V.N. Makarov – Dr.Sc. (Phys.-Math.), Professor, Department of Bio-Cybernetic Systems and Technologies,  MIREA – Russian Technological University (Moscow)

E-mail: makarov_vn@bk.ru

V.I. Miroshnik – Head of Department, Company TECHNOSVET (Moscow)

E-mail: technosvet@bk.ru

M.A. Makhov – Deputy director, Company TECHNOSVET (Moscow)

E-mail: technosvet@bk.ru

N.A. Boos – Undergraduate, Department of Bio-Cybernetic Systems and Technologies, 

MIREA – Russian University of Technology (Moscow)

E-mail: 111llkmbc@mail.ru

Development of interventional radiology and latest developments in the field of high technology have made it possible to create a number of technological areas that ensure the effective conduct of tumor destruction: ultrasound, laser, radiofrequency, microwave, cryosurgical. At the same time, the method of radiofrequency thermal ablation (thermal destruction) of tissues with coagulation temperatures (50…60ºС and above) has firmly taken one of the leading positions among these technologies of local destruction due to relative cheapness and affordability.

Most of RFA units use monopolar or bipolar modes to heat spherical or ellipsoidal tumors.

These connection schemes are completely unsuitable for heating superficial tumors that have the shape of a round cylinder. The thermal field for the destruction of such tumors should have the shape of a round straight cylinder, and this field should overlap the largest diameter of the tumor and its height.

A design has been developed for ablation of planar tumors, in which a flat electrode is located on the surface of the ablation zone, and needle electrodes are introduced into the coagulation zone through holes in the flat electrode to a depth equal to the height of the region. The number of holes varies depending on the number of needle electrodes. As a result, the energy released on the passive electrode is used to additionally heat the surface of the biological tissue in contact with the passive electrode. The resulting system of two bipolar electrodes of different sizes allows the heating of flat tumors on the skin of patients, which is unattainable in case of using classic monopolar and bipolar systems.

Experimental studies of the developed systems were carried out on the "METATOM-3" system, allowing you to connect from 1 to 8 electrodes of various sizes. Potato was used as a load simulator, which allows one to preserve the shape and dimensions of the heat field after heating. The temperature of the introduced electrodes, the impedance, and the current power in real time were recorded on the monitor screen. The heating process was terminated upon reaching a temperature of 60 ° C in the center of the flat electrode. Studies conducted on a simulator of human biological tissue have shown that it is possible to provide heating zones up to 60 mm in diameter and 20 mm deep. To obtain the desired necrosis zone with a diameter of D, the holes should be located on a diameter of D/2, and their diameter should be no more than 0.125D. The number of holes varies from one to six, depending on the number of electrodes.

Clinical trials have confirmed the effectiveness of the new system for ablation of superficial tumors. Implementation of the developed system gives an opportunity to solve the problem of superficial tumors therapy.

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