High Intensity Focused Ultrasound (HIFU) for Biomedical and Dentistry Applications

Abstract

We study the physical phenomena and the application of HIFU (High Intensity Focused Ultrasound) using simulation and experiment. The experiment was done with a bowl-shaped focused ultrasound system. High speed videos of the generation of cavitation bubbles at the focal point of the HIFU are captured. We observed interesting bubble cloud structures, and stationary bubble oscillations. The system is then applied for dentistry applications. Firstly we use the HIFU to drive antibacterial nanoparticles into dentinal tubules for disinfection in root canal treatment. Initial results show delivery of these nanoparticle deep into the dentinal channels which are a few microns in size. Next we cultivate E. Faecalis biofilm, a common bacteria colony found in the mouth and teeth, on petri dish and in human tooth. Then we subject them for removal under strong HIFU for a period of time. We obtain positive results in the biofilm removal with the increasing HIFU sonification time. Separately, we simulate the interaction of a bubble with an ultrasound field near bio-materials such as fat, muscle and bone. The simulation shows extreme growth and collapse of the bubble under certain conditions. It is found that the formation and direction of the water jet during bubble collapse is highly dependent on the properties of the biomaterials nearby. These studies provide a foundation for better understanding of HIFU and its uses in medical treatment.