JP2015093100A - Heating probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating probe that enables heating by an electromagnetic wave, and also enables precise temperature measurement of the center of a heating part.SOLUTION: A heating probe 17 is provided for heating a heating object in the vicinity of a tip of a needle 18 of the probe 17 by radiating an electromagnetic wave. An inner conductor is projected by a predetermined length more than an outer conductor in the tip part of the needle of a coaxial cable structure. The inner conductor is a thin cylindrical metal, and a thermocouple being a temperature sensor 20 comprises the inner conductor as one metal (copper) for constituting the thermocouple. The other metal (constantan) line is applied with insulating coating and is built in the inside of the cylindrical metal, and comes into contact with the cylindrical metal of the inner conductor only at the tip part of the needle.

Description

The present invention relates to a heating probe, and more particularly to a heating probe capable of measuring the temperature of a heating unit simultaneously with heating.

2. Description of the Related Art Conventionally, various heating devices including probes for inserting into an affected area such as a malignant tumor and heating the affected area with electromagnetic waves such as microwaves to kill (coagulate) have been proposed. For example, Patent Document 1 below discloses a coaxial antenna for microwave coagulation therapy. The antenna device includes an external electrode 2 and a center electrode 4 provided inside the external electrode 2 via an insulator 3, and the central electrode 4 is provided at a portion protruding from the tip of the external electrode 2. A connected microwave irradiation part (antenna) 5 is formed.

JP 2007-029457 A

In microwave heating (coagulation) therapy, it is necessary to control the temperature of the affected area to be heated. However, in the conventional microwave coaxial antenna as described above, in order to measure the temperature of the affected area, the temperature is separately measured. Since the method of inserting the probe into the affected part and measuring the temperature of the affected part has been taken, there is a problem that the temperature at the center of the heated part cannot be measured accurately. In particular, when the affected area is small, such as an early malignant tumor, it is difficult to place a plurality of (antenna and temperature sensor) probes at the center of the affected area.

In addition, the radiation pattern is affected by the temperature measurement probe, and the burden on the patient is increased by inserting a plurality of probes into the affected area. An object of the present invention is to solve the above-mentioned conventional problems and to provide a heating probe capable of accurately measuring the temperature of the center of a heating unit simultaneously with heating.

The heating probe of the present invention is a heating probe that heats an object to be heated near the tip of the probe needle by radiating electromagnetic waves, and the inner conductor of the probe is more external than the outer conductor at the tip of the probe needle of the coaxial cable structure. Also, the main feature is that a temperature sensor is protruded by a predetermined length and a temperature sensor is disposed inside the protruding inner conductor.

Further, the above-described heating probe is characterized in that the temperature sensor is a thermocouple having an inner conductor as one metal. In the heating probe described above, the inner conductor is a thin cylindrical metal, the thermocouple has the inner conductor as one metal, and the other metal wire constituting the thermocouple has an insulating coating. It is also characterized in that it is built in the cylindrical metal and is in contact with the cylindrical metal of the inner conductor only at the tip of the probe needle.

In the heating probe described above, at the rear end of the probe needle, the metal tube constituting the inner conductor is connected to a strip line or a coaxial cable to which electromagnetic waves are supplied, and influences the supply of electromagnetic waves. There is also a feature in that a separation circuit is provided for drawing out the two types of metal wires constituting the thermocouple as they are from the electromagnetic wave transmission line without giving them.

The present invention has the following effects. (1) Accurate temperature measurement at the center of the electromagnetic wave supply destination is possible without affecting the radiation distribution of the electromagnetic wave, so there is a variation in the heating rate due to the difference in electromagnetic wave absorption caused by individual cancer cell differences. However, it is possible to control the temperature to be kept at an optimum state by adjusting the electromagnetic wave power, and the influence on the surrounding normal cells can be minimized.

(2) Since a very thin needle of 0.5 mm or less can be manufactured by the structure of the present invention, it can be inserted without anesthesia like an acupuncture needle, and the burden on the patient can be reduced. (3) Since the heating range can be reduced by the structure of the present invention, and the temperature of a heated part of a small affected part such as an initial cancer can be accurately controlled, a small diameter (5 mm) that can be found with improved detection capability. The following non-incision treatment of initial cancer is possible.

FIG. 1 is a block diagram showing the configuration of an example of use of a heating apparatus using the heating probe of the present invention. FIG. 2 is a plan view and a side view showing the configuration of the heating probe of the present invention. FIG. 3 is a cross-sectional view showing a configuration example of the needle of the heating probe of the present invention.

Embodiments will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an example of use of a heating apparatus using the heating probe of the present invention. The heating device 10 includes a CPU 11, a panel 12, a high frequency power supply circuit 13, and a temperature measurement circuit 14. The heating probe 17 of the present invention includes a needle 18 and is connected to the heating device 10 by a flexible printed wiring board 15 and a thermocouple wire 16 constituting a strip line. The characteristic impedance of the strip line is designed to be a constant value (for example, 50 ohms), and a material having a dielectric loss as small as possible is adopted as the material of the substrate.

The heating device 10 using the heating probe 17 of the present invention pierces the tip of the needle 18 at the center of the affected part (heating target) 26 of the living body 25 while using, for example, an ultrasonic 3D image capturing device or the like. Is used to heat the affected part 26 by supplying microwaves through the flexible printed wiring board 15 and radiating it from the tip part of the needle 18 to the surroundings to kill the affected part cells. The reason for using the flexible printed wiring board is that the flexible printed wiring board is more flexible than the coaxial cable, and prevents the tip position of the needle 18 from moving due to an undesired force applied to the heating probe 17. Because.

The CPU 11 of the heating device 10 is a well-known program control controller having a CPU, ROM, RAM, digital input / output terminal, analog input terminal (A / D conversion circuit), etc., and an arbitrary CPU having a necessary function. It can be adopted. As the CPU 11 of the heating device 10, a commercially available CPU measures the temperature of the affected area based on the setting of the temperature and time from the panel 12, so that the affected area is heated at a predetermined temperature for a predetermined time. A temperature management program that controls the output power of the circuit 13 is created and written.

The high frequency power supply circuit 13 is a known high frequency power supply circuit that uses a transistor and can output a microwave of about several tens of watts at a maximum of 2.45 GHz, for example, based on control from the CPU 11. The output section is provided with a known matching circuit for matching the strip line 15, the needle 18, the transmission path, and the antenna portion at the tip of the needle. Further, the output unit is a DC cut circuit using a capacitor or a coupler in order to prevent current from the power source from flowing into the thermocouple wire.

In addition, as a transistor of the high frequency power supply circuit 13, a transistor having a large allowable power is adopted assuming total reflection. Moreover, you may provide a circulator and a fixed attenuator between a transistor and a matching circuit as needed.

The temperature measurement circuit 14 differentially amplifies the voltage generated from the thermocouple at the terminal 21 with a predetermined amplification factor, and outputs the differential amplifier 22 to the analog input terminal of the CPU 11 and a terminal for correcting the measured value of the thermocouple. A terminal temperature sensor 20 that measures the temperature of 21 and outputs it to the analog input terminal of the CPU 11 is provided.

The thermocouple wire 16 is a connecting electric wire in which two types of metal constituting the thermocouple arranged at the tip of the needle 18 are drawn out as they are, and between two terminals 21 of the same type (for example, copper) metal. A voltage proportional to the temperature difference between the tip of the needle 18 and the terminal 21 is generated. The CPU 11 calculates the temperature of the tip of the needle 18 based on the voltage output from the differential amplifier 14 and the voltage output from the terminal temperature sensor 20 so that the tip reaches a desired temperature set in the panel. The high frequency power supply circuit 13 is controlled. The terminal 21 may be housed in a constant temperature bath and cooled with ice or the like.

The needle 18 of the heating probe 17 will be described in detail later. For example, the needle 18 of the heating probe 17 has a length of about 100 mm and a diameter of about 0.5 mm, and is provided with an antenna portion that radiates microwaves at the tip portion. Built-in temperature sensor consisting of thermocouple.

FIG. 2 is a plan view and a side view showing the configuration of the heating probe of the present invention. In the upper plan view, the state in which the upper case 30 is removed is shown, and in the lower side view, the upper and lower cases 30 and the flexible printed wiring board 15 are cut out in half.

The case 30 of the heating probe 17 is divided into an upper surface and a lower surface. The case 30 is fixed with the needle 18 and the flexible printed wiring board 15 constituting the strip line interposed therebetween, and is fixed to each other with screws (not shown). The flexible printed wiring board 15 is provided with two positioning holes 39 that engage with protrusions provided on the inner surface of the case 30.

Further, the outer conductor at the rear end of the needle 18 is fixed to a connecting plate 36 made of a metal plate by soldering or the like, and this connecting plate 36 is provided on the lower surface and the upper surface of the three-layer flexible printed wiring board 15 constituting the strip line. The ground layers 37 and 38 are fixed to each other by a conductive adhesive, a spring, pressure bonding, or the like.

A cylindrical metal 31 which is an inner conductor drawn out from the needle 18 at the rear end portion of the needle 18 is connected to a strip line conductor 32 to which electromagnetic waves are supplied, and is further extended from the connection point 35 to form a case 30. And is connected to the input terminal 21 of the temperature measurement circuit 14 of the heating device 10 as a thermocouple wire 16.

The cylindrical metal 31 has two chip capacitors 33 (for example, a capacity of 100 pF × 2) at a predetermined length corresponding to the length of a quarter wavelength at the microwave frequency used from the connection point 32. Is grounded to the ground layer 38 on the upper surface of the flexible printed wiring board 15. The one-layer printed wiring board 34 bonded to the ground layer 38 on the upper surface of the flexible printed wiring board 15 includes lands for connecting and holding the cylindrical metal 31 and the two chip capacitors 33. A part of the ground layer 38 on the upper surface of the flexible printed wiring board 15 may be separated and used as a land. In this case, however, it is necessary to dispose the land far from the center of the stripline. A feedthrough capacitor may be used instead of the chip capacitor.

Since the two chip capacitors 33 are almost equivalent to being directly grounded at the microwave frequency, the length of 1/4 wavelength is obtained at the microwave frequency using the cylindrical metal 31 from the connection point 32. Is set to a predetermined length (for example, about 3 cm for 2.45 GHz), the impedance of the cylindrical metal 31 viewed from the transmission path (connection point 32) becomes very large, and transmission of microwaves is possible. No effect.

That is, the cylindrical metal 31 and the two chip capacitors 33 that are the thermocouple wires in the case 30 connect the two types of metal wires (cylindrical metal 31) constituting the thermocouple without affecting the supply of electromagnetic waves. A separation circuit for drawing out from the electromagnetic wave transmission path (connection point 32) as it is is constituted.

Further, since the cylindrical metal 31 has an inductance, a low-pass filter circuit is formed by the two chip capacitors 33 and the cylindrical metal 31. Therefore, for example, the separation circuit may be configured by increasing the inductance of the cylindrical metal 31 by winding the cylindrical metal 31 in a coil shape or passing the cylindrical metal 31 through a ferrite bead. If it does in this way, the full length of the cylindrical metal 31 can be shortened, and the case 30 can be reduced in size and weight.

FIG. 3 is a cross-sectional view showing a configuration example of the needle of the heating probe of the present invention. 3A shows a longitudinal section and a transverse section of the central portion of the needle 18, and FIG. 3B shows a longitudinal section of the distal end portion of the needle 18. As shown in FIG. The needle 18 has a concentric five-layer structure. When a plating layer on the surface (not shown) is inserted, the needle 18 has six layers. The needle 18 includes a constant wire 46 from the center, an insulating layer 45, a copper tube layer 44, a thin cylindrical metal made of foil, a thick film, a dielectric layer 43, and an external copper tube layer 42 made of a metal tube or foil. It has become.

The surface of the external copper tube layer 42 is coated with a nickel-gold plating or an insulating resin (not shown). The cylindrical metal 31 and the thermocouple wire 16 described above are composed of a constantan wire 46, an insulator layer 45, and a copper tube layer 44. A coaxial cable structure serving as a microwave transmission path is formed by the copper pipe layer 44, the dielectric layer 43, and the outer copper pipe layer 42 which are inner conductors. The characteristic impedance of the needle 18 is designed to be about 50 ohms, and the dielectric layer 43 is made of a material having a small dielectric loss.

At the tip of the needle 18, the copper tube layer 44 that is the inner conductor of the coaxial cable structure protrudes together with the dielectric layer 43 by a predetermined length from the outer copper tube layer 42 that is the outer conductor. Form an antenna. The tip of the protrusion 51 is pointed conically. Further, the insulating layer 45 does not exist at the tip of the protruding portion 51, and the constantan wire 46 and the copper tube layer 44 are in direct contact, and this contact portion forms a thermocouple 50 that serves as a temperature sensor. doing. In addition, as the two kinds of metals constituting the thermocouple, any known combination can be adopted.

The length of the protrusion 51 is adjusted to 0.5 mm to several mm according to the affected part. Since the antenna radiating section is thin and short, the amount of reflected microwaves increases, but matching is achieved by a matching circuit provided in the output section of the microwave power supply circuit 13. As a result of the experiment, it was confirmed that even when the antenna part was 0.5 mm long, microwaves were radiated and the surrounding part of the antenna was heated to a temperature necessary for killing the gun. In order to increase the apparent length of the antenna portion, the dielectric layer 43 of the antenna portion may be made of a high dielectric constant, or the inner conductor may be wound in a coil shape.

As a manufacturing method of the thermocouple 50 used as a temperature sensor, it can manufacture using hybrid construction methods, such as a plating construction method, a vapor deposition construction method, an adhesion construction method, and a ceramic construction method. For example, a portion other than a few millimeters at the tip of the constantan metal wire antenna is coated with a known heat-resistant and insulating resin, and then a copper foil (copper tube) is formed on the surface of the wire by plating or vapor deposition. Thus, a long thermocouple wire whose tip is a thermocouple can be manufactured.

As a probe needle manufacturing method, first, a dielectric layer is formed by coating a thermocouple wire with a dielectric resin, and if necessary, the periphery is cut to adjust the diameter to a predetermined value. Thereafter, an external copper tube layer is formed on the surface of the coated thermocouple wire by copper plating or copper deposition. Alternatively, the outer copper pipe layer is formed by using a rolling (drawing) method, putting a coated thermocouple wire into a slightly larger copper pipe, and rolling (drawing) it through a die of a predetermined size. Form. Finally, the tip of the needle is ground and sharpened with a lathe with a symmetrical blade or a grindstone.

Although the embodiments have been described above, the following modifications are also conceivable. In the embodiment, an example in which the frequency of the microwave is 2.45 GHz is disclosed. However, the frequency is arbitrary, and the higher one improves the radiation efficiency even if the antenna is shorter, and more precisely heats only a small affected part. I can do it.

The length of the protruding portion (antenna portion) 51 is arbitrary, and it is possible to minimize the influence on normal cells by selecting a heating probe corresponding to the size of the cancer affected area.

In the embodiment, the example in which the heating probe and the heating device are connected by the strip line has been disclosed. However, the length of the strip line may be shortened and connected to the coaxial cable in the middle to be connected to the heating device.

The present invention can be applied to a heating device using any electromagnetic wave that requires temperature control.

DESCRIPTION OF SYMBOLS 10 ... Heating device 11 ... CPU 12 ... Panel 13 ... High frequency power supply circuit 14 ... Temperature measurement circuit 15 ... Flexible printed wiring board (strip line) 16 ... Thermocouple wire 17 ... Heating probe 18 ... Needle 20 ... Terminal temperature sensor 21 ... Terminal 22 ... Differential amplifier 25 ... Living body 26 ... Affected part (heating target)

Claims (4)

In a heating probe that heats an object to be heated near the tip of the probe needle by radiating electromagnetic waves, the inner conductor of the probe protrudes by a predetermined length from the outer conductor at the tip of the probe needle of the coaxial cable structure. And a temperature sensor is disposed inside the protruding inner conductor. The heating probe according to claim 1, wherein the temperature sensor is a thermocouple having an inner conductor as one metal. The inner conductor is a thin cylindrical metal, the thermocouple has the inner conductor as one metal, and the other metal wire constituting the thermocouple is provided with an insulating coating inside the cylindrical metal. The heating probe according to claim 2, wherein the heating probe is built-in and is in contact with the cylindrical metal of the inner conductor only at the tip of the probe needle. At the rear end of the probe needle, the metal tube constituting the inner conductor is connected to a strip line or a coaxial cable to which electromagnetic waves are supplied and constitutes a thermocouple without affecting the supply of electromagnetic waves. The heating probe according to claim 3, wherein a separation circuit for pulling out two types of metal wires as they are from an electromagnetic wave transmission path is provided.

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