带球壳微泡和空化气泡的超声特性研究

Acoustic characteristics of shell encapsulated bubbles and gas bubbles

在临床应用中,微泡在低频超声作用下能比较成功地导致微血管的栓塞,从而切断对肿瘤的供血来达到杀灭肿瘤的目的,而通过实验的手段来获得其微泡的超声散射特性十分困难。根据经典的微泡模型,应用范德瓦耳斯绝热方程来进行修正,分别对带球壳微泡和空化气泡建立模型,模拟其运动过程,并对两种微泡的散射特性进行了分析与比较,研究了不同驱动声场的频率和微泡初始平衡半径对微泡运动的影响。结果表明,带球壳微泡在微泡初始平衡半径大于2.2μm时较空化气泡有较好的散射特性,其最大散射压力和散射截面随着频率的增大而减小,带球壳微泡在散射特性方面的优势使其能更有效地进行超声治疗和成像,为超声造影剂等微泡的研究和应用提供了理论指导。

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 encapsu- lated 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.