａ）は請求項１の、（ｂ）は請求項２の、電磁遮蔽カバーの実施例である。
【図3】本発明の使用法を示す模式図である。
【図4】本発明の別の使用法を示す模式図である。
【図5】本発明で使用する電磁遮蔽カバーの遮蔽効果の実測データである。
【図6】請求項３記載の発明の電磁遮蔽カバーの使用法を示す模式図である。
【図7】従来のマイクロ波治療器による膝治療の様子を示す図である。
【符号の説明】
１・・・入射波２・・・反射波
３・・・等価反射面４・・・導体棒
５・・・低損失誘電体６・・・布カバー
７・・・本発明の電磁遮蔽カバー８・・・ベッドフレーム
９・・・患者（患部）１１・・ベッドのマット
１２・・マイクロ波放射アンテナ１３・・導体棒を配列したシート
１４・・電磁波反射用導電体７１・・マイクロ波放射アンテナ
７２・・膝[0001]
[Industrial application fields]
The present invention relates to a microwave treatment device having an electromagnetic shielding cover that covers an affected part together with a radiation antenna with an electromagnetic shielding cover during microwave therapy, and prevents microwave radiation to other than the affected part .
[0002]
[Prior art]
Currently, a microwave of 2450 MHz is allocated as an ISM-band (Industrial, Scientific, & Medical Application) defined in common throughout the world. Major applications are microwave therapy devices, medical gamma ray irradiation devices, home microwave ovens, office wireless LANs, and the like.
[0003]
Fig. 7 shows the knee treatment using a microwave treatment device. In the figure, 71 is a microwave radiation antenna, and 72 is a knee. When the antenna is directed slightly away from the skin surface and directed to the affected area, and microwaves are emitted, the microwaves are absorbed in the body, the temperature of the tissue rises, and thermotherapy can be performed. It is a widely used treatment because it is easy to treat and has excellent thermal effects.
[0004]
[Problems to be solved by the invention]
However, because the microwave output used in medical treatment is as large as 100W or more and the wavelength is relatively long, all the radiated electromagnetic waves are not absorbed by the affected area, but are also emitted outside the affected area and may cause harmful effects. is there. For example, in the knee treatment shown in FIG. 7, the genitalia may be misirradiated depending on the antenna orientation, and in the shoulder treatment, the eye may be erroneously irradiated. Moreover, there is a possibility of irradiation to surrounding pregnant women. Genital organs, eyes, pregnant women, etc. are contraindicated for treatment and are dangerous. Furthermore, there is a possibility that various electronic devices in the hospital may be damaged. In order to deal with such a problem, the microwave treatment area is surrounded by an electromagnetic shielding curtain or the like, or an electronic device is shielded, but the problem is not sufficiently solved.
[0005]
[Means for Solving the Problems]
Therefore, in the invention of claim 1, a microwave treatment device for performing a thermal treatment by irradiating a microwave with the microwave irradiation antenna (12) toward the affected part,
An electromagnetic shielding cover that covers the affected area together with the irradiation antenna is covered with an electromagnetic shielding cover in which elements that resonate with the microwave to be used are arranged on the sheet surface to form a reflecting surface, so that the microwave does not leak outside .
In claim 2, the electromagnetic shielding cover of the microwave therapy device having the electromagnetic shielding cover according to claim 1 is covered with a low-loss dielectric having a thickness sufficient to maintain the resonance of the microwave used , and the electromagnetic shielding cover is covered. A sufficient shielding effect can be obtained even if it is brought into contact with a living body.
According to a third aspect of the present invention, in the microwave treatment device having the electromagnetic shielding cover according to the first or second aspect , an electromagnetic shielding body made of a conductor is used in the vicinity of the antenna having a high radiation power density of the electromagnetic shielding cover. I did it.
[0006]
[Action]
According to the first aspect of the present invention , since the affected part is covered with the irradiation antenna by the electromagnetic shielding cover, when the microwave is radiated from the irradiation antenna to the electromagnetic shielding cover, the elements arranged in the electromagnetic shielding cover resonate and reversely A phase electromagnetic wave is generated, and incident energy is reflected as a reflected wave, so that the electromagnetic wave can be shielded from leaking outside .
According to the invention described in claim 2 , since the electromagnetic shielding cover covers both surfaces of the cover according to claim 1 with a low-loss dielectric having a sufficient thickness, even when the cover is in direct contact with a living body , the electromagnetic shielding is sufficiently performed. Can be shielded.
According to the invention described in claim 3 , since the electromagnetic shielding cover is provided with electromagnetic shielding by a conductor in the vicinity of the radiation antenna, it can sufficiently shield strong electromagnetic waves in the vicinity of the antenna.
[0007]
【Example】
1 the principle of electromagnetic shielding cover of the present invention, illustrating an embodiment of an electromagnetic shielding cover according to claim 2 wherein the claim 1 in FIGS 2 and (a) (b).
As shown in FIG. 1, when the incident electromagnetic wave 1 is incident on an ideal conductor rod 4 having a length of half the wavelength of the incident electromagnetic wave, for example, the conductor rod 4 generates an electromagnetic wave having an opposite phase due to resonance. As reflected. In this case, an equivalent reflecting surface around the conductor rod 4, actually a shielding surface 3 close to a spheroid is generated. A reflective surface on which such resonant conductor rods are arranged is known as FSS (Frequency Selective Surface).
[0008]
The invention described in claim 1 applies FSS to microwave therapy, and an example of an electromagnetic shielding cover to be used is shown in FIG. The length of the conductor rod is ½ wavelength of the microwave to be used. In this embodiment , the conductor rod is Y-shaped so as to reflect electromagnetic waves having an arbitrary polarization plane. FIG. 2A shows the resonance element 4 printed and arranged on the synthetic resin film surface 13, and can reflect electromagnetic waves having a resonance frequency. In FIG. 1, the area Aeff of the equivalent reflecting surface formed by the conductor rod 4 is expressed by the following equation.
[Expression 1]
Aeff ≒ 0.13λ
Here, λ is the wavelength of the electromagnetic wave.
Resonant element 4, in consideration of this equation is designed to put out the shielding effect against microwaves used electromagnetic shielding cover.
Here, an example in which the resonance element 4 is printed on a synthetic resin film is shown, but the material and arrangement method of the sheet on which the resonance elements are arranged are not limited.
[0009]
However, in order for the FSS element to maintain the resonance function, theoretically, an interval of 1/10 wavelength or more is necessary. If Figure 2 the film (a) is brought into close contact to the living body are use, there is no space between the film and the biological, electromagnetic shielding effect is reduced. Therefore, in the invention described in claim 2, as shown in FIG. 2 (b), the resonance surface function is maintained by covering with a low-loss dielectric 5 having a thickness sufficient to maintain the resonance, and the electromagnetic wave is reflected. did. Specifically, a foamed urethane having a thickness of 15 mm was used as the low-loss material 5. In this embodiment, it is covered with a cloth cover 6 for the convenience of handling and the maintenance of cleanliness.
[0010]
FIG. 3 is an embodiment of the invention according to claim 2 showing a schematic diagram when treatment is performed on a bed using the electromagnetic shielding cover of FIG. 2B . In FIG. 3, 7 is an electromagnetic shielding cover , 8 is a bed frame, and 11 is a mat. The radiation antenna 12 is directed toward the affected part of the patient 9 on the bed, and the affected part is covered with the electromagnetic shielding cover 7 together with the antenna. In this figure, the antenna appears to be in contact with the living body, but in actual treatment, irradiation is performed in a non-contact manner as shown in FIG . When the mat 11 is a radio wave absorber, the shielding effect is further improved.
FIG. 4 shows an example in which after the antenna 12 is set on the affected part 9, the affected part is covered with an electromagnetic shielding cover 7 from above the antenna to be treated. When the bed is used as shown in FIG. 3, the shielding effect may be lowered depending on the material of the bed frame 8 and the mat 11, but if the whole is covered with the cover 7 as shown in FIG. Can do.
[0011]
FIG. 5 shows measured values of the shielding effect in the embodiment of FIG. The electric field intensity at a distance of 1 m from the bed is measured, and the distribution degree is arranged in ascending order of shielding degree. The degree of shielding was expressed in logarithm by taking the ratio between the case with and without the cover 7. The load in the figure is a human body, and the absorption means that an electromagnetic wave absorber is used for the bed mat 11. The cover of the present invention is capable of shielding at least 30 dB and 50 dB or more if an absorber is placed in the mat portion 11 of the bed, and can solve various radio wave interferences during microwave treatment. The meaning of “close” means that the living body is covered with a bed and an electromagnetic shielding cover as shown in FIG.
[0012]
As described above, the electromagnetic shielding cover of the present invention has an electromagnetic shielding effect of several tens of dB. However, if the incident electromagnetic wave is strong, the electromagnetic wave transmitted through the electromagnetic shielding cover is also strong, which causes various electromagnetic interferences. That is, when treatment is performed as shown in FIGS. 3 and 4, strong electromagnetic waves are radiated from the antenna, and electromagnetic waves leak from the electromagnetic shielding cover 7 in the vicinity of the antenna. In order to solve this, in the invention of claim 3, an electromagnetic shielding body made of a conductor is provided in the vicinity of the antenna of the electromagnetic shielding cover of claim 1 or 2 to improve the electromagnetic shielding effect. A schematic diagram of treatment using this is shown in FIG. In the figure, 8 is a bed frame, 11 is a mat, 9 is a patient, 12 is a radiating antenna, 7 is an electromagnetic shielding cover according to claim 2, and 14 is an electromagnetic shielding body of a conductor for enhancing the electromagnetic shielding effect. The electromagnetic shield 14 is easy to use if a thin film is formed on the electromagnetic shield cover 7 by coating or other means. However, any combination of the electromagnetic shielding cover 7 and the conductor 14 may be used.
[0013]
【The invention's effect】
The electromagnetic shielding cover used in the microwave therapy device of the present invention selectively and effectively shields the microwave irradiated from the antenna of the microwave therapy device . Further, since the resonant element is Y-shaped, it can cope with how the electromagnetic waves are deflected. Since the electromagnetic shielding effect of the electromagnetic shielding cover used in the microwave treatment device of the present invention is at least 30 dB, the possibility of erroneous irradiation to eyes, genital organs, pregnant women, etc. is reduced, and the safety of microwave treatment is enhanced. . In addition, since the obstacles to other electronic devices and the like are reduced, the influence on other medical devices and electronic devices is reduced, the safety is improved, and the maintenance effort and costs associated with electromagnetic interference can be reduced. Further, the conventional electromagnetic shielding requires large-scale construction and is expensive. However, when the electromagnetic shielding cover of the present invention is used, it is cheap and reliable shielding can be easily performed.
[0014]
[Brief description of the drawings]
FIG. 1 is a principle view of an electromagnetic shielding cover used in a microwave therapy device of the present invention.
2A is an embodiment of an electromagnetic shielding cover according to claim 1 and FIG.
FIG. 3 is a schematic diagram showing how to use the present invention.
FIG. 4 is a schematic view showing another usage of the present invention.
FIG. 5 is actual measurement data of a shielding effect of an electromagnetic shielding cover used in the present invention.
FIG. 6 is a schematic view showing how to use the electromagnetic shielding cover of the invention according to claim 3;
FIG. 7 is a view showing a state of knee treatment by a conventional microwave treatment device .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Incident wave 2 ... Reflected wave 3 ... Equivalent reflective surface 4 ... Conductor bar 5 ... Low loss dielectric 6 ... Cloth cover 7 ... Electromagnetic shielding cover 8 of this invention ... Bed frame 9 ... Patient (affected part) 11 ... Bed mat 12 ... Microwave radiation antenna 13 ... Sheet 14 with conductor rods arranged ... Conductor for electromagnetic wave reflection 71 ... Microwave radiation antenna 72 ... Knee

Claims

A microwave therapy device that performs thermotherapy by irradiating the irradiation antenna (12) toward the affected area and irradiating microwaves ,
Element resonates with the microwave to be used (4) a micro brewing covering the affected area by irradiating antennas seat surface (13) in sequence to configure the conductive magnetic shield covers the reflecting surface for reflecting the microwave (7) characterized in that the waves provided an electromagnetic shielding cover (7) for shielding to prevent leakage to the outside, a microwave treatment apparatus having a conductive magnetic shielding cover.

The electromagnetic shielding cover (7) for microwave treatment according to claim 1, wherein the microwave shielding cover (7) is covered with a low-loss dielectric (5) having a thickness sufficient to maintain the resonance of the microwave used . Microwave therapy apparatus having according to claim 1, the conductive magnetic shielding cover.

The microwave treatment having an electromagnetic shielding cover according to claim 1 or 2, wherein an electromagnetic shielding body (14) made of a conductor is provided in the vicinity of the irradiation antenna of the electromagnetic shielding cover (7). Vessel .