Acoustic characteristics of shell encapsulated bubbles and gas bubbles

In clinical therapies, micro-bubbles can enhance thrombus formation rate in micro-vessel in order to cure tumour using low frequency ultrasound. However it is difficult to acquire their backscatter characters in experiments. By building the models of gas bubbles and shell-encapsulated bubbles, the motion procedures are simulated and derived. This paper analyzes the backscatter characters of the two kinds of bubbles by changing the frequency of the driving acoustic field and the initial equilibrium radius. It is concluded that shell encapsulated bubbles surpass gas bubbles in the aspects of backscatter when the initial equilibrium radius is greater than 2.2μm, and their maximal backscatter pressure and backscatter cross section decrease as the frequency of the driving acoustic field increases. The advantages of shell encapsulated bubbles make them more efficient in therapies and imaging using ultrasound. It provides a guide in investigations and applications of bubbles such as ultrasonic contrast agents.