JP2013215354A - Device for locally heating inside of body - Google Patents

Abstract

An object of the present invention is to provide a local body warming device for locally warming a target part to be heated even when the target part to be heated is deep in the body.
A power receiving unit and a heating unit are embedded in a body so that a target organ to be heated is sandwiched between a pair of electrodes and a receiving coil is disposed in a gap between surrounding organs. All the power transmission coils are arranged around the body, the power is supplied from the outside to the power transmission unit and an alternating current is caused to flow, thereby generating a variable magnetic field. The magnetic field generated from the power transmission unit is a ring-shaped hollow of the power reception coil 16 As a current flows through the power receiving coil 16 through the inside, power is transmitted wirelessly from the power transmitting unit outside the body to the power receiving unit 14 inside the body, and in the heating unit, an electric field is generated between the electrodes 20 by the power received by the power receiving unit 14. And the target organ to be heated sandwiched between the electrodes 20 is heated.
[Selection] Figure 7

Description

  The present invention relates to a local body warming device.

  Conventionally, for example, warming a target region in the body, such as treatment of deep cancer, has been performed.

  For example, it includes a cavity resonator, a high-frequency oscillator that supplies high-frequency power to the cavity resonator, a high-frequency amplifier, a tuning / matching circuit, and a control circuit that controls the high-frequency oscillator, high-frequency amplifier, and tuning / matching circuit. 2. Description of the Related Art A thermotherapy device having an electric field focusing means in a cavity resonator has been proposed as a thermotherapy device that heats an object to be treated using an electromagnetic field distribution in the chamber (see, for example, Patent Document 1). In the thermotherapy device described in Patent Document 1, the electric field or electric field distribution formed by the high-frequency power supplied to the cavity resonator is controlled by the dielectric that is the electric field focusing means, and the relative permittivity, shape, or It becomes a focused electric field based on the arrangement, and heats the heating region of the treatment object.

  In addition, a feeding means for feeding microcapsules in which ultrafine particles of ferromagnetic material are embedded in a ribosome having a biological component bonded to the surface thereof, and the ultrafine particles are derived together with blood from the vicinity of the cancer tissue. Deriving means, collecting means for collecting ultrafine particles derived by the deriving means, refluxing means for refluxing blood that has passed through the collecting means into the body, and ultrafine particles delivered to the vicinity of the cancer tissue There has been proposed a thermotherapy device configured to include resonance energy applying means for applying resonance energy to (see, for example, Patent Document 2). In the thermotherapy device described in Patent Document 2, resonance energy is imparted to the ultrafine particles delivered to the vicinity of the cancer tissue, and the cancer tissue is selectively heated by the resonance of the ultrafine particles.

JP 2006-254629 A Japanese Patent Laid-Open No. 4-198548

  However, in the technique described in Patent Document 1, the electric field is converged by the dielectric, but the converged electric field is irradiated from the surface of the body, so that the portion through which the electric field passes is heated. In the case where the temperature target region is a deep part in the body, the region other than the temperature target region is also heated.

  Also, in the technique described in Patent Document 2, since the entire body including the periphery of the region to be heated is resonated from the body surface, when the microcapsule is present in the vicinity of the normal region other than the cancer tissue, the normal region is added. There was a possibility of being heated.

  Thus, in the prior art, by heating the target region and its peripheral region from the body surface dielectrically, normal regions (for example, organs other than skin, muscle, cancer tissue) are heated, In order to avoid an increase in burden on the patient such as the occurrence of side effects, there has been a problem that sufficient heating cannot be performed such as limiting the heating time.

  The present invention has been made to solve the above problems, and provides a local in-vivo warming device capable of locally warming a target region even when the target region is deep in the body. The purpose is to do.

  In order to achieve the above object, a local warming device of the present invention is arranged outside a body of a subject and generates a magnetic field at a predetermined position of the subject, and the body of the subject. A flexible ring-shaped power receiving coil that is disposed between a peripheral part of the target part of heating or a plurality of the peripheral parts, and receives power generated by electromagnetic induction of a magnetic field generated from the magnetic field generating unit; The power receiving coil is configured to include at least a pair of electrodes that are electrically connected to both ends of the power receiving coil and disposed so as to sandwich the region to be heated. The electric power received by the power receiving coil generates an electric field between the electrodes. And a heating unit that locally heats the target region to be heated.

  According to the in-vivo local heating device of the present invention, when the magnetic field generator arranged outside the body of the subject generates a magnetic field at a predetermined position of the subject, the ring-shaped power receiving coil having flexibility is Electric power generated by electromagnetic induction of a magnetic field generated from a magnetic field generation unit is received in a state where it is arranged between a peripheral part or a plurality of peripheral parts in a subject's body. And the heating part comprised including at least a pair of electrodes which are electrically connected to each of both ends of the power receiving coil and are arranged so as to sandwich the region to be heated is provided between the electrodes by the power received by the power receiving coil. An electric field is generated to locally heat the target region to be heated.

  Thus, since magnetic field energy is used for transmission of electric power from outside the body to the inside of the body, it is possible to supply necessary electric power without heating. In addition, since the electric field energy applied by at least a pair of electrodes arranged so as to sandwich the target part is used for heating the target part, the target part sandwiched between the electrodes can be heated. Thereby, even when the target region to be heated is deep in the body, the target region to be heated can be locally heated.

  In addition, an insulating material is provided around each of the electrodes so that an insulation resistance around a surface not in contact with the heating target portion is higher than an insulation resistance around the surface in contact with the heating target portion of each of the electrodes. Can be provided. The insulating material may be provided so as to cover the whole or a part of each of the electrodes, may be provided so as to spread from the electrode side toward the region to be heated, or provided independently around the electrode. Also good.

Thereby, the direction to heat can be controlled and it can suppress more that parts other than the warming object part pinched between electrodes are heated.

  Moreover, the outer periphery of the said receiving coil can be coat | covered with an insulating material. Thereby, the influence which it has on the peripheral site | part by which the receiving coil is arrange | positioned can be suppressed.

  As described above, according to the in-vivo local heating device of the present invention, magnetic field energy is used for power transmission from the outside of the body to the body, and electric field energy is used for heating the target region. Even when the target part is deep in the body, the effect that the target part to be heated can be locally heated is obtained.

It is the schematic which shows the in-vivo local heating apparatus which concerns on this Embodiment. It is the schematic which shows a power transmission part. It is the schematic which shows the other example of a power transmission part. It is the schematic which shows a power receiving part. It is a schematic sectional drawing of a receiving coil. It is the schematic which shows the electrode part of a receiving part. It is the schematic which shows the state which has arrange | positioned the power receiving part in the body. It is a figure which shows the equivalent circuit of the in-vivo local heating apparatus which concerns on this Embodiment. It is the schematic which shows the other example of the electrode part of a receiving part. It is an image figure which shows the analysis model of a present Example. It is a SAR distribution map in the horizontal section which shows the analysis result of a present Example. It is a SAR distribution map in the section seen from the side which shows the analysis result of a present example. It is a SAR distribution map in the cross section seen from the back which shows the analysis result of a present Example. It is an image figure which shows the analysis model of the conventional hyperthermia. It is a SAR distribution map which shows the analysis result by the analysis model of the conventional hyperthermia. It is an image figure which shows the analysis model which coat | covered the electrode with the insulating material. It is a SAR distribution map which shows the analysis result by the analysis model which coat | covered the electrode with the insulating material. (A) Schematic which shows the electrode part containing the insulating material in another Example, (b)-(d) The image figure which shows an insulating material addition model. It is an image figure which shows the insulating material addition model in another Example. It is a SAR distribution map which shows the analysis result by (a) normal model and (b) insulation material addition model.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, local in-vivo warming device 10 according to the present embodiment includes power transmission unit 12 disposed outside the body, power receiving unit 14 and heating unit 19 disposed in the body. ing.

The power transmission unit 12 is disposed outside the body and generates a magnetic field when electric power is supplied from the outside. For example, as shown in FIG. 2, the power transmission unit 12 can be an N _1- turn power transmission coil and is arranged around the human body. In addition, the form of the power transmission unit 12 is not limited to the case where the power transmission unit 12 is arranged around the human body as described above, and may be arranged on one side of the human body as illustrated in FIG. What is necessary is just to arrange | position so that a magnetic field may generate | occur | produce toward the done body.

  As shown in FIG. 4, the power receiving unit 14 includes a power receiving coil 16 that receives power generated by electromagnetic induction of a magnetic field generated from the power transmitting unit 12, and an insulating material 18 that covers the outer periphery of the power receiving coil 16. Has been.

Receiving coil 16 is a ring-shaped N _2-turn coil having a flexibility. Considering that the power receiving unit 14 is disposed in the body, it is desirable that N ₂ is about twice in order to prevent the power receiving unit 14 itself from becoming thick. Further, the larger the area of the hollow portion of the power receiving coil 16 formed in a ring shape, the higher the power transmission efficiency can be obtained. Moreover, the larger the area of the hollow portion, the lower the power density passing through the living tissue, and the power absorption into the living body can be reduced. Considering this point, the size of the power receiving coil 16 is determined so that the area of the formed ring-shaped hollow portion has an appropriate size. For example, when the power receiving unit 14 is embedded in the abdomen, the size of the hollow portion of the power receiving coil 16 in a state where the power receiving coil 16 is disposed in the body is about 100 to 140 cm ² . As a material for the power receiving coil 16, polyurethane or the like can be used to ensure flexibility.

As the insulating material 18, an insulating material having a thickness of about 2 to 4 mm can be used. The insulating material 18 is a material having flexibility so as to follow the deformation of the receiving coil 16 having flexibility. The insulating material 18 covers the power receiving coil 16 so that the N ₂ winding portion of the power receiving coil 16 forms one ring. FIG. 5 shows a schematic diagram of the AA ′ cross section in FIG. 4 in the case of N ₂ = 2 times. 5 shows a case where the cross-sectional shape is an ellipse, the present invention is not limited to this, and the power receiving coil 16 may be covered with the insulating material 18 so as to have an eight-shaped cross section.

  The heating unit 19 includes a pair of electrodes 20 that are electrically connected to both ends of the power receiving coil 16 and an insulating material 22 that covers a part of the electrodes.

  The electrode 20 can be made of a conductive material such as copper, aluminum, stainless steel copper, titanium, platinum, or silver. The size of the electrode 20 can be an appropriate size depending on the size of the organ to be heated sandwiched between the electrodes. For example, the electrode 20 can be a circular shape in plan view with a thickness of about 1 cm and a diameter of about 2 cm. The shape of the electrode 20 is not limited to this shape, and may be a rectangle, a square, an ellipse, or the like. As the insulating material 22, an insulating substance having a thickness of about 2 to 4 mm can be used.

  FIG. 6 shows an enlarged schematic view around the heating unit 19. The electrode 20 is electrically connected to each of the start point and the end point of the power receiving coil 16, and is disposed with the target organ to be heated sandwiched between the electrodes 20. The electrode 20 has a surface exposed to the organ to be heated exposed and the other surface covered with an insulating material 22.

  As shown in FIG. 7, the power receiving unit 14 and the heating unit 19 are embedded in the body so that the target organ to be heated is sandwiched between the pair of electrodes 20 by an implantation operation such as a laparotomy operation or an endoscopic operation. Further, the power receiving coil 16 having flexibility is arranged between a peripheral organ or a plurality of peripheral organs existing around the organ to be heated. The case where it is arranged in a peripheral organ is, for example, a case where it is arranged inside the stomach, intestine, lung or the like. Moreover, the case where it arrange | positions between several peripheral organs is a case where it arrange | positions in the clearance gap between a peripheral organ and a peripheral organ, or a case where it arrange | positions between the closely-contacted peripheral organs. In the disposed state, peripheral organs may enter the hollow portion of the power receiving coil 16 that forms a ring shape. It is not necessary to arrange the ring shape of the power receiving coil 16 in the body while maintaining a perfect circle, and it is possible to secure the power necessary for warming the organ to be warmed considering that the received power is proportional to the area of the hollow portion. The receiving coil 16 part should just be arrange | positioned in the shape which becomes the area of a hollow part of a grade.

  The power receiving unit 14 and the heating unit 19 can be inserted from the mouth or the like without depending on the operation, and can be disposed in the stomach, the intestine, the lung, or the like, for example. In this case, the heating unit 19 can locally heat the stomach, the inner wall of the intestine, and the like.

  Next, the action of the local body warming device 10 according to the present embodiment will be described with reference to FIG. 8 showing an equivalent circuit of the local body warming device 10 according to the present embodiment.

  First, as shown in FIG. 7, the power receiving unit 14 and the heating unit 14 are placed so that the organ to be heated is sandwiched between the pair of electrodes 20 and the power receiving coil 16 is arranged between the peripheral organ or the plurality of peripheral organs. The warm part 19 is embedded in the body. And the power transmission coil as the power transmission part 12 is arranged around the body.

  Next, a fluctuating magnetic field is generated by supplying electric power from the outside to the power transmission coil as the power transmission unit 12 and causing an alternating current to flow. A current flows through the power receiving coil 16 when the magnetic field generated from the power transmitting unit 12 passes through the hollow space of the ring-shaped power receiving coil 16. Thereby, electric power is transmitted wirelessly from the power transmission unit 12 outside the body to the power reception unit 14 inside the body, and the heating unit 19 generates an electric field between the electrodes 20 by the power received by the power reception unit 14. The organ to be heated sandwiched between the electrodes 20 is heated by the electric field generated between the electrodes 20.

  The living tissue is not heated by the passage of the magnetic flux from the outside of the body to the inside of the body, and the living tissue is heated at the location where the electric field passes. Therefore, the part of the target organ to be heated sandwiched between the electrodes 20 is locally Will be heated.

  As described above, according to the in-vivo local warming device 10 of the present embodiment, magnetic field energy is used for power transmission from outside the body to the body, and electric field energy is used for heating the target site. Even when the target region to be heated is deep in the body, the target region to be heated can be locally heated.

  Further, by reducing the number of turns of the power receiving coil 16 so that the thickness does not increase, the power receiving unit 14 can be arranged between the peripheral organs and the peripheral organs. Can be suppressed. Moreover, since electric power is wirelessly transmitted between the power transmission unit 12 and the power reception unit 14, the electric wire for supplying power to the power reception unit 14 can be used for a long time without penetrating the skin. Such a configuration eliminates the need to connect the inside and outside of the living body with a wire, and thus is effective in preventing infection over time.

  The receiving coil for wireless power transmission of the prior art is made as small as possible in order to suppress the influence on the living body, and is a disk-shaped coil (for example, an outer diameter of about 7 cm, an inner diameter of about 2 cm, and a thickness of about 1-2 mm). In general, there was a method of embedding between the organ and between the skin and the muscle layer (reference reference “Takeji Shiba et al.,“ Air-core transcutaneous energy transmission system for artificial heart-Stabilization of output voltage by extracorporeal information) Control- ", Biomedical Engineering, Vol.43 (2005), No.4 pp.670-676"). However, when power is sent to a power receiving unit arranged in the body using energy transmission of a magnetic field, the larger the area of the power receiving coil, the higher the transmission efficiency, but it is possible to increase the area of the power receiving coil. , Conflicting in that the effect on the living body becomes large.

  On the other hand, in the in-vivo local heating device 10 according to the present embodiment, the power receiving coil 16 is formed into a ring shape having flexibility, so that the influence on the living tissue or organ is suppressed and embedded in the body. be able to. Furthermore, the area of the ring-shaped hollow portion formed by the power receiving coil 16 can be increased, and high transmission efficiency can be obtained while reducing the influence on the living body.

  The electrode 20 may be a bag electrode as shown in FIG. The bag electrode shown in FIG. 9 is configured by putting a conductive solution 220 into a bag made of an insulating material 222 to form an electrode. The insulating material 222 is made of a flexible material, and the surface that does not contact the organ to be warmed increases the insulation resistance, and the surface that contacts the organ to be warmed extremely decreases the insulating resistance. The level of the insulation resistance can be adjusted by changing the thickness of the insulating material 222 or changing the material. By using such a bag electrode, the bag electrode itself has flexibility, so that the surface in contact with the organ to be warmed can be deformed to match the shape of the organ, and the surface of the bag electrode is placed on the organ to be warmed. It can be adhered. Compared with the case where the contact point between the electrode and the organ to be heated is one point, current concentration can be prevented, and unnecessarily warming can be prevented. In addition, by using the bag electrode, since all of the power receiving unit 14 is made of a flexible material, when embedding the power receiving unit 14 in the body, it can be inserted from a small hole opened in the body, An implantation operation can be performed endoscopically without the need for a laparotomy.

<Example>

  Examples will be described below. In this embodiment, the configuration shown in FIGS. 1, 2, and 4 is used to verify a configuration for heating a part of the pancreas as a target region to be heated by electromagnetic field analysis. In the verification, we used the abdomen of the average human body model (TARO) of Japanese men provided by NICT as shape data as a human body model that has the same electrical characteristics and shape as the human body. A model in which the relative permittivity (Table 1) was input was used as a human body model. The conductivity and relative dielectric constant were values at a frequency of 2 MHz of electromagnetic field energy.

  In Table 1, the conductivity (Conductivity σ) is Siemens per unit length (1 m), and the dielectric constant (Relative permittivity) is the dielectric constant ratio of each organ (Organ) to the dielectric constant of vacuum.

  Table 2 shows the specifications of the power transmission unit 12, Table 3 shows the specifications of the power reception unit 14, and Table 4 shows the electromagnetic field analysis method. An analysis model is shown in FIG. The figure (a) is the power transmission part 12 portion arranged around the human body model, the figure (b) is the body part where the power transmission part 12 is arranged, the figure (c) is the power transmission part 12, and the pancreas (warming target organ). FIG. 4D shows a portion where the power transmission unit 12 and the pancreas are extracted, and FIG. 5E shows a portion where the electrode 20 and the pancreas are extracted. Here, the pancreas is sandwiched between metal electrodes. As an evaluation index for heating, SAR (absorbed power per unit mass of living tissue [W / kg]) was used.

  The analysis results of SAR are shown in FIGS. 11A and 11B are horizontal cross sections of an analysis model including a pancreas portion, and FIGS. 11C to 10F are analysis results in the same cross section. (C) shows 0 to 30 W / kg, (d) 0 to 10 W / kg, (e) 0 to 2 W / kg, (f) 0 to 0.35 W / kg. Yes. As shown in FIGS. 5C to 5F, it can be seen that the SAR of the biological tissue between the electrodes 20 (point X, indicated by a dotted line in FIGS. The point X is a value close to 30 W / kg, while the other portions are 0.35 W / kg even in the portion where the SAR is large (point Y). ICNIRP defines that the local SAR that does not affect the living body is 10 W / kg or less. From FIGS. 9D and 9E, the SAR is 10 W / kg at points other than the point X. It is less than kg and it turns out that it is safe. 12A is a cross-sectional view of the analysis model including the pancreas portion as viewed from the side, and FIG. 12B is an analysis result of the cross-section, and FIG. 13A is a back view of the analysis model including the pancreas portion. The cross section seen from FIG. 2B and FIG. 2B are analysis results in the same cross section. 12 and 13 also show that the SAR is increased only in the living tissue between the electrodes 20.

In addition, Fig. 14 shows a conventional hyperthermia analysis model (reference: supervised by the Japan Hyperthermia Society, "Fully revised Hyperthermia Manual", published on September 3, 1999, 1st page, page 245). Is shown in FIG. The result shown in FIG. 15 is the SAR distribution of the cross-sectional view of the central portion of the analysis model shown in FIG. 14, and shows the ratio (%) obtained by dividing the SAR value at each position by the maximum value. From this point, when considering the case where the region to be heated is in the center of the muscle (point X ₀ ), the point X ₀ is a value lower than 10%, but the SAR of the living tissue in the region in contact with the electrode bolus It can be seen that (Point Y ₀ ) is 40 to 50%. The ratio of the SAR at the point X ₀ and the point Y ₀ is about 1: 5, which indicates that other normal tissues are heated five times as much as the target region to be heated. On the other hand, in the present embodiment, the ratio of SAR at point X and point Y is 85: 1, and the target region to be heated can be heated 85 times more than normal tissue, and only the target region is localized. It can be seen that this is a method that can be heated.

  In the analysis model in the above embodiment, copper (Cu) is used as the electrode 20, but the same SAR analysis result is obtained even in an analysis model using titanium whose conductivity is one digit smaller than copper as the electrode 20. It was. When titanium is used as the electrode 20, the influence on the living body can be further suppressed.

  In the analysis model in the above embodiment, the organ to be heated (pancreas) is sandwiched by using the electrode 20 that is not covered with the insulating material 22. By covering the electrode 20 with the insulating material 22, it is possible to prevent current from flowing to surrounding organs not to be heated. FIG. 16 shows an electromagnetic field analysis model calculated by electromagnetic field analysis in the case of covering with an insulating sheet having a thickness of 3 mm, and FIG. 17 shows the SAR distribution. In FIG. 16, peripheral organs are omitted around the pancreas. However, when actually performing electromagnetic field analysis, the analysis is performed with the peripheral organs attached. Table 5 shows electrical constants of the insulating material 22 and the electrode 20. The insulating material 22 is made of silicone, and the electrode 20 is made of titanium.

  FIG. 17 shows an equal SAR surface between the electrodes 20, and when the frequency of the electromagnetic wave exceeds 60 MHz, the current passes through the insulating material 22, and the organ outside the electrode 20 also has a high SAR. In the following, it can be seen that the SAR outside the electrode is small.

  Next, another embodiment will be described. In this embodiment, the configuration of the insulating material provided around the electrode is changed in order to prevent the current from flowing to the organs of the surrounding tissue other than the region to be heated. For example, FIGS. 18A to 18D show an example in which another insulating material 22b (two sheets) is attached to the insulating material 22a covering the electrode 20 like a wing. An independent insulating material 22c is also inserted between the pancreas and spleen.

  As shown in FIG. 18, when the insulating material 22 is only around the electrode (without wings) (normal model) in order to investigate the warming state of the organ to be heated and the surrounding organ by adding the insulating material. In the case where the insulating materials 22a to 22c were provided (insulating material additional model), the SAR distributions when the same power was sent were compared by electromagnetic field analysis.

  The SAR distribution of the BB ′ cross section in the analysis model shown in FIG. 19 is shown in FIG. 20A for the normal model and in FIG. Note that the SAR distribution is not displayed in the pancreas, which is the organ to be heated, and all the parts that can be displayed are organs other than the pancreas. Therefore, the white part in FIG. Corresponds to the warm part.

  FIG. 20A shows that the SAR distribution is white in the spleen portion, and the SAR is increased. On the other hand, in FIG. 5B, the white part of the SAR distribution is reduced, and it can be seen that the SAR is small. The total power absorbed by the pancreas is 90.5% of the total power transmitted from the power source: 92.4% of the additional insulation material model, and the spleen as a representative of the surrounding organs. Normal model: additional insulation material model The ratio of 1.98%: 0.6% (the ratio of power absorbed by the pancreas is normal model: insulation material additional model = 0.03W: 0.009W), and the addition of insulation material prevents the surrounding organs from warming I found it effective.

DESCRIPTION OF SYMBOLS 10 Body local heating apparatus 12 Power transmission part 14 Power receiving part 16 Power receiving coil 18 Insulating material 20 Electrode 22 Insulating material

Claims (3)

A magnetic field generator disposed outside the body of the subject and generating a magnetic field at a predetermined position of the subject;
A flexible ring that is disposed between a peripheral region or a plurality of peripheral regions in the body of the subject and receives electric power generated by electromagnetic induction of a magnetic field generated from the magnetic field generation unit. A power receiving coil
The power receiving coil is configured to include at least a pair of electrodes that are electrically connected to both ends of the power receiving coil and disposed so as to sandwich the region to be heated. The electric power received by the power receiving coil generates an electric field between the electrodes. And a heating unit for locally heating the target area for heating,
In-body local warming device.   An insulating material is provided around each of the electrodes so that an insulation resistance around a surface not in contact with the heating target portion is higher than an insulation resistance around the surface in contact with the heating target portion of each of the electrodes. The in-vivo local heating apparatus according to claim 1.   The in-vivo local heating apparatus according to claim 1 or 2, wherein an outer periphery of the power receiving coil is covered with an insulating material.