RU2735496C1 - Microwave device for destruction of pathologically changed body tissues - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medical equipment. Microwave device made in the form of a trocar from a metal tube with a microwave coaxial waveguide placed inside the trocar tube with the possibility of insertion and removal from the tube containing an outer shell from medical steel filled with fluoroplastic, and central conductor located along waveguide axis, including at electrically controlled proximity end of waveguide electrically controlled matching device and microwave connector for connection to microwave generator, according to the invention, additionally comprises a power controller in the form of a controller, connected to the center conductor through the decoupling from the microwave signal, distal end of waveguide is equipped with reflecting tip of medical steel of cone shape with acute angle at vertex with cavity inside, inner walls of which are covered with microwave dielectric, inside the cavity there is an extension of the central conductor, the end of which is welded by spot welding to the body of the tip, forming a thermocouple, at the distal end there is a slit radiator with an opening angle of 450 to 900 to form a sector directional pattern, on the outer side of the waveguide there is a sliding holder made of foil for changing parameters of the radiator, with length not less than the slot length.

EFFECT: technical result consists in formation of sector directional diagram with elimination of microwave breakdown.

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Description

The invention relates to the field of medical technology and can be used in medicine for the destruction of pathologically altered tissues of the human body in the form of neoplasms and other pathologies, mainly deep bedding.

Various devices for microwave exposure are known, which include medical microwave emitters, antenna probes, attachments and other necessary units in the form of a generator, matching elements, connectors, waveguides, etc. (see, for example, inventors' certificates SU No. 1607827, No. 1819635, RU patents for inventions No. 2015699, 2086270).

It is also known a device for implementing the method of microwave diathermocoagulation of biological tissues, operating in the microwave range at a frequency of 2.4 GHz (see patent RU for invention No. 2318465), containing a radiator connected to a microwave generator. The latter is made in the form of a piece of coaxial line, which forms the working part and includes external and protruding internal conductors with insulation between them. At the end of the inner conductor, a metal tip made in the form of a hemisphere is attached to the base. The emitter is installed with a gap in the radio-transparent catheter. The working part is covered with a dielectric layer with a thickness equal to the thickness of the outer conductor of the coaxial line.

However, to ensure the operation of this device, it is necessary to inject 20-25% NaCl solution into pathological tissues with a volume equal to the volume of the destroyed tissue. The process of filling the pathological tissue with a solution can lead to its penetration into unaffected tissues. Operation of the device without the use of solution may lead to a breakdown with uncontrolled high-temperature processes. Heating of the pathological tissue occurs through heating the solution through the gradual spread of heat in the solution - the process of thermal action on the destroyed tissue is difficult to control.

Known coaxial emitter for microwave therapy of biological tissues (see RF patent for utility model No. 122581, IPC A61N 5/02, publ. 10.12.12).

The coaxial emitter is made in the form of a regular segment of a coaxial line, consisting of an inner and an outer conductor, as well as a dielectric filling between them, placed in a tightly fitting dielectric catheter, an inductive rod located at the end of a segment of the coaxial line in continuation of the inner conductor of the coaxial line, made with a diameter smaller diameter of the inner conductor of the coaxial line and placed in a cone made of dielectric material connected to the segment of the coaxial line by means of a dielectric washer, while at least two azimuthal slots are made in the outer conductor of the coaxial line.

Known device for electromagnetic therapy (patent RU for invention No. 2209096), containing an antenna assembly, a radiometric receiver, a pulse-width modulator, the output of which is connected to the input of a microwave generator, a square-wave generator, an indicator and a detector assembly. The antenna assembly is made in the form of a monopole vibrator, which is a miniature microwave radiator mounted on a needle holder, in which a puncture needle with a central conductor passing through a matching sleeve is fixed. The antenna unit is connected through a matcher connected to the output of the primary line of the reflectometer and the microwave amplifier, to the microwave generator. To the outputs of the arms of the secondary line of the reflectometer, the detector sections of the detector unit are connected, connected by the outputs through an analog divider to the controller. The latter is connected by an eight-bit bus to the matching device and includes a square-wave generator. The pulses are fed to the input of the pulse-width modulator and the input of the radiometric receiver. The output of the radiometric receiver is connected to the input of the radio thermometer with the possibility of transmitting signals to the controller and an indicator of the rate of temperature change. The keyboard is connected to the control input of the microwave generator.

However, in this device, the diameter of the dielectric matching junction in the form of a matching sleeve is much larger than the diameter of a monopole-vibrator antenna, which complicates the insertion and withdrawal of the device from pathological tissue. In addition, a burn of the treated tissue is possible due to imperfect control of the temperature inside the treated area, since both exposure and control are carried out in the same microwave range, although at different frequencies.

Known electrosurgical device for directing energy to a target volume of tissue, which contains a coaxial line having an inner conductor, an outer conductor, coaxially located around the inner conductor and a dielectric material located between them. An elongated electrically conductive member is located longitudinally at the distal end of the inner conductor. The balun structure is located on the outer conductor. A portion of the inner conductor and dielectric material of the coaxial line extends beyond the outer conductor at the distal end of the coaxial feed line. The electrically conductive element is electrically connected to the inner conductor. The electrosurgical device additionally contains an electromagnetic window configured to form a pattern of directional radiation during operation (see application for invention AU2010206119).

The design of a puncture antenna with a slot-type microwave radiator presented in the description has several significant disadvantages. The most important of them is a significant complication of the design of the microwave emitter, which prevents a decrease in the outer diameter of the puncture antenna, which is necessary for solving problems in microsurgery. A short list of the elements of this cumbersome structure is as follows: at the distal end of the inner conductor, a structure is connected, coaxially located on the outer conductor; moreover, it includes an electrically conductive cylinder coaxially located around the distal part and a dielectric structure located near the distal end of the electrically conductive cylinder, and the dielectric structure extends longitudinally from the distal end of the electrically conductive cylinder to the distal end of the electrically conductive element.

Closest to the proposed solution is a microwave device for the destruction of neoplasms and pathologically altered body tissues (see RF patent No. 2411019, IPC A61B 18/18, publ. 10.02.2011). The device is made in the form of a trocar made of a metal tube with a mandrel and a microwave waveguide, made coaxially extended inside and along the metal tube with the possibility of alternately inserting and removing them from it. On the distal side of the microwave waveguide there is a dielectric matching junction made of material with a smoothly increasing dielectric constant from 2 to 7 units and a monopole-dipole antenna. It has a glass-shaped section from the distal edge, the bottom facing outward from the distal end of the microwave waveguide, and with its open part towards the proximal end. At the proximal end of the microwave waveguide, there is a matching controlled module with coaxial-strip junctions connected to the microwave generator. The connection is made through a feeder with microwave connectors on both sides, corresponding to the mating parts of the microwave connectors of the matching controlled module and the microwave generator. The feeder, microwave waveguide, dielectric matching junction and monopole dipole antenna are completely filled with microwave dielectric. The walls and bottom of the monopole-vibrator antenna are made of metal; the bottom is ellipsoidal.

The disadvantages of this device are: an expensive technology for the implementation of a temperature tracking loop in the vicinity of the microwave emitter and the lack of opportunities to change its directional pattern.

The technical problem to be solved by the invention is the development of a device for the destruction of neoplasms that allows controlled heating in a given sector of the patient's body and excludes the possibility of interstitial burns of healthy tissues, mainly when irradiating neoplasms near the spinal canal of the spine.

The technical result of this invention is to form a sector radiation pattern while excluding microwave breakdown.

The claimed result is achieved by the fact that a microwave device for the destruction of pathologically altered body tissues, made in the form of a trocar from a metal tube with a microwave coaxial waveguide located inside the trocar tube with the possibility of insertion and removal from the tube, containing an outer shell made of medical steel, filled with fluoroplastic, and a central conductor located along the axis of the waveguide, including an electrically controlled matching device at the proximal end of the waveguide and a microwave connector for connecting to a microwave generator, according to the invention, additionally contains a power regulator in the form of a controller connected to the central conductor through decoupling from the microwave signal, the distal end the waveguide is equipped with a cone-shaped reflective tip made of medical steel with an acute angle at the top with a cavity inside, the inner walls of which are covered with a microwave dielectric, inside the cavity there is a continuation of the central conductor, the end of which is welded spot welding to the body of the tip, forming a thermocouple, at the distal end there is a slot emitter with an opening angle from 45 ° to 90 ° to form a sector radiation pattern, on the outer side of the waveguide a sliding foil holder is introduced to change the emitter parameters, with a length of at least the length of the slot ...

The claimed invention is illustrated by drawings.

Figure 1 shows a schematic representation of a microwave device as a whole; fig. 2 shows the design of a puncture coaxial waveguide antenna with a slot radiator and a radiation pattern along the slot; figure 3 is a section of a coaxial waveguide in the middle of a slotted radiator and its radiation pattern in the plane of the section; Fig. 4 is a radiation diagram of a slotted radiator at a frequency of 2.45 GHz, obtained by the authors of the application using a three-dimensional numerical model based on the finite element method.

In the drawings, the following designations are adopted by the positions:

1 - cylindrical cavity in the body of the reflector;

2 - area of welding of the central conductor with the reflector body;

3 - coaxial microwave connector;

4 - a trocar tube with a handle;

5 - fluoroplastic shell;

6 - comb on the central conductor in the area of the slot;

7 - slit antenna;

8 - the central conductor of the coaxial line;

9 - fluoroplastic shell;

10 - medical steel tube;

11 - sliding clip;

12 - reflector;

13 - feeder;

14 - coaxial strip transition;

15 - directional coupler with detector sections and electrically controlled matching module on strip lines;

16 - microwave generator with electrically controlled power;

17 - filter and a DC switch with a control pulse shaper;

18 - adapter of generator output power control signals;

19 - DC amplifier (DCA);

20 - reference generator and pulse width modulator;

21 - microcontroller;

22 - temperature indicator;

23 - directional diagram of the slot radiator;

24 - shielding shell of the coaxial waveguide.

A microwave device for the destruction of pathologically altered body tissues is made of a number of nodes and modules shown in FIG. 1-3. FIG. 4 The most important functional element of the device is a coaxial slit puncture microwave antenna, sealed with a fluoroplastic cover 5, made long coaxially inside and along the metal tube of the trocar 4 with the possibility of alternately inserting and removing it from the tube; the coaxial microwave waveguide with its proximal end faces the microwave coaxial connector 3 connected to the feeder, while the microwave waveguide consisting of the central conductor 8 of the coaxial line, fluoroplastic filling 9, placed in a tube 10 made of medical steel is made with the ability to transmit the microwave power up to 50 watts; its outer diameter is about 1.5-2.5 mm. On the distal side of the microwave waveguide there is a slotted antenna consisting of a two-humped plate in the form of a metal comb 6 on the central conductor in the area of the slot 7 and a cone-shaped reflector 12 made of medical steel. The scallop directs the main part of the microwave radiation deep into the biological tissue similar to a monopole vibrator. The central conductor of the coaxial line 8 is inserted all the way into the cylindrical cavity in the body of the reflector 1 and is spot welded to the bottom 2, and the inner cylindrical surface has a microwave dielectric coating. The length of the slit antenna 7 ranges from L ≈ 3λε / 2 to L ≈ 5λε / 8, where λε is the wavelength of microwave radiation in the biological tissue of the neoplasm. A sliding clip 11 made of medical steel is used for tuning to the operating frequency.

At the proximal end of the feeder 13 there is a microwave connector 3 connected to the output of the coaxial-strip junction 14 connected to the output of a directional coupler with detector sections as part of an electrically controlled matching module on strip lines and having a coaxial-strip junction 14 at the input. Junction 14 is connected to the output of the microwave generator 16, controlled by power, to the input of which the adapter 18 of signals for controlling the output power of the generator is connected, and its input is connected to the output of the pulse-width modulator of the module 20 and connected to the control output A of the microcontroller 21 at the input. The output of the reference generator of the module 20 is connected to the input In the microcontroller. The main stripline transmission channel of the module 15 through the choke is connected to the filter module and the DC switch with the control pulse generator 17. From its output, the temperature-dependent current is fed to the input of the constant current amplifier 19, the output of which is connected to the input T of the microcontroller 21, and from its output the digital temperature code is fed to the input of the temperature indicator.

The claimed device has a set of three coaxially slotted puncture microwave antennas shown in Fig. 2 and operating at the permitted frequencies in medicine 0.915 GHz; 2.45 GHz and 24.1 GHz. It is possible to select a specific puncture slotted microwave antenna for various types of pathology with adjusting the length of the slotted radiator section.

The claimed device operates as follows.

For effective use of the proposed microwave device in a surgical treatment before surgery, a test control of the equipment readiness is carried out. For this, the puncture slotted microwave antenna with the required operating frequency is removed from the sterile package. Connect it to the module 15 (directional coupler with detector sections and an electrically controlled matching module on strip lines) by means of a feeder 13 and a coaxial strip junction 14 with microwave connectors 3. Place the puncture slot microwave antenna Fig. 2 into a sterile test tube with saline or water for injection and turn on the microwave generator 16 through the control panel P of the microcontroller 21 for a predetermined processing time of the pathological tissue. Using the temperature sensor 2, the indicator 22 controls the temperature of heating the water in the test tube. Provided that the temperature values corresponding to those planned in the process of the upcoming treatment of pathological tissue (and obtained earlier by calculation and empirically worked out) are obtained, the operation of the equipment prepared for the upcoming medical surgical manipulation is considered. This test control takes 2-3 minutes.

The patient is placed on the operating table in the most convenient position for the planned surgical procedures. The exact location, size and shape of the pathological tissue are determined using ultrasound, X-ray or computed tomography, and previously obtained data are checked. Taking into account all the information received, the safest place of the planned puncture and introduction of the trocar 4 containing the puncture slotted microwave antenna is selected. 2.

Then they proceed to surgical manipulation - destruction of a neoplasm or processing of pathological tissue. To do this, under local anesthesia under the control of X-ray or ultrasound equipment, the careful introduction of trocar 4 into the central or border area of the neoplasm or pathological tissue is carried out. The desired position of the slit emitter 7 is monitored by visualizing the ridge 6 coinciding with the axis of the sector radiation pattern emerging from the slit. They begin the procedure for the destruction of a neoplasm or pathologically altered tissue, providing their microwave treatment in the stated modes: temperature ranges of 44-48 ° C, with a radiation power of up to 50 W, at operating frequencies of 0.915 GHz permitted in medicine; 2.45 GHz and 24.1 GHz, within an exposure duration of about 3-120 seconds. During the entire pathology treatment procedure, the accuracy of the localization of the emitter is monitored using visualization tools - X-ray, computed tomography, MRI tomography, and ultrasound equipment. Simultaneously, the temperature dynamics of the irradiated tissue is monitored by thermocouple 2, and from the very beginning of the treatment process to the end, it is not allowed to go beyond the established temperature regime. When processing pathologically altered soft tissues, they provide lower temperatures of the order of 44-46 ° C, preventing higher processing temperatures, in contrast to the temperatures used for processing bone and cartilaginous tissues.

To analyze the electromagnetic field in the near zone of the antenna emitter, a three-dimensional numerical model of a coaxial emitter with a longitudinal slit and an adjacent biological tissue volume with specified dimensions and electrophysical properties of antenna structural materials and dielectric parameters of biological tissue for a frequency range of 1 ... 10 GHz was built. The model was based on the homogeneous Helmholtz equation with the Neumann and Dirichlet boundary conditions on metal elements of the antenna structure, the condition for the continuity of the tangential field components at the interface between the media, and the condition for the scattering of electromagnetic waves at a distance from the antenna. To solve the boundary value problem of electrodynamics, the finite element method with tetrahedral functions of the Whitney form of the first order was used. The results of numerical analysis fully confirmed the possibility of the formation of zones of heating of biological tissue, as shown in Fig. 4.

Example.

The microwave device has been tested on sick animals, as well as on diseased postoperative human tissues. The parameters of the microwave effect of the proposed device (temperature, time, power) on the tumor tissue were experimentally determined in vitro. For this, blocks of tumor tissues were used, which were delivered from the operating room within the first two hours after their removal from the patient's body (malignant and benign tumors of internal organs, musculoskeletal and adipose tissues). Efficacy and safety were tested experimentally in vivo in animals (rabbits, rats). The volumes of destructive microwave exposure to tissues were determined after the animals were euthanized, and the temperature exposure zone was monitored during the operation with IR thermographs with fiber-optic sensors directly in the area of pathological tissue and in located unaffected tissues.

The obtained research results showed that with the help of the inventive device under microwave action by a slit emitter, destruction of pathologically altered tissues in the area of the sector diagram of radiation is achieved without affecting the surrounding unaffected tissues.

Claims (2)

1. A microwave device for the destruction of pathologically altered body tissues, made in the form of a trocar made of a metal tube with a microwave coaxial waveguide located inside the trocar tube with the possibility of insertion and removal from the tube, containing an outer sheath made of medical steel, filled with fluoroplastic, and a central conductor, located along the axis of the waveguide, including an electrically controlled matching device at the proximal end of the waveguide and a microwave connector for connecting to a microwave generator, characterized in that it additionally contains a power regulator in the form of a microcontroller connected to the central conductor through decoupling from the microwave signal, the distal end of the waveguide is equipped with a reflective a cone-shaped tip made of medical steel with an acute angle at the apex with a cavity inside, the inner walls of which are covered with a microwave dielectric, a continuation of the central conductor is located inside the cavity, the end of which is spot-welded to the body. and, forming a thermocouple, a slot emitter with an opening angle of 45-90 ° is located at the distal end to form a sector radiation pattern, a sliding foil holder is introduced on the outer side of the waveguide to change the emitter parameters, with a length not less than the slot length. 2. The microwave device according to claim 1, characterized in that a comb is made on the central conductor in the area of the slot, which is a metal plate with a double-humped profile, welded to the central conductor of the coaxial antenna in the center of the slot.

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