First, the physical basis of the HEFL knife: ultrasound is a mechanical wave, with good directionality and focus. When ultrasonic waves propagate in biological tissues, biological tissues are first subjected to mechanical action, and part of the mechanical energy is converted into heat energy. When the sound intensity is strong enough, it may also produce cavitation effect. Therefore, the biological effect of ultrasound originates from its mechanical effect, warm-heat effect and cavitation effect. Conventional ultrasound treatment mainly uses the thermal effect of ultrasound, while the biological effect produced by the HEF is the combined effect of mechanical, thermal and cavitation effects under high intensity conditions. Experiments using ultrasound to terminate early pregnancy have demonstrated that ultrasound can be further used for clinical treatment. Highly focused ultrasound beams can damage or destroy tissues within a specific range under effective control, and can replace the scalpel with the advantages of rapid operation and minimal bleeding. Ultrasound focused beams have achieved good results in surgical treatment studies of brain, liver, kidney, spinal cord, teeth, eyes and ears, such as Meniere’s disease. Research has also confirmed that ultrasound is a non-invasive heating method that does not cause rupture of blood vessels and lymph vessels around the tumor, leading to metastasis and spread of tumor cells, thus making ultrasound available for heating treatment of tumors, and it has become the most successful direction of ultrasound therapy. Ultrasound is superior to electromagnetic radiation (X-rays, gamma rays) in that it is non-radioactive, highly focused, and can control the local temperature of deep tumors without damaging the surrounding normal tissues, and the treatment site and treatment intensity can be remotely controlled. Ultrasound treatment of tumors also depends on the biological characteristics of the tumor tissue itself. Due to the defects in anatomy and histology, tumor tissues are characterized by insufficient blood supply, lack of oxygen, warmth and heat resistance, which provides the theoretical basis for ultrasound warming to treat cancer. Tumor tissues cannot dissipate heat after absorbing thermal energy, and the internal temperature can rise beyond healthy tissues by 5~9℃, sometimes even as high as 10~11℃, and maintain for a long time. The selective effect of ultrasound on cancerous tumor tissues can make it achieve the purpose of killing cancerous tissues without damaging normal tissues. Ultrasound can also change the acidity of the environment around the tumor cells, lower the PH value, strengthen the lysosomal enzyme activity, and accelerate the destruction of malignant tumor cells by lysosomes. Ultrasound is more destructive to tumor cells with vigorous DNA synthesis, because the DNA synthesis period is sensitive to heat. Differences in sensitivity to ultrasound exist not only between cancer cells and normal tissues, but also between embryonic and maternal tissues, bone or stones and soft tissues. Different biological tissues produce different biological effects, which provides prerequisites for the treatment of solid tumors such as liver cancer, breast cancer, and malignant bone tumors with the Helio knife. Second, the therapeutic effect of Helioplasty: The scope of deep tissue damage by focused ultrasound is the key to the unification of therapeutic effect and safety. The size of the focal field, the ultrasound dose, the thermal sensitivity of the tissue, the thermal conductivity of the tissue and the blood flow rate together determine the damage range of the target tissue. In short, the size of the tissue coagulation necrosis range is a very important parameter. Within the biological focal range, coagulative necrosis occurs in liver tissue, while adjacent tissue and ultrasound-transmitting tissue are not damaged. The Hefner knife can warm the tissue within the focal domain by more than 70°C in a short time (within seconds), which fully meets the internationally accepted standard. The main parameters that determine the biological focal area are sound intensity, frequency, irradiation time and frequency, interval time, irradiation mode, etc. The optimal dynamic mode of treatment is determined based on clinical experimental research findings. Not only does the knife have a direct effect on tumor tissue, but research shows that ultrasound therapy also has a sensitizing effect on chemotherapy, stimulating the body’s immune system and improving the body’s immune function. HIFU uses quantitative analysis of ultrasound images in treatment to monitor the morphological changes of damaged tissues after HIFU treatment. Echo enhancement is a criterion for effective treatment and is a characteristic sign of coagulative necrosis of tissues or lesions. The sonogram of effective treatment is characterized by a marked increase in the echogenicity of the cancer mass after treatment followed by a gradual decrease and finally a heterogeneous enhancement, with images of necrotic liquefied dark areas or foci of calcification, a gradual decrease in the size of the cancer mass and a marked decrease or disappearance of the blood supply. Within one to several months, the central area of the lesion is hypoechoic and the marginal area is echogenic, and the absence of blood supply is the most characteristic phenomenon. When HIFU treatment raises the tissue temperature in the target area above 65°C, the temperature nociceptive threshold of visceral and somatic nerves is exceeded, and coagulative necrosis occurs instantaneously in the lesioned tissue. In order to eliminate the pain caused by high temperature and coagulative necrosis, as well as to ensure the accuracy in treatment and to avoid off-target occurrence, general anesthesia is required for the patient during the procedure. This is a necessary adjunct to HIFU treatment, and is a conclusion clearly made by the NIDA Expert Symposium, the three International Symposiums on the Medical Applications of HIFU, and the Special Committee on Ultrasound Therapy. Research through HIFU treatment for primary liver cancer shows that after treatment, patients’ clinical symptoms are reduced, serum AFP level decreases, lesions shrink, tumor blood supply decreases or disappears, no local complications appear, heart and kidney functions are normal, but there is a transient increase in liver enzyme spectrum, and histopathological and other examinations reveal coagulative necrosis of tumor tissues. The efficacy of hepatocellular carcinoma treatment mainly depends on whether its treatment scope can completely cover the tumor or whether improper operation leads to off-target situation. On the one hand, patients with hepatocellular carcinoma are mostly in advanced stage when they are treated by Heliport, with multiple metastases in the liver, portal vein cancer thrombosis, cirrhosis, portal hypertension and ascites, which are patients that other departments dare not treat, making Heliport treatment more difficult. On the other hand, it also shows that Helio knife has certain advantages in treating such advanced patients. In addition to complete removal of tumor tissues, the biggest advantage is that the appearance of breast and limbs can be preserved intact. At present, Hedgehog knife has been used in 18 centers nationwide and hospitals in the UK and Japan, and has treated more than 4,000 patients with various types of solid tumors, including liver cancer, breast cancer, malignant bone tumors, soft tissue tumors, kidney cancer, pelvic tumors, retroperitoneal tumors, pancreatic cancer, metastatic tumors, palliative treatment of advanced malignant tumors, solid tumors that recur after surgery, partial tumors that cannot be removed by surgery, various body surface tumors, uterine fibroids, benign breast tumors, benign soft tissue tumors, other solid tumors, etc. With the continuous expansion of clinical application, the indications for Hepatome treatment will continue to increase. Features of HIFU: The advanced nature of HIFU technology theory must be reflected by excellent equipment design and manufacturing process. The device involves medical, biomedical engineering, ultrasonics, automation control, computers, precision machinery manufacturing and many other technologies, must achieve the following functional requirements: (1) non-invasive focus or convergence of the acoustic beam; (2) to make the ultrasound has the appropriate frequency and high intensity acoustic power, heating to be limited to the target tissue and prevent the surrounding normal tissue overheating; (3) scanning so that the energy distribution in the entire target tissue The scanning speed or focal energy should be high enough to ensure that the target tissue can quickly raise the temperature in the case of heat dissipation; (4) to heat different forms of target tissue with easily adaptable and adjustable scanning trajectories, adjust the treatment volume, and obtain the ideal temperature distribution; (5) due to the different thickness of the tissue covering the treatment field, high-precision compensation is required, and the normal tissue near the irradiated field that is particularly sensitive to temperature should be protected.