Mechanical Engineering Department, McGill University, Montreal, Canada.
Ultrasound Med Biol. 2011 Feb;37(2):301-11. doi: 10.1016/j.ultrasmedbio.2010.11.006.
Contrast agent microshells (CAMSs) are under intensive investigation for their wide applications in biomedical imaging and drug delivery. In drug delivery applications, CAMSs are guided to the targeted site before fragmentation by high-intensity ultrasound waves leading to the drug release. Prediction of the acoustic radiation force used to nondestructively guide a CAMS to the suspected site is becoming increasingly important and gaining attention particularly because it increases the system efficiency. The goal of this work is to present a theoretical model for the time-averaged (static) acoustic radiation force experienced by a CAMS near a blood vessel wall. An exact solution for the scattering of normal incident plane acoustic waves on an air-filled elastic spherical shell immersed in a nonviscous fluid near a porous and nonrigid boundary is employed to evaluate the radiation force function (which is the radiation force per unit energy density per unit cross-sectional surface). A particular example is chosen to illustrate the behavior of the time-averaged (static) radiation force on an elastic polyethylene spherical shell near a porous wall, with particular emphasis on the relative thickness of the shell and the distance from its center to the wall. This proposed model allows obtaining a priori information on the static radiation force that may be used to advantage in related as drug delivery and contrast agent imaging. This study should assist in the development of improved models for the evaluation of the time-averaged acoustic radiation force on a cluster of CAMSs in viscous and heat-conducting fluids.
对比剂微球（CAMS）因其在生物医学成像和药物输送中的广泛应用而受到广泛关注。在药物输送应用中，CAMS 在通过高强度超声波碎裂之前被引导到靶向部位，从而实现药物释放。预测用于将 CAMS 无损引导到可疑部位的声辐射力变得越来越重要，并且越来越受到关注，特别是因为它提高了系统效率。这项工作的目的是提出一种用于血管壁附近 CAMS 所经历的时间平均（静态）声辐射力的理论模型。采用了一种精确的方法来求解在多孔和非刚性边界附近充满非粘性流体的弹性球形壳对法向入射平面声波散射的问题，以评估辐射力函数（即单位能量密度每单位横截面的辐射力）。选择了一个特定的例子来说明弹性聚乙烯球形壳在多孔壁附近的时间平均（静态）辐射力的行为，特别强调了壳的相对厚度和其中心到壁的距离。该模型可以提供有关静态辐射力的先验信息，这在药物输送和对比剂成像等相关领域可能会带来优势。这项研究应有助于开发改进的模型，以评估粘性和导热流体中 CAMS 群的时间平均声辐射力。
