The present study aims to investigate temperature distribution caused by bubble oscillations in a soft tissue during focused ultrasound therapy by introducing a coupled temperature-cavitation model. The proposed model is capable of describing bubble dynamics, viscoelastic properties of surrounding tissue-like medium, temperature distribution inside and outside the bubble, vapor diffusion within the bubble and vapor flux through the bubble wall to the exterior. The continuous temperature distribution inside and outside the oscillating bubble in soft tissue subject to ultrasound wave with high acoustic pressure is presented. The temperature close to the bubble wall can reach the value of about ${10}^3$ K. The elasticity of soft tissue reduces temperature values. The relaxation time effect strongly depends on the period of the ultrasound wave. If the vapor mass flux effect is taken into account in the simulations, the rectified growth effect can be observed, which can lead to the decrease of the temperature values. Due to the growth of the bubble, the effects of elasticity and relaxation time on the temperature become less prominent during several bubble oscillation cycles. The impact of cavitation heat source terms on the exterior temperature was examined and led us to draw conclusion that, even though these heat sources can increase the outside temperature values, they can not be treated as main mechanisms for the temperature elevation during a few microseconds. The performed comparison with uncoupled conventional model for the outside temperature calculation revealed that coupling with inside temperature model delivers incomparably higher values to the bubble’s exterior and, therefore, it is essential for the accurate description of the treatment process.

本研究旨在通过引入耦合的空化模型来研究聚焦超声治疗过程中由软组织中的气泡振荡引起的温度分布。所提出的模型能够描述气泡动力学，周围组织样介质的粘弹性，气泡内部和外部的温度分布，气泡内部的蒸汽扩散以及通过气泡壁到外部的蒸汽通量。给出了在具有高声压的超声波作用下的软组织中振荡气泡内部和外部的连续温度分布。靠近气泡壁的温度可以达到约${10}^3$K.软组织的弹性会降低温度值。弛豫时间效应在很大程度上取决于超声波的周期。如果在仿真中考虑了蒸气质量通量效应，则可以观察到整流的生长效应，这可能导致温度值降低。由于气泡的增长，在几个气泡振荡周期中，弹性和松弛时间对温度的影响变得不那么明显。检验了空化热源条件对外部温度的影响，使我们得出结论，即使这些热源可以增加外部温度值，也不能将其视为几微秒内温度升高的主要机制。