Biological Effect And Stability Study Of Self-focusing Ultrasound System

For 50 years, focused ultrasound(FU) has been a subject of interest for medical research. Focused ultrasound causes selective tissue necrosis through heating or cavitation effect. In order to further analyze the practical application of this technology, self-focusing ultrasound system(Model ZH-2000) developed in this laboratory is used to study typical biological effect induced by this system as well as the stability of this system. Typical biological effect includes in vitro swine subcutaneous adipose tissue biological effect and in vitro bovine liver biological effect.Over the past few years, FU has been investigated in body contouring through destruction of fat cells. This technology has attracted the interest of researchers around the world but lacks enough basic experiments evaluating biological effects on different layers of adipose tissue using different ultrasonic frequency. Result shows that 3MHz FU can pass through skin of thickness 5mm and cause coagulative necrosis of the different layers of the fat. Disrupted area of the fat cells increases with increase in irradiation time and decreases with increase in ultrasonic power.Further, evaluations of fast scanning biological experiments are performed. Different modes of ablation such as dot mode, linear mode and circular mode are used in the experiment and hence feasibility of high and low frequency ultrasound in human body is studied. Result shows that the scanning speed of 8-10 MHz focused ultrasound can be up to 4mm/s. With this scanning speed, high frequency FU is applicable in shallow tissues whereas low frequency FU is applicable in deep tissues. In presence of adipose tissue on the path of scanning, lipolysis experiment provides us further basic information.Evaluation of the stability of the self-focusing ultrasound system is also performed in this article. Study on different factors that might influence the stability of the system is performed. Results show that working status of digital power generator and self-focusing transducer play important role in the stability of the whole system. On the other hand, result shows no significant difference in area of biological focal region(BFR) induced by these elements under normal working condition.