Principle of tumor radiofrequency ablation therapy: Tumor radiofrequency ablation therapy (Radiofrequency Ablation, RFA) refers to the placement of unipolar or multipolar electrodes into the tumor tissue, through the electrode emits frequent changes of high-frequency alternating currents, so that conductive ions or polarized molecules within the tissue cells rapidly change direction and generate heat energy by mutual oscillation and friction, resulting in a local temperature of the tissue of more than 60 ℃. The tumor cells rapidly undergo protein denaturation and coagulation and necrosis, so as to achieve the purpose of tumor treatment. With the progress of applied physics and the innovation of cold cycle technology, it can overcome the defects of various technologies of microwave ablation and become a new generation of ablation technology with easy manipulation of thermal field effect, larger ablation range and more effective treatment. In recent years, the complete ablation effect and safety in radiofrequency treatment of liver tumors have been significantly improved, and the progress has been more rapid, paving a promising road for minimally invasive treatment of liver cancer. Advantages of radiofrequency ablation for liver cancer: minimally invasive advantages such as less pain, light trauma, quick recovery, fewer complications and shorter hospitalization time. For tumors adjacent to large blood vessels of liver, bile ducts and other deep and important structural parts, which are difficult or impossible to be removed by surgery, radiofrequency ablation technology shows its superiority. Scope of application of radiofrequency ablation therapy for tumors: 1. Patients have the desire to receive minimally invasive treatment with radiofrequency ablation; 2. Tumors with a diameter of less than 5 cm, single or multiple less than 3 foci, and no distant metastasis; 3. Liver reserve function is poor, which makes it difficult or impossible to be resected by surgical resection; 4. Patients who are unwilling or unable to accept liver transplantation; 5. Patients with unsatisfactory therapeutic effect after TACE; 6. Tumors located on the surface of liver or near the surface, especially adjacent to the diaphragm, or near the surface of liver, or near the surface of liver. The tumor is located on or near the surface of the liver, especially adjacent to the diaphragm, stomach, colon and other important organs; 7. The tumor is located in the 1st and 2nd hepatic hilar, the caudate lobe, the right anterior and right posterior lobe of the liver in the upper part (liver segment I/VII/VIII), the sagittal part of the portal vein, adjacent to the inferior vena cava and other important bile ducts, blood vessels and other special parts of the liver.