JPH0463710B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device that heats a local area within a conductive object by electromagnetic induction, and more specifically, the present invention relates to a device that heats a local area within a conductive object by electromagnetic induction. The present invention relates to a device suitable for heat treating cancer.

[Conventional technology]

Cancer cells and tumors are more sensitive to heat than normal tissues. Research on hyperthermia, a cancer treatment method that utilizes this feature, has been attracting attention in recent years. This reduces the temperature of the lesion to 42°C to 45°C.
The aim is to increase the level of cancer cells to cause necrosis or to prevent their proliferation.

[Problem that the invention seeks to solve]

However, because it is extremely difficult to concentrate the heat spot only on the lesion, this ipathermia technology has not yet been put into practical use. That is, until now, when there are foci deep within the composition, it has been difficult to form hot spots only there.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a local heating device within a conductive object that can be applied to heat treatment of cancer, or to other medical and industrial applications.

[Means for solving problems]

To achieve the above object, the present invention is a device for heating a local area within a conductive object, which comprises a plurality of high-frequency alternating magnetic field generating devices provided corresponding to a plurality of virtual straight lines passing through the local area, The high frequency alternating magnetic field generator is configured to generate a high frequency alternating magnetic field for causing an eddy current to flow within the object,
Further, the high frequency alternating magnetic field generator has a first magnetic pole of the first polarity, a second magnetic pole of the second polarity, a third magnetic pole of the first polarity, and a fourth magnetic pole of the second polarity. a magnetic pole, a fifth magnetic pole of the first polarity, a sixth magnetic pole of the second polarity, a seventh magnetic pole of the second polarity, and a first magnetic pole.
and an eighth magnetic pole with a polarity of , the first magnetic pole is arranged along the straight line on one side of the object, and the second magnetic pole is arranged on the other side of the object with The third magnetic pole is arranged along a straight line and is arranged opposite to the first magnetic pole to generate a first high-frequency alternating magnetic field between the third magnetic pole and the third magnetic pole on the other side of the object. The fourth magnetic pole is arranged along the straight line on one side of the object and generates a second high-frequency alternating magnetic field between it and the third magnetic pole. The fifth and sixth magnetic poles are arranged opposite to the third magnetic pole for
The magnetic pole is disposed between the first magnetic pole and the fourth magnetic pole and is set to generate a high frequency alternating magnetic field for limiting the spread of the first and second high frequency alternating magnetic fields, Seventh and eighth magnetic poles are disposed between the second magnetic pole and the third magnetic pole, and are configured to generate a high frequency alternating magnetic field for limiting the spread of the first and second high frequency alternating magnetic fields. and is configured to heat the local area corresponding to the intersection of the plurality of virtual straight lines by sequentially operating the plurality of high frequency alternating magnetic field generators. This relates to local heating devices.

In the device of the present invention, the spread of the first and second high-frequency alternating magnetic fields is suppressed by the effects of the fifth, sixth, seventh, and eighth magnetic poles, making it possible to heat a minute portion.

〔Example〕

Next, a method and apparatus for heating a lesion in a human body according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show, in a simplified manner, an apparatus for thermally treating a cancerous lesion 2 in a human body 1, for example the head. The cancer focus 2 is located at the center of the human body 1, which is shown in a cylindrical shape. When heating this lesion area 2, a plurality of virtual straight lines 3, 4, 5, 6 passing through this area are set, and each straight line 3, 4,
5, 6 along four magnetic field generators 7, 8, 9,
Place 10.

Now, to explain one magnetic field generator 7 as an example, the first, second, third and fourth coils 11,
12, 13, and 14, to which a high frequency AC power source 15 is connected via a switch _S1 . 1st
The second coil 11 is placed on one side of the human body 1 along the straight line 3, and the second coil 12 is placed on the other side of the human body 1 along the straight line 3. The third coil 13 is placed on the other side of the human body 1 along the straight line 3, and the fourth coil 14 is placed on the other side of the human body 1 along the straight line 3.
is placed on one side of the first coil 11
and the fourth coil 14, and the second coil 12 and the third coil 13 are arranged in parallel with an interval determined according to the size of the cancerous lesion 2. First, second, third and fourth coils 11, 1
2, 13, and 14 are sequentially connected in series so as to have a first polarity, a second polarity, a first polarity, and a second polarity based on the direction toward the human body 1. When a high frequency current of, for example, 10 ⁵ or more is applied to these coils 11 to 14 by the power supply 15 via the switch S ₁ , at a certain instant a first high frequency alternating magnetic field as shown by the arrow 16 and a first high frequency alternating magnetic field as shown by the arrow 17 are generated. Second
A high frequency alternating magnetic field is generated. At this time, the first magnetic pole generated on the human body side of the first coil 11 becomes the north pole, the second magnetic pole generated on the human body side of the second coil 12 becomes the south pole, and the third magnetic pole generated on the human body side of the third coil 13 becomes the north pole. The resulting third magnetic pole becomes the N pole, and the fourth coil 1
The fourth magnetic pole generated on the human body side of No. 4 is the S pole.

The centers of the first and second high-frequency alternating magnetic fields 16 and 17 are along the virtual straight line 3 but do not coincide, and extend so as to sandwich the lesion 2 . The first high-frequency alternating magnetic field 16 and the second high-frequency alternating magnetic field 17 have a phase difference of 180 degrees, that is, have an antiphase relationship. Therefore, the first and second high frequency alternating magnetic fields 1
The eddy current in the columnar part sandwiched between 6 and 17 is stronger than in other parts. Note that since the human body and the cancerous lesion 2 are electrically conductive, eddy currents are generated by electromagnetic induction based on the high-frequency magnetic field. When eddy currents are generated as described above, Joule heat is generated and the temperature rises.

What is important here is that the magnitude of the high-frequency current and the coils 11 to 14 should be adjusted so that normal parts of the human body 1 will not be destroyed due to temperature rise caused by a single magnetic field generator 7.
The first step is to determine the number of turns. Therefore, a single magnetic field generator 7 can reach the required temperature (42
It is difficult to raise the temperature to 45°C. Therefore, high-frequency alternating magnetic fields are also generated by magnetic field generators 8, 9, and 10 on other straight lines 4, 5, and 6 that intersect the lesion 2. As a result, the temperature of the intersection region of each high-frequency alternating magnetic field, that is, the temperature of the escape nest portion 2 can be made significantly higher than that of the other regions.

18, 19, 20, and 21 are fifth, sixth, seventh, and eighth coils, which are provided to limit the spread of the first and second high-frequency alternating magnetic fields 16, 17. Although wiring is omitted in FIG. 1, specifically, as shown in FIG. 3, the coils are connected to the same power source 15 as the first to fourth coils 11 to 14. The fifth, sixth, seventh, and eighth coils 18, 19, 20, and 21 have a first polarity, a second polarity, a second polarity, and a third polarity based on the side facing the human body 1. Connect each coil 18 to 21 so that the polarity is
The polarity of is determined. Therefore, at a certain moment, as shown in FIG. 3, the fifth, sixth, seventh and eighth coils 18, 19, 20, 21 have N poles
It becomes S pole, S pole, N pole. The strength of the magnetic poles of the fifth to eighth coils 18 to 21 is set so as to limit the spread of the first and second high frequency alternating magnetic fields 16 and 17. That is, the first magnetic pole P ₁ and the fourth
In order to limit the flow of magnetic flux between the two magnetic poles _P4 when they approach each other, repulsion between the first magnetic pole _P1 and the fifth magnetic pole _P5 , which are adjacent to each other and have the same polarity, and The repulsion between the fourth magnetic pole P ₄ and the sixth magnetic pole P ₆ is utilized. The seventh and eighth magnetic poles P ₇ and P ₈ on the right are also utilized in the same way. Note that the strengths of the fifth and sixth magnetic poles P ₅ and P ₆ are set so that a flow of magnetic flux occurs between them. The strengths of the seventh and eighth magnetic poles P ₇ and P ₈ are similarly set.

In FIG. 1, the second magnetic field generator 8 is arranged at an angular position perpendicular to the first magnetic field generator 7, and the first to eighth coils 11, 12 of the first magnetic field generator 7 ,13,14,18,19,2
0, 21, the 9th to 16th coils 11
a, 12a 13a, 14a, 18a, 19a, 2
It has 0a and 21a. This second magnetic field generator 8 generates first and second high frequency alternating magnetic fields 16, 17.
Except for generating third and fourth high-frequency alternating magnetic fields 16a and 17a in a direction perpendicular to the first
This is the same as the magnetic field generating device 7 of . Therefore, detailed explanation thereof will be omitted.

The third and fourth magnetic field generators 9 and 10 are
and second magnetic field generators 7 and 8. In order to intensify the three-dimensional heating of the lesion 2, third and fourth magnetic field generators 9 and 10 are installed.
The coils are arranged in parallel in the vertical axis (Z-axis) direction. Therefore, only the upper coil is shown in FIG. FIG. 2 shows the relationship between the third magnetic field generator 9 and the human body 1 as seen from the - line in FIG. The 17th to 20th coils 1 correspond to the first, second, third, and fourth coils 11 to 14 and the fifth to eighth coils 18 to 21 of the first magnetic field generator 7.
1b, 12b, 13b, 14b and 21st to 24th coils 18b, 19b, 20b, 21b are provided, respectively. As a result, arrows 16a and 17a
As shown in FIG. 2, fifth and sixth high frequency alternating magnetic fields are generated. The configuration and operation of the third magnetic field generator 9 are the same as the first magnetic field generator 7 except that the fifth and sixth high frequency alternating magnetic fields 16b, 17b are generated at different angles. Coil 11 in Figure 1
The fourth magnetic field generating device 10, indicated only by c and 12c, is also configured essentially the same as the first magnetic field generating device 7.

When heating the cancer lesion 2 with the apparatus shown in FIGS. 1 to 3, by switching the first to third switches S ₁ , S ₂ , S ₃ and a fourth switch (not shown), A high frequency current is sequentially applied to the first to fourth magnetic field generators 7 to 10 with a time difference. As a result, an eddy current is generated due to electromagnetic induction, and the cancer focus portion 2 is heated by Joule heat. At this time, no matter which of the first to fourth magnetic field generators 7 to 10 is supplied with current, an eddy current flows through the cancer focus area 2, so that the temperature of the cancer focus area 2 becomes the highest. At this time, cancer focus area 2
In addition, eddy currents flow and the temperature rises, but since the heating caused by the eddy currents is not superimposed, the temperature does not become very high. Note that the heating area is the cancer lesion area 2.
If it protrudes significantly from the surface, the surrounding area may be cooled.

If the frequency of the high-frequency alternating magnetic field is increased, the heat generation effect due to eddy currents will also increase. At this time, it is thought that eddy currents concentrate near the conductor surface due to the skin effect. That is, when a lesion is located deep within the human body, applying a high frequency magnetic field may fail to form a hot spot at the lesion. However, at frequencies below 100MHz, the skin effect can be almost ignored.

The cooling effect of blood flow is a factor that prevents temperature rise in the body, but ignoring this, the time required to raise the temperature of the lesion at a depth of 0.05 m from the epidermis by 5°C is calculated as Magnetic field B ₀ = 1 mT, specific heat C = 4.19×10 ³ J・K ^-1・g ^-1 , density D = 1.01 gcm
^-3 , it is approximately 770ms when calculated under the condition of a frequency of 50MHz. Therefore, even though there is a cooling effect due to blood flow,
Hot spot formation is fully possible. In addition, if the location of the lesion and the medical condition permit, temporary hemostasis can be achieved, and laser beams, hot water, etc. can be used in combination.

As is clear from the above, this treatment method does not use radiation or drugs, so there are very few side effects. Therefore, great effects can be expected for cancer heating treatment inside the human body, which cannot be treated with lasers or microwaves.

Next, the fact that the eddy current density in the region sandwiched between the first high-frequency alternating magnetic field 16 and the second high-frequency alternating magnetic field 17 becomes large will be explained with reference to FIGS. 4 to 6. FIGS. 4 and 5 show a method of increasing the current density near the center x=y=0 of a square conductor plate 22 with scales of ±8 in the x-axis and y-axis directions. A two-dimensional conductor plate having uniform conductivity and magnetic permeability is prepared as the conductor plate 22, and a uniform magnetic field H ₀ is applied to the entire conductor plate. In addition, there is a uniform magnetic field in the two small areas 23 and 24 indicated by diagonal lines in FIGS. 4 and 5.
In addition to H ₀ , local magnetic fields H _A and H _B are applied in the directions of the arrows in FIG. 5, respectively. That is, on the one hand
A local magnetic field H _A having the same phase as H ₀ is applied to the other, and a local magnetic field H _B having the opposite phase to H ₀ is applied to the other. This local magnetic field H _A ,
To generate H _B , for example, air-core coils (not shown) are placed above and below the conductor plate 22 and used as a pair. FIG. 6 shows the result of calculating the eddy current density on the y-axis of the two-dimensional conductor plate 22 shown in FIG. Here, the local magnetic fields H _A , H _B are |H _A |=
|H _B |=a|H ₀ |, calculate the eddy current density for a=1 and a=10, and use the characteristic line 25 to find a=
The results are shown for the case of 10, and a=1 according to the characteristic line 26.
The results are shown for the case. As is clear from Fig. 6, when the amplitudes of the local magnetic fields H _A and H _B are small (i.e. a=
In 1), the influence of local magnetic fields H _A and H _B is small, and the current density near the center y = 0 does not increase, but the local magnetic fields
It can be seen that when the amplitudes of H _A and H _B are large (ie, a=10), the influence of the local magnetic field is large, and two current loops gather near the center y=0, making it possible to obtain a large current density.

Therefore, as the local magnetic fields H _A and H _B change depending on the direction of the current due to the application of the high-frequency current, a large change in the magnetic field occurs near y=0 compared to the end of the conductor plate 22. As a result, so-called hot spots are formed due to an increase in eddy currents. Here, the uniform magnetic field H ₀ is introduced to theoretically study the efficiency of eddy current generation depending on the magnitude of the amplitude of the local magnetic fields H _A and H _B , so it is not necessary in an actual case.

The local magnetic fields H _A and H _B correspond to the first and second high-frequency alternating magnetic fields 16 and 17 in FIG.
It is clear that the eddy current density in the region sandwiched by the second high-frequency alternating magnetic fields 16 and 17 increases. In FIG. 1, it is necessary to heat the lesion 2 within the human body 1, so even if FIGS. 4 and 5 are applied as they are, it is impossible to heat only the lesion 2. Therefore, heating is performed from multiple angles.

[Modified example]

The present invention is not limited to the embodiments described above, and the following modifications are possible, for example.

(a) As shown in Figure 7, magnetic cores 27, 28, 29,
30 is provided, and coils 31, 32, 33,
Wind up 34 and connect power supply ₁₅ via switch S1.
The first to eighth magnetic poles P ₁ to P ₈ may be formed by flowing a high frequency current through the magnetic poles as in the case of FIG. 3.

(b) A plurality of magnetic field generators 7 to 10 shown in FIG.
Instead of providing a magnetic field generating device 7, one magnetic field generating device 7 may be rotated around the lesion 2 to apply a high frequency alternating magnetic field from different angular positions. That is, after generating the first and second high frequency alternating magnetic fields with a single magnetic field generating device, the third and fourth high frequency alternating magnetic fields are generated.
A fifth and a sixth high frequency alternating magnetic field may be generated.

(c) In FIG. 3, the strength of the fifth to eighth magnetic poles P ₅ to _{P 8} may be further strengthened so that the magnetic flux (lines of magnetic force) penetrates into the vicinity of the lesion 2 in a U-shape.

(d) Magnetic poles P ₁ and P ₄ corresponding to the size of lesion 2
The interval between P ₂ and P ₃ may be adjustable. Furthermore, the first and second high-frequency alternating magnetic fields may be obtained without arranging the magnetic poles P ₁ and P ₂ and P ₃ and P ₄ facing each other.

〔Effect of the invention〕

As is clear from the above, according to the present invention, it is possible to easily heat a local area inside a three-dimensional object. Therefore, it is extremely useful for heat treatment of cancer, etc.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a local heating device according to an embodiment of the present invention, FIG. 2 is a side view showing a part of the - line in FIG. Fig. 4 is a plan view showing the relationship between the conductor plate and the local magnetic field for determining the density of eddy current in a two-dimensional conductor plate, and Fig. 5 is a plan view showing the first one in detail.
6 is a diagram showing the relationship between the position of the conductor plate on the y-axis of FIG. 4 and the eddy current density, and FIG. 7 is a plan view showing a modified magnetic field generator. It is. 1...Human body, 2...Cancer lesion, 3, 4, 5, 6...
Virtual straight line, 7, 8, 9, 10...Magnetic field generator, 1
1...first coil, 12...second coil, 13...
Third coil, 14... Fourth coil, 15... Power supply, 16... First high frequency alternating magnetic field, 17... Second high frequency alternating magnetic field, 18... Fifth coil, 19... Sixth coil, 20... 7th coil, 21...8th coil.

Claims (1)

[Scope of Claims] 1. A device for heating a local area within a conductive object, comprising a plurality of high-frequency alternating magnetic field generating devices provided corresponding to a plurality of virtual straight lines passing through the local area, and the high-frequency alternating magnetic field The generator is configured to generate a high frequency alternating magnetic field for causing an eddy current to flow within the object, and the high frequency alternating magnetic field generator has a first magnetic pole of a first polarity and a second magnetic pole of a second polarity. a second magnetic pole;
a third magnetic pole of the first polarity, a fourth magnetic pole of the second polarity, a fifth magnetic pole of the first polarity, a sixth magnetic pole of the second polarity, and a third magnetic pole of the second polarity. 7 magnetic poles and an eighth magnetic pole of a first polarity, the first magnetic pole is arranged along the straight line on one side of the object, and the second magnetic pole is arranged along the straight line on one side of the object. The third magnetic pole is disposed along the straight line on the other side of the object and is disposed opposite to the first magnetic pole in order to generate a first high-frequency alternating magnetic pole between the first magnetic pole and the third magnetic pole. is arranged along the straight line on the other side of the object, and the fourth magnetic pole is arranged along the straight line on one side of the object, and a second magnetic pole is arranged between the fourth magnetic pole and the third magnetic pole. are arranged to face the third magnetic pole in order to generate a high-frequency alternating magnetic field, and the fifth and sixth magnetic poles are arranged between the first magnetic pole and the fourth magnetic pole, and the fifth and sixth magnetic poles are arranged between the first and fourth magnetic poles. The seventh and eighth magnetic poles are arranged between the second magnetic pole and the third magnetic pole. and is set to generate a high-frequency alternating magnetic field for limiting the spread of the first and second high-frequency alternating magnetic fields, and by sequentially operating the plurality of high-frequency alternating magnetic field generators, the plurality of virtual straight lines are A local heating device in a conductive object, characterized in that it is configured to heat the local area corresponding to an intersection. 2. The local heating device in a conductive object according to claim 1, wherein the high frequency alternating magnetic field for preventing the spread is generated in synchronization with the first and second high frequency alternating magnetic fields.