RU201356U1 - RADIO FREQUENCY SYSTEM FOR LOCAL THERMAL DESTRUCTION OF SURFACE TUMORS - Google Patents

Abstract

The utility model relates to medical technology and can be used to destroy pathologically altered tissues of the human and animal body. The tumor ablation device contains a high-frequency generator, active needle electrodes and a passive electrode connected to the generator. The active electrodes are arranged in a circle and are fixedly fixed in a housing having a rod displacement mechanism, on which a passive electrode is fixed with holes, the number of which corresponds to the number of active electrodes, and which can be moved in the axial direction relative to the active electrodes. The diameter of holes for active electrodes should not exceed 0.125 D, and the diameter of attachment of active electrodes is D / 2, where D is the desired zone of tumor necrosis. The technical result consists in the emergence of the possibility of heating flat neoplasms by improving the passive electrode and eliminating its overheating. 1 wp cl, 4 dwg

Description

The utility model relates to the field of medicine and veterinary medicine, mainly to surgery, and can be used to destroy pathologically altered tissues of the human and animal body. A relatively recent, minimally invasive method of thermal ablation of tumors is based on heating them to the temperatures of coagulation and necrosis with subsequent replacement of the tumor with fibrous tissue. Such heating can be carried out by electromagnetic fields in the radio frequency and microwave ranges. Currently in oncology, the most developed radiofrequency method of destruction (ablation) of biological tissues. High-frequency energy from the generator (1) is supplied to the center of the tumor (2) using a thin needle electrode (3), covered with a layer of insulation over the entire surface, except for the working end 1-3 cm long. (Dolgushin B.I., Kosyrev V.Yu. Radiofrequency thermoablation of tumors, Ed. By MI Davydov - Moscow: Practical Medicine, 2015 - 192 p.). Biotissue heating is carried out due to ohmic losses when current flows from the working end of the active electrode located in the biological tissue to a large-area passive electrode 4 located on the patient's body surface (Fig. 1a). The much more intense heat generation required for ablation in the affected area is provided by the use of an active electrode with a surface many times smaller than the surface of the second passive electrode. Accordingly, the current density increases at the point where the active electrode touches the body tissues, which determines the desired effect. When using this technology on tumors of larger diameter, problems arise associated with a sharp decrease in the heating temperature of the tumor with distance from the active electrode. Therefore, the maximum diameter of the necrosis zone in the cross section reaches 1.5-2.0 cm and depends on the level of the supplied power, heating time and the type of heated biological tissue. The size of the ablation area is also limited by the rapid drying of the tissue at the point of contact of the working part of the electrode with the tissue, which causes a sharp increase in resistance in the circuit between the needle and passive electrodes. In this regard, attempts have been made to increase the heating regions by cooling the active electrode, "splitting" a single electrode into several electrodes, etc. (Makarov V.N. Hardware and electrode support of foreign and domestic installations for radiofrequency ablation // 19th scientific and technical conference "Medical and technical technologies guarding health" MEDTECH-2017. Proceedings. Research Institute of Radiology named after N.E. Bauman, Moscow, 2017 - pp. 91 - 100).

Recently, due to the development of a variety of treatment methods that apply a current of relatively high frequency for a long period of time, a problem has arisen associated with an increased risk of burns on the passive electrode. It is also worth noting that due to physical conditions, maximum heating occurs at the edge areas, so the risk of burns is especially high in these edge areas. The same amount of heat is generated on the passive electrode as on the active electrode, so its area must be many times larger than the area of the active electrode for this heat to be dissipated over a larger area. Increasing the scattering power of the passive electrode is one of the main problems in monopolar surgery. In order to reduce the heating of the passive electrode, various cooling methods are used by increasing their scattering ability by increasing their size. If there are restrictions on the transverse dimensions of the electrode, cells with materials that have phase transitions in the temperature range not exceeding a certain value are placed on the outer surface of the passive electrode (Swanson DK Fleischman SD Systems and methods for creating long, thin lesions in body tissue // US Patent No. 6447506 B1. 10.09.2002).

In all cases, spherical tumors are the subject of application of HF fields during monopolar heating. The classical design allows you to successfully heat tumors of this shape, but it is completely unsuitable for heating flat tumors located on the surface of the skin and reaching 6.0-8.0 cm in diameter (Gantsev Sh. X. Oncology: Textbook for medical students / M .: LLC "Medical Information Agency", 2006. - 488 p.).

The closest to the proposed one is the installation for radiofrequency ablation (Patent 58905. RF, IPC A61B 18/00. Installation for destruction of biological tissues (options): No. 2006112554/22: application. 17.04.2006: publ. 10.12.2006 / V.N. Makarov, Yu.A. Khitrov, A.A. Bobrov - 12 p.) Including a radio frequency generator, a control unit, a pump and a radiator of two electrodes, one of which has a large area and is attached to the patient's body, and the other is made in the form of an inserted into the destructible tissue of a hollow metal needle with a built-in thermal sensor, coated with a dielectric with removed insulation on the working part of the needle end, which are connected to the generator. The main disadvantage of this device is the impossibility of heating flat tumors and the likelihood of burns at the site of contact with the passive electrode.

The objective of the proposed utility model is to eliminate these disadvantages: the use of the power that is simply dissipated in the surrounding space in classical versions of monopolar ablation of tumors to heat flat tumors and exclude overheating by maintaining a given temperature at the point of contact of the passive electrode with the tissue.

For this, in a known embodiment of a system for ablation of tumors, containing a generator, needle active and flat passive electrodes connected to the generator (1), a passive electrode (4) with a hole (5) is applied to a flat tumor (2) through which a needle electrode (3). As a result, the energy released at the passive electrode can be used for additional heating of the biological tissue surface in contact with the passive electrode (Fig. 1b). Thus, a passive electrode in such a design turns into an additional active electrode, and the resulting system of two bipolar electrodes of different sizes allows heating flat neoplasms on the skin of patients, which is unattainable in the case of using classical monopolar systems. In addition to such a single-electrode structure, it is possible to design a multi-electrode system of two or more single-electrode systems shown in Fig. 1b. In Fig. 1c, active electrodes (3) and a passive electrode (4) with holes (5), the number of which is equal to the number of active electrodes, are connected to the generator (1) inserted into the tumor (2). The passive electrode has the ability to move in the axial direction relative to the active electrodes providing a different heating thickness. To prevent overheating of the passive electrode, a temperature control and regulation system can be added to the design (6).

The technical result provided by such a design consists in the possibility of heating flat neoplasms by improving the passive electrode and eliminating its overheating.

The essence of the device is illustrated in figure 2, which shows one of the possible designs of a device for ablation of flat tumors.

The device consists of a generator (7) and 4 needle active electrodes (8) connected to it, fixed in the body (9) of the device. The passive electrode (10) has 4 holes, made coaxially, and intended for the introduction of active electrodes. The passive electrode is fixed on the rod (11) and can be moved in the axial direction relative to the active electrodes, making it possible to change the depth of immersion of the active electrodes into the tumor. A thermocouple is inserted into the passive electrode, which makes it possible to measure the temperature in the center of the passive electrode and maintain this temperature at a given level using a control device (12). The appearance of such a device with six electrodes is shown in Fig. 3. It has been experimentally established that to obtain the desired zone of necrosis with a diameter D, the holes should be located at the diameter D / 2, and their diameter should be no more than 0.125D. The number of holes can vary from one to six, depending on the size of the tumor. When installing the device on a flat tumor and applying a high-frequency voltage to the electrodes on a simulator of a biological object (potatoes), heating patterns were obtained (Figs. 4 a and b), indicating the possibility of obtaining a thermal field with dimensions up to 60 mm in diameter and up to 20 mm deep. The application of such a simulator is described in more detail in the article Thermal imaging study of the temperature field in bipolar multi-electrode ablation / Makarov V.N., Makhov M.A., Miroshnik V.I., Shmeleva D.V., Kuchin K.O. // Biomedical radio electronics. - 2019. - No. 2. - from 5-14.

Medical research of experimental devices was carried out in the oncology clinic of Sechenov University during operations on the head and neck. The results of operations indicate the effectiveness of the use of such devices in the ablation of flat tumors.

Claims (2)

1. A radio-frequency device for local thermal destruction of superficial tumors, containing a high-frequency generator, active needle electrodes and a passive electrode connected to the specified generator, characterized in that the active electrodes are arranged in a circle and are fixed in a housing having a mechanism for moving the rod, on which a passive electrode with holes, the number of which corresponds to the number of active electrodes, and which can be moved in the axial direction relative to the active electrodes, and the diameter of the holes for the active electrodes does not exceed 0.125 D, and the diameter of the attachment of the active electrodes is D / 2, where D is the desired zone of necrosis tumors. 2. The radio frequency device according to claim 1, characterized in that it comprises means for monitoring and maintaining the temperature on the passive electrode.

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