JPS5957672A - Medical super-ultrasonic radiation multi-stage antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a medical pole R1 shortwave radiation multi-stage antenna, and more particularly to a medical ultrahigh-frequency radiation multi-stage antenna that can be applied to thermal treatment for tumors and the like.

In hyperthermia therapy, which uses the fact that cancer cells and the like are more sensitive to heat than normal cells to heat the affected area, ultrahigh-frequency radiation antezo is used to heat the affected area.

This type of extremely high frequency transmitting antenna is preferably as thin as possible in order to be used for treatment of intracavity, for example, the digestive system. Conventionally, a type of linear dipole antenna has been used. There is. In order to heat a wide affected area, a multi-stage antenna consisting of a plurality of dipole antennas arranged in a straight line has conventionally been used.

Shid-L et al., conventional medical ultrashort wave radiation multi-stage antenna 1
As shown in FIG. 1, the antenna is configured to feed power from the feed line 3 of one dipole antenna 2 to other dipole antennas 4 and 5 which are arranged in parallel to the antenna 2 via branch lines 6 and 7, etc. Therefore, under the conditions in which the antennas 3, 4.5 are applied to objects to be heated such as organ walls, the ultra high frequency oscillator 8
It was difficult to perform impedance matching. The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a multi-stage medical ultra-high frequency radiation antenna that can relatively easily increase the radiation efficiency of ultra-high frequency waves.

The purpose of this is to first convert the impedance into a real number by focusing on the fact that the impedance including the antenna and feed line becomes a real value when the length of the feed line (cable) is chosen appropriately, and then This is achieved by interconnecting each antenna with the oscillator. Next, the present invention will be explained using three dipole antennas 11 as linear antennas having the same shape.
, 12°13 as an example,
This will be explained in more detail based on FIG.

(1) First, depending on the oscillation frequency of the ultra-high frequency oscillator 15 (usually about 300 to 3,000 M■h), the antennas 11, 12, 13 are set so that the length is approximately three times the wavelength of the ultra-high frequency in body fluids. A pair of conductor parts 15°16,
, 17 , 18 , 19 , 20 are formed.

(2) The impedance ZA of each of the antennas 11, 12, and 13 in the living body is calculated.

(3) Next, connect the antennas 11, 12.
Connect cables 22, 23 and 24. Cable 22.23.
It is determined by the impedance including each of the 24 impedances. still,
Here, β is a constant determined by the wavelength, and d is the length of each cable 22, 23, 24. This cable 22,
23. Select the length d of each of 24 so that tan7#d=ω, and z1=7. o2/ZA.

However, when ZA is a complex number, there is a point where the imaginary part of Zl becomes zero and the real part takes an extreme value by appropriately selecting bn72d.

The antennas 11, 12, 13 with cables 22, 23, 24 having an impedance of f41 order K, Zl are appropriately combined in parallel or in series to have an impedance that is easy to combine with the oscillator 15.

In addition, for cables 22, 23, and 24 of the same length, connector 25
There is a misalignment in the position of the antennas 13 and 12 on the front side, and a large sag occurs in the cables 24 and 23, but since living bodies have a large dielectric constant, the length of each antenna 11, 12 and 13 is, for example, about 2 cIrL. This slack is, for example, about 2 to 'IcnL, and by appropriately bending the cables 24 and 23 near the connector 25, for example, this slack can be reduced to a level that poses no problem in practice.

(5) If necessary, matching with the oscillator may be achieved by using the cable 26 with an appropriate impedance and an appropriate length, again using the above equation (2).

(6) When actually manufacturing the multi-stage antenna 14, it is difficult to perform strictly accurate calculations, so the characteristics of the antenna 14 do not necessarily match the calculated values; however, according to the inventor's experience, the characteristics of the cable 26 By adjusting the length,
An antenna 14 having radiation characteristics within a practical range could be manufactured.

Examples will be described below.

Copper tape with a width of 11 mm is wrapped around a styrofoam pipe 21 with an outer diameter of 8 fins at 6 locations with an interval of 1 mm (15, 16, 17
, 18, 19, 20) Three sets of dipole antennas 11, 12, and 13 were constructed by setting two of each set as a set. Connect the power supply cables 22, 23, and 24 to each, and make the length of all three cables 148 cm, and connect the ends to the same connector 2.
5 and connected to a 915 MHz oscillator 15, the reflectance was 20%.

On the other hand, when the cables were cut with their tips aligned, the lengths of the cables were 146, 148, and 150 mm, and when they were bundled and connected to an oscillator, the reflectance was 60%.

Although an example of a multi-stage antenna consisting of three antennas has been described above, the number of antennas may be two, four or more. Also, above.

At connector 25, cable 22. An example has been described in which the antennas 11 and 12.13 with 3.24 are connected in parallel, but in some cases they may be connected in series, and in some cases they may be connected directly to the oscillator.

As described above, according to the present invention, a medical ultrahigh frequency radiation multi-stage antenna includes a plurality of linear antennas of the same shape arranged in a straight line, and each antenna has a linear antenna of the same length that is matched with the horizontal antenna. Since the antenna is formed by connecting feed lines, it can be relatively easily formed as a multi-stage antenna with high radiation efficiency.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional medical ultra-high frequency radiation multi-stage antenna, and FIG. 2 is an explanatory diagram of a medical extremely high-frequency radiation multi-stage antenna according to a preferred embodiment of the present invention. 11.12.13 Antenna. 21...pipe, 22,23.24...cable. Substitute (for bento players [1, Yoshio Figure 1 vB2 Figure] - Continued N113, tTh V!; Showa 573
November 29, 2, Title of the invention: 1% t~ultrahigh-frequency cutting multi-stage antenna 3, Relationship with the amendment J case 1:I11'F Applicant name: Title
(110) Kureha Chemical Industry Co., Ltd. 4, Agent
Yamada Building 5, 1-1-14 Shinjuku, Shinjuku-ku, Tokyo, ? i
Date of li positive order +1! + ru year month day 8,
Contents of the amendment (1) The official specification has been supplemented as shown in the attached sheet, but there is no change in the content). (2) Supplement the power of attorney as shown in the attached sheet. -yog

Claims (1)

[Claims] A medical ultrahigh frequency radiation multi-stage antenna consisting of a plurality of linear antennas of the same shape arranged in a straight line and each antenna connected to a feeder line of the same length.