RU2368406C2 - Method and device for destroying malignant tumours - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions refers to medicine and is meant for destroying malignant tumours. Local interstitial thermoradiotherapy is performed. The working needle electrode is introduced into the tumour centre and radio-frequency energy is supplied to it during the heating period. At that, energy of microwave range id used. The device includes a generator connected to the working needle electrode. Generator of microwave range is used as generator. The working needle electrode is connected with flexible radio-frequency cable to the generator. A piece of rigid coaxial line with the central conductor protruding by 5-15 mm is used as the working needle electrode.

EFFECT: proposed group of inventions allows achieving deeper penetration into the tissue, thus providing destruction of the whole volume of tumopur; absence of the second electrode allows excluding passage of undesirable currents through the patient's body and their pathologic influence on the organism.

7 cl, 2 dwg

Description

The invention relates to medicine and medical equipment, namely to local interstitial hyperthermia, and can be used to destroy malignant neoplasms.

Worldwide, approximately two million people develop liver cancer each year. Only 30% of patients can undergo radical surgical treatment. Therefore, the development of new treatment methods for inoperable patients, in particular with liver tumors, is very relevant.

One of the most successful and dynamically developing areas of oncology is the method of local thermoradiotherapy. The method is very effective (comparable in effectiveness to surgery), minimally invasive.

Known methods of local hyperthermia, based on the introduction into the tumor of various ferromagnetic or conductive fluids, followed by heating the RF current to 44 ° C and above (See Prof. I. Karev "Hyperthermic methods in oncology", www.k-test. com / index). Experimental and clinical studies on the use of ferromagnetic fluids have shown their negative properties. The adverse effects of the use of ferromagnetic suspensions are often developing skin burns and cosmetic defects in the postoperative scar. The results of morphological studies (for example, breast cancer) indicate that the use of thermal modifiers causes pronounced structural changes in malignant tumors: the density of the viable parenchyma decreases, the index of mitotic activity and the number of normal mitoses decrease.

Also known is a method and device for the treatment of malignant neoplasms (see RF patent No. 2063255, A61N 5 | 02, A61B 17/36, 1996), based on the use of conductive fluid, followed by heating with an RF current.

The device comprises a high-frequency generator, emitters, a temperature measurement and control unit connected to temperature sensors. A high-frequency energy distributor is installed between the high-frequency generator and emitters. Each emitter is made in the form of a group of electrodes consisting of at least three needles, while the high-frequency energy distributor contains at least three coupling coils, each of which is connected to one needle-electrode from the group by the first output and through a variable resistance with other needle-electrodes from the group.

The treatment method is as follows. Previously, after the introduction of anesthetics, high molecular weight dextran is peritumorally administered. The heating zone is conditionally anatomically divided into several sectors, in each of which a group of electrodes is introduced, of at least three needles. They reach a temperature of 49 ° C near the needles in less than 1 min and then evenly warm the neoplasm to 49 ° C, applying high-frequency energy of the corresponding magnitude from each individual electrode group depending on the conductivity of the sectors. The device uses a generator with an output power of 50 W, operating at a frequency of 13.56 MHz. Heating of the individual parts of the neoplasm to a temperature of 49 ° C is carried out in no more than 1 min, which allows you to quickly go through the border of 39-40 ° C for the entire mass of the neoplasm, in which cancer cells begin to spread rapidly with blood flow. The introduction of conductive fluid, namely dextran, leads to compression of the blood vessels. This makes it difficult to carry cancer cells with blood flow to healthy tissues. Maintaining a temperature of 49 ° C in a malignant neoplasm is carried out for at least 90 minutes, which allows to achieve a more pronounced therapeutic effect, which ensures almost complete cancer cell devitalization.

A disadvantage of the known device is a complex electrode system, which complicates the device and makes it bulky. The device includes resonant circuits directly connected to the needle-electrodes inserted into the neoplasm. A change in the electrical characteristics of the tissue during the heating procedure leads to a change in the matching of the high-frequency generator with the load. And, as a result, manual adjustment of the contours is necessary during the work, and in the presence of multiple small focal organ lesions (metastases), working with this device looks difficult.

The disadvantage of this method is the long treatment time of the tumor - more than 90 minutes, which limits the application of the method for surgical interventions. In addition, the introduction of dextran around the neoplasm to create good conductivity is contrary to the principles of ablasticity (possibly secondary infection of healthy tissue with cancer cells). Due to the leakage of heated liquid to adjacent organs, thermal ablation of the latter is possible. In addition, it is quite difficult to ensure uniformity and uniformity of filling with dextran. The unevenness and heterogeneity of filling with dextran leads to inhomogeneous heating of the tumor, and, as a consequence, the low efficiency of the method.

Closest to the invention is the universal complex "METATOM-2" for the thermal destruction of tumors (link taken from the Internet, http://medprom.ru/medprom/237250). The device includes a high-frequency generator, a syringe pump, a control unit, as well as a set of disposable disposable accessories, including a neutral electrode, a working needle electrode and a temperature sensor. The working needle electrode has an insulating coating along the entire length, with the exception of the end with a length of 15-20 mm with holes for supplying an isotonic sodium chloride solution to the heating region. The temperature sensor is made in the form of an uncooled needle electrode with an insulating coating along the entire length. During the implementation of the method, a neutral electrode is placed under the patient’s body, a working electrode is introduced into the center of the tumor, and radio frequency energy is supplied to it. When a high-frequency current passes between the non-insulated end of the needle electrode and the neutral electrode, the tissue near the end of the needle electrode heats up to a temperature of 50-100 ° C, causing the death of tumor cells. At the same time, an isotonic solution enters the heating region through the holes at the end of the needle electrode, which helps to reduce tissue drying near the end of the needle electrode and increase the size of the area of thermal tissue necrosis. The size of the coagulation region depends on the magnitude of the high-frequency power, the heating time, the rate of introduction of the isotonic solution, as well as the configuration of the tip of the needle electrode.

The disadvantage of the complex "METATOM-2" and the method of destruction of tumors is the long heating time (tens of minutes), which limits its use in surgical interventions. Due to the fact that high-frequency currents pass between the neutral and needle electrodes through the patient’s body (the system is a two-electrode), and the input power varies from 50 to 300 W, tissue heating along the current path is not controlled, and the pathological effect on the body is not evaluated. Therefore, the use of the complex for patients with implanted pacemakers is limited. In addition, a significant drawback of the complex is the work at the lower boundary of the high-frequency range (hundreds of kilohertz). In this case, when the current flows from the needle working electrode to the neutral electrode, the surrounding tissues dry out, as a result of which the conductivity drops, which leads to a decrease in the absorption of the heating power and, consequently, to a decrease in the efficiency of the method. To restore conductivity, a physiological solution must be injected into the affected area, which complicates the design of the working needle electrode and the complex as a whole.

The problem to which the invention is directed, is to create a method and a device that implements it, providing closed (percutaneous) and open (during surgical operations) accesses with a short heating time, effective destruction of a malignant tumor and its metastases in parenchymal organs, in particular in the liver. Another objective of the present invention is the creation of an inexpensive, simple in design domestic device that provides an affordable way to treat a wide range of patients.

The problem is solved in that in the method of destruction of malignant tumors by conducting local interstitial thermoradiotherapy, which includes introducing a working needle electrode into the center of the tumor and applying radio frequency energy to it during the heating time, the microwave energy is used according to the invention, and the working needle electrode is used a piece of a rigid coaxial line with a central conductor protruding by 5-15 mm.

The method preferably uses energy in the range of 1-5 GHz with an adjustable output power in the range of 10-500 W, and the heating time is 5-30 s.

The problem is also solved by the fact that in the device for the destruction of malignant tumors, including a generator connected to a working needle electrode, according to the invention, a microwave generator is used as a generator, and the working needle electrode is made in the form of a segment of a rigid coaxial line with a protruding 5-15 mm central conductor connected by a flexible coaxial line to the generator. The generator has a frequency range of 1-5 GHz and is made with adjustable output power in the range of 10-500 watts. A magnetron can be used as a microwave generator.

A segment of a rigid coaxial line according to the invention comprises a central conductor made of refractory metal, such as titanium or molybdenum, and an external conductor placed in a thermal shield made of metal, such as stainless steel, the central and outer conductors are separated by a ceramic insulating tube.

The essence of the proposed invention lies in the fact that to ensure the effective destruction of malignant tumors with a short heating time, the authors proposed a group of inventions united by a single inventive concept - a method and device using microwave energy. The ease with which microwave energy is converted into heat makes it possible to obtain very high heating rates, without damaging electrical loads in the tissues. It is known (microwave energy, volume No. 2, Moscow: Mir publishing house, 1971, 53 pp.) That with increasing frequency the absorbed power per unit volume increases, which is determined by the formula

,

,

where f is the frequency in megahertz, E is the electric field strength in V / cm, s is the dielectric loss factor of the substance, and P is the absorbed power.

Applicants are aware of the use of microwave energy in remote local hyperthermia (see Prof. Karev ID "Hyperthermic methods in oncology", www.k-test.ru/index), which undergo surface-located tumors (tumors of the skin, lower lip , breast, lower ampulla of the rectum, prostate), because the depth of optimal heating is usually not more than 4-5 cm. Known technical solutions for remote local hyperthermia are not applicable for local interstitial hyperthermia.

The use of microwave energy in local thermoradiotherapy allows for effective destruction of malignant tumors to reduce the heating time to 5-30 s (unlike the prototype, where the heating time is 30-40 minutes), which is especially important during surgical operations. The experiments conducted by the authors revealed the preferred frequency range - 1-5 GHz with an adjustable output power of 10-500 W, since the size of the coagulation region depends on the magnitude of the high-frequency power and heating time.

The microwave energy is supplied using a working needle electrode made in the form of a segment of a rigid coaxial line, which simplifies the design of the electrode and the device as a whole and distinguishes the proposed technical solution from the prototype. The METATOM-2 complex used a two-electrode system with a working needle electrode, which had openings at the end through which an isotonic solution was supplied to prevent drying of the tissue and restoration of its conductivity. In the proposed technical solution, there is no need to prevent drying, since in the process of heating and reducing the amount of absorbing liquid in the exposure zone (due to the high temperature) in contact with the working part of the electrode, the absorption of microwave energy drops sharply. In this case, the near field penetrates deeper into the tissue, ensuring the destruction of the entire tumor volume. The absence of a second electrode eliminates the passage of unwanted currents through the patient’s body and their pathological effect on the body.

The experiments carried out by the authors revealed the preferred dimensions of a segment of a rigid coaxial line. The local effect on biological tissue is determined by the geometric dimensions of the central conductor protruding by 5-15 mm.

The implementation of the microwave generator in the form of a magnetron made it possible to create an inexpensive, simple in design domestic device that provides an affordable way to treat a wide range of patients.

The invention is further explained using the drawings, where:

figure 1 presents a block diagram of a device for the destruction of malignant neoplasms; figure 2 presents the working needle electrode.

The device (see figure 1) contains a microwave generator 1 with adjustable output power, a working needle electrode 2 connected through a flexible coaxial line 3 and connectors 4 to the generator 1. The microwave generator 1 is made in the form of a magnetron with a preferred operating range of 1-5 GHz and adjustable output power of 10-500 watts.

The working needle electrode 2 (see figure 2) is made in the form of a segment of a rigid coaxial line with a diameter of 2-3 mm, a length of 150-250 mm and contains a Central conductor 5, protruding 5-15 mm from the surrounding ceramic tube 6. Central conductor 5 is placed inside the external electrode 7, which, in turn, is placed in a protective thermo screen 8. The central conductor 5 can be made of refractory metals of titanium or molybdenum, the external electrode 7 and the thermo screen 8 can be made in the form of stainless steel tubes.

The treatment method is as follows. Using known methods, a malignant neoplasm is diagnosed. Depending on the size of the tumor, the presence of metastases, the operating parameters of the generator 1 — frequency and power — are set and a needle working electrode 2 with a protruding central conductor 5, the dimensions of which must correspond to the size of the tumor, is connected through a flexible coaxial line 3 and connectors 4. Then, a closed (percutaneous) or open (during a surgical operation) method, a needle working electrode 2 is introduced into the center of the tumor. Then, microwave energy is supplied to the working electrode 2. In this case, local heating of the biological tissue occurs due to the absorption of microwave power. Heating starts immediately, the temperature rises above 100 ° C. Electromagnetic currents exist only near the end of the working electrode. By changing the input power from 10 to 500 W and the processing time from 5 to 30 s, you can adjust the temperature and depth (area) of the tissue processing.

Preliminary in vitro tests have been carried out on viable affected organs, mainly the kidneys and liver. Visually, it was possible to observe the process of intense thermocoagulation of metastases and the primary tumor, occurring for short periods of time. To accurately determine the boundaries of tumor necrosis and pathomorphological changes in areas adjacent to the exposure zone, histological studies were performed. Histological analysis confirmed necrosis of the tumor and adjacent tissues. Experiments were carried out depending on the input power, processing time and use of working electrodes with different lengths of the protruding central conductor, followed by histological analysis. Studies were also conducted on the area of thermal damage to tumor tissue depending on the neoplasm.

The experiments showed that the proposed method and device can quickly and effectively carry out the destruction of a malignant tumor, including during surgery, which opens up great opportunities for its use in surgical practice. One of these possibilities is carrying out organ-preserving operations. For example, in the case of multiple small focal lesions of the organ, when destroying metastases by the proposed method, the organ can not be removed. Also, during surgery, it is not always possible to provide access to the neoplasm without damaging nearby vessels and organs. This problem can also be solved by the proposed invention. In surgical practice, there are cases when it is impossible to remove the affected organ according to the local process or the volume of the operation will exceed the compensatory capabilities of the body. Using the proposed invention allows for the processing of tumors.

Claims (7)

1. A method of destroying malignant tumors by conducting local interstitial thermoradiotherapy, comprising introducing a working needle electrode into the center of the tumor and applying radio frequency energy to it during the heating time, characterized in that the microwave energy is used, a piece of hard coaxial line is used as the working needle electrode. with a central conductor protruding by 5-15 mm. 2. The method according to claim 1, characterized in that preferably use the energy of the range 1-5 GHz with adjustable output power in the range of 10-500 watts. 3. The method according to claim 1 or 2, characterized in that the heating time is 5-30 s. 4. A device for the destruction of malignant tumors, including a generator connected to a working needle electrode, characterized in that the microwave generator is used as a generator, and the working needle electrode is made in the form of a piece of a hard coaxial line with a central conductor protruding by 5-15 mm, connected by a flexible radio frequency cable to the generator. 5. The device according to claim 4, characterized in that the generator has a frequency range of 1-5 GHz and is made with adjustable output power in the range of 10-500 watts. 6. The device according to any claims 4 and 5, characterized in that a magnetron is used as a microwave generator. 7. The device according to any one of claims 4. and 5, characterized in that the section of the hard coxial line contains a central conductor made of refractory metal, such as titanium or molybdenum, and an external conductor placed in a thermo screen made of metal, such as stainless steel, the central and external conductors are separated by an insulating ceramic tube .

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