Treatment of liver tumor was firstly applied in 1995 by ROSSI in Italy, which is one of the latest liver tumor oriented treatment methods today. By generating heat energy to destroy tumor cells, when tumor cells are heated over 45~50℃, intracellular proteins are denatured and cell membrane double lipid membrane is dissolved leading to cell membrane destruction, thus cell structure is changed. Radiofrequency ablation technology can destroy tumor cells by making the intracellular temperature exceed 60℃. The basic principle and operation of radiofrequency ablation The earliest report on the treatment of tumor by heat energy is the record of early Egyptians and Greeks who used thermal branding to treat body surface swelling. In general, the time required for heat to cause cellular damage varies from 3 to 50 hours depending on different tissue types and different specific conditions, and the time required to cause cellular damage decreases exponentially when the temperature rises greater than 42°C. For example, when the temperature reaches 46°C it takes 8 minutes to kill tumor cells, while when the temperature reaches 51°C it takes only 2 minutes to kill tumor cells. When the temperature exceeds 60°C, intracellular proteins denature and the double lipid membrane melts, and cell death is inevitable. The nascent tumor vessels have certain physiological regulation defects, which are more tolerant to low temperature than normal cells, and less tolerant to high temperature than normal tissues. In recent years, radiofrequency generating heat energy to cause tissue necrosis has become more and more a hot spot for research and clinical application. In the application of radiofrequency ablation treatment, the high frequency alternating current from the tip of the electrode is shot into the tissue around the electrode, and the ions in the tissue change with the direction of the current, thus generating heat by friction, and when the temperature of the tissue exceeds 60℃, the cells die and regional tissue necrosis occurs around the electrode. The standard radiofrequency treatment technology can make the local tissue temperature exceed 100℃, causing coagulative necrosis of tumor tissue and the surrounding liver parenchyma, and at the same time, the vascular tissue around the tumor coagulates to form a reaction zone, so that it cannot intermittently supply blood to the tumor and prevent tumor metastasis. The microvasculature of the tissue is completely destroyed, and the hepatic artery, portal vein and hepatic vein less than 3mm in diameter are embolized. The large blood vessels, however, can quickly take away the heat generated by the radiofrequency because of the faster blood flow, which will not cause the blood vessels to increase in temperature and damage them. The heat energy will produce a well-defined spherical necrosis of the tissues around the electrode, causing the destruction and death of the tumor tissues covered by this area. The charring of the tissue around the electrode due to overheating increases the impedance of the tissue and decreases the release of RF energy. Eventually the heat energy causes the size of the necrotic zone to be proportional to the square of the RF current (called RF energy density), and the energy produced by the monopolar RF needle decreases proportionally to the square of the distance from the electrode. Therefore, the diameter of coagulative necrotic zone caused by traditional unipolar RF needle can only reach 1.6cm at maximum. The newly developed multipolar RF needle has multiple arc-shaped electrodes, and when the insulated sheath of the electrode enters the tumor, the electrode shrinks inside the sheath, and under the guidance of real-time ultrasound, the electrode pops open in a radial daisy shape inside the tumor, forming a 2.0~5.0cm diameter electrode cluster, thus increasing the range of RF ablation destruction. The range of tumor destruction can be increased, and the coagulative necrosis of tissues can reach about 6cm at one time. RF electrodes can be used percutaneously, laparoscopically and intraoperatively to treat liver malignant tumors and metastatic tumors that cannot be removed surgically. Under the guidance of extracorporeal ultrasound and intraoperative ultrasound, the needle sheath enters the tumor and then each electrode is popped off and pierced into the tissue, and the electrode needle is connected to the RF generating device, and another electrode is connected to each of the lower extremities as the ground line to calculate the magnitude of RF energy for RF treatment. When the tumor diameter is less than 2.5cm, the 3.5cm diameter RF needle can be inserted directly into the center of the tumor to destroy the tumor, for larger tumors, multiple punctures are possible to achieve complete destruction of the tumor by popping open at different locations inside the tumor. The general practice is that the radiofrequency needle is first placed at the junction of liver and tumor opposite to the puncture point and the scope of popping and destruction should not be limited to the tumor tissue, then the needle is withdrawn and the needle sheath is retired at an interval of 2.0~2.5cm and popped and destroyed again. Similar to surgical resection, the scope of thermal destruction should not be limited to the tumor tissue, but should also include the surrounding 1 cm of normal liver tissue. Postoperative CT examination is routinely performed, and a cystic mass can be found, which gradually shrinks with the progress of time.