Department of Mechanical Engineering, College of Industrial Technology, Nihon University, Narashino, Chiba 275-8575 Japan.
J Acoust Soc Am. 2013 Aug;134(2):1576-85. doi: 10.1121/1.4812880.
The enhancement of heating due to inertial cavitation has been focused to reduce the long treatment time of conventional high-intensity focused ultrasound (HIFU) therapy. The influences of the physical properties of surrounding tissues, initial void fraction, and spatial distribution of bubbles on microbubble-enhanced HIFU are examined. A bubble dynamics equation based on the Keller-Miksis equation is employed in consideration of the elasticity of surrounding tissue. The mixture phase and bubbles are coupled by the Euler-Lagrange method to take into account the interaction between ultrasound and bubbles. As a result, the temperature around the target increases with the initial void fraction. But at the high void fraction of 10(-5), ultrasound is too attenuated to heat the target, and the heating region moves to the transducer side. On the other hand, both the viscosity and shear elasticity of the surrounding media reduce the attenuation of ultrasound propagation through the bubbly mixture. Numerical results show that localized heating is induced with increasing viscosity or shear elasticity, though it depends on the pressure amplitudes. In addition, it was numerically confirmed that the localization of the microbubble distribution is important to obtain efficient localized heating.
由于惯性空化而增强的加热已被集中用于减少传统高强度聚焦超声（HIFU）治疗的长治疗时间。研究了周围组织的物理性质、初始空泡分数和气泡的空间分布对微泡增强 HIFU 的影响。基于 Keller-Miksis 方程的气泡动力学方程考虑了周围组织的弹性。通过欧拉-拉格朗日方法将混合物相和气泡耦合，以考虑超声与气泡之间的相互作用。结果，目标周围的温度随初始空泡分数的增加而升高。但是，在 10(-5) 的高空泡分数下，超声衰减过大，无法加热目标，加热区域移向换能器侧。另一方面，周围介质的粘度和剪切弹性都会降低通过泡沫混合物的超声传播衰减。数值结果表明，随着粘度或剪切弹性的增加，会产生局部加热，尽管这取决于压力幅度。此外，数值上证实了微泡分布的定位对于获得有效的局部加热很重要。
