Principle Radiofrequency is a high frequency vibration with a frequency of 150,000 times per second. The human body is a complex structure composed of many organic and inorganic substances, and body fluids contain a large number of dielectrics, such as ions, water, colloidal particles, etc. The human body mainly relies on ion movement to conduct current. Under the action of high-frequency alternating current, the direction of ion concentration change with the direction of the current for positive and negative half round-trip changes. Under the high frequency oscillation, the ions between the two electrodes along the power line direction of rapid movement, from the mobile state gradually changed to vibration state. Due to the different size, mass, charge and movement speed of various ions, the ions rub against each other and collide with other particles to produce bio-thermal effect. Due to the poor heat dissipation of tumor, the temperature of tumor tissue is higher than its neighboring normal tissues, and cancer cells are sensitive to high heat, high heat can kill cancer cells without side effects. Thermal effect The therapeutic mechanism of RF therapy instrument with ablation and cutting function is mainly thermal effect. RF waves are essentially electromagnetic waves in a specific range. Most of the current medical radiofrequency adopts the frequency of 200KHz – 750KHz. When the radio frequency current flows through the human tissue, the rapid change of electromagnetic field makes the positive and negative ions in the cell move rapidly, so the friction between them and other molecules and ions in the cell makes the lesion site warm up, resulting in the evaporation of water inside and outside the cell, drying, solidification and shedding to sterile necrosis, so as to achieve the purpose of treatment. The treatment process of radiofrequency ablation Under local anesthesia or intravenous anesthesia, radiofrequency generated by radiofrequency generator is emitted to the center of solid tumor under the guidance of B-ultrasound or CT to heat up the tumor to 60℃ or above, and finally dehydration, coagulation, denaturation and necrosis are gradually absorbed and discharged by the body to eliminate solid tumor without surgery. Radiofrequency bio-thermal effect causes the following effects on solid tumor 1) death of tumor cells; 2) vascular damage and blockage of blood supply; 3) destruction of nerves in tumor; 4) decrease of pH value; 5) destruction of hormone receptors; 6) activation of immune system especially phagocytic system, and finally the tumor shrinks and disappears by itself. Multi-stage radiofrequency tumor ablation is a new technology of minimally invasive treatment for solid tumors emerging in recent years, which can save patients from the pain of open surgery and has the advantages of high efficacy, less trauma, less pain, faster recovery, no sequelae, no risk and wide indications compared with traditional treatment, which is hailed as green treatment technology by domestic and foreign experts. Tumor cells are less tolerant to heat than normal cells. Local heating to 39-40℃ can stop cancer cells from dividing, and 41-42℃ can cause cancer cells to die or cause DNA damage, and irreversible cell damage occurs above 49℃. Cluster electrode RF electrode emits high frequency RF waves to excite tissue cells to perform plasma oscillation, and the heat generated can make local temperature reach over 90℃, thus killing tumor cells quickly and effectively. The principle of this technology is that under the guidance of CT and color ultrasound, the multi-polar needle ablation electrode is accurately pierced into the tumor site, and the RF ablation instrument conducts the RF pulse energy into the tumor tissue through the multi-polar needle under the control of electronic computer, so that the tumor tissue generates local high temperature (70 ℃ -95 ℃) to achieve the purpose of coagulation and necrosis of the tumor tissue and its adjacent tissues that may be spread, and the necrotic tissue is mechanized or absorbed in situ. The necrotic tissue is mechanized or absorbed in situ. Indications Radiofrequency ablation can be used for benign and malignant solid tumors of human organs, and currently it is more clinically used for: liver cancer, lung cancer, breast cancer. Patients with primary tumors, metastatic tumors, advanced tumors that cannot be surgically removed, tumors found to be incompletely removed by exploration during surgery, and tumors that cannot tolerate radiotherapy and chemotherapy can all receive radiofrequency ablation treatment. The treatment process is simple. The treatment is carried out under local anesthesia, and the treatment time is about 1-2 hours. Patients can listen to music and watch TV while receiving tumor ablation treatment, which has a high safety factor and is less expensive, less painful and faster recovery than traditional tumor treatment methods. Combined with chemotherapy or radiotherapy, it can achieve the purpose of prolonging patients’ life, improving life quality and reducing patients’ pain. History of the development of radiofrequency ablation Radiofrequency ablation has a long history of development, so the technology has also undergone continuous improvement and maturation, with exact efficacy. The effective ablation range of single pole is small, and the effect is poor for large tumors, so there is now the cluster multi-pole needle. It has been proved that if a tumor of 7cm in diameter is treated with a 4cm diameter spherical destructive foci, 22 points are needed for complete coverage (difficult to operate in practice). With a 5 cm diameter spherical destructive foci, 12 points are also required. To address this situation, RITA USA has developed a series of RF needles for tumors of different sizes. The first generation of umbrella-shaped multi-pole needle or monopole needle can be selected for tumors below 3cm in diameter, but due to the influence of temperature conduction, the size of various monopole needle destruction foci is small (as shown below), and the destruction of larger tumors above 3cm will not be complete. For tumors with a diameter of 3cm to 5cm, the second-generation multi-polar needle developed by RITA is suitable for all tumors under 5cm, with a maximum ablation diameter of 5cm or more. Tumors with a diameter of 5cm to 7cm or more should choose the latest third generation Super Needle warp. The newest third generation Super Multipole Needle developed by American RITA Company has an ablation diameter of more than 7cm at one time and uses a special syringe pump, which makes heat conduction faster and more uniform, treatment time significantly shortened, more accurate effect of treating large tumors, and more relaxed for patients. After the electrode needle is inserted into the tumor center, the electrode is unfolded and radiofrequency ablation is started. Under the action of 290kHz alternating current, the ions in the tissues rub against each other to generate heat, which then causes degeneration and necrosis of the tissues and inactivates the tumor cells in situ, and the inactivated cancer tissues are absorbed by the body to produce immune response. Radiofrequency ablation for local treatment of tumor is accepted because of its fast heating of tissues, heating up to 60-95℃, irreversible necrosis of tissues, complete hemostatic effect, easy to grasp heating range and easy to use. Radiofrequency ablation has achieved definite efficacy in the treatment of tumors. It has direct destructive effect on tumor tissues and can destroy and cut tumors. The highest temperature of local tumor treatment by radiofrequency ablation can be over 95℃, and the surrounding area can also be up to 60℃, which can not only treat huge tumors quickly but also tumors less than 3cm in diameter. However, it has little effect on the surrounding tissues. In addition, local heat therapy can enhance the immunity of the body and play an important role in curbing the regression of primary and metastatic tumors in other parts of the body. Radiofrequency ablation treatment can cause tumor cell denaturation and necrosis to significantly reduce tumor load, change certain inhibitory factors in the local environment of the body, and enable the immune function of t cells and NK cells to be restored and enhanced.