NUMERICAL SIMULATION OF SHOCKWAVE LITHOTRIPSY

过去十年进行的SWL研究表明，与聚焦冲击波的直接相互作用以及空化气泡的膨胀和破裂引起的二次应力可能会产生足以引起碎裂和细胞水平组织损伤的应力。 拟议的研究将为 SWL 期间发生的体外和体内流体和固体动力学过程提供详细的建模和模拟。具体目标是： 1. 对流体状态下聚焦冲击波和空化气泡云产生的作用于结石和软组织的应力进行建模和计算机模拟。 2. 计算机模拟现实石材模型中的动态断裂和破碎过程，包括跟踪每个断裂的起源和扩展。 3.对解剖学上正确的有限元模型肾脏和其中的单个结构中的软组织损伤进行定量评估。 建模工作受到实验证据的范围和性质的密切指导，这些实验证据可通过与计划项目组的密切合作获得，可用于校准和验证模型。这些数据包括通过猪肾脏计算机分割的数字图像对肾脏几何形状和损伤进行定量评估、体外和体内详细的压力水听器测量、气泡云和冲击波的超高速摄影、结石碎裂数据、应变率依赖性材料行为的机械测试以及结石结构和断裂的超声断层扫描。通过致力于建立一个能够对结石粉碎和组织损伤的解剖学和机械正确模型进行全面分析的集成模拟设施，将对临床应用的影响最大化。该模拟设施将具有前所未有的预测能力，最终可能展示如何以更少的冲击和更少的肾损伤来粉碎结石。

Research in SWL conducted over the past ten years has shown that stresses sufficient to induce both fragmentation and cellular-level tissue damage can result from direct interaction with the focusing shockwave as well as secondary stresses induced by the expansion and collapse of cavitation bubbles. The proposed research will provide a detailed modeling and simulation of the fluid and solid-dynamical processes that occur both in vitro and in vivo during SWL. The specific aims are: 1. Modeling and computer simulation of the stresses acting on stones and soft tissue that results from the focusing shockwaves and clouds of cavitations bubbles in the fluid state. 2. Computer simulation of the dynamic fracture and fragmentation process in realistic stone models, including tracking the origin and propagation of each fracture. 3. Quantitative assessment of soft tissue damage in anatomically correct finite element models kidneys and individual structures therein. The modeling effort is closely guided by the extent and nature of the experimental evidence, available from close collaboration with the Program Project Group, that can be used to calibrate and validate the models. These data include quantitative assessment of kidney geometry and damage through digital images from a computer segmentation of pig kidneys, detailed pressure hydrophone measurements in vitro and in vivo, ultra-high-speed photography of bubble clouds and shockwaves, data on stone fragmentation, mechanical testing of strain-rate dependent material behavior, and ultrasound tomography of the structure and fracture of stones. Impact on clinical application will be maximized by working toward an integrated simulation facility capable of full-scale analysis of anatomically and mechanically correct models of stone comminution and tissue injury. The simulation facility will allow unprecedented predictive power that may ultimately show how to pulverize stones with fewer shocks and less renal injury.