Loske Achim M, Prieto Fernando E, Fernandez Francisco, van Cauwelaert Javier
Centro de Física Aplicada y Tecnología Avanzada, UNAM, Campus Juriquilla, Querétaro, Mexico.
Phys Med Biol. 2002 Nov 21;47(22):3945-57. doi: 10.1088/0031-9155/47/22/303.
Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 micros is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 micros using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator.
体外冲击波碎石术（ESWL）在治疗肾结石患者方面已经成功应用了二十多年。在患者体外产生数百次水下冲击波，并聚焦于肾结石。结石破碎主要是由于剥落、空化和层离。每次冲击波的拉伸阶段会在结石附近产生空化气泡。气泡膨胀、稳定，最终剧烈坍塌，产生破坏结石的二次冲击波和微射流。通过在第一次冲击波后几百微秒发送第二次冲击波，可以增强气泡坍塌。本文描述并测试了一种产生两个压电冲击波的新方法，其时间延迟可在50至950微秒之间调节。目的是在ESWL期间增强空化对肾结石的损伤，以减少治疗时间。将体外肾结石模型的破碎效率和压力测量结果与标准ESWL系统的结果进行了比较。结果表明，分别使用矩形和球形结石模型时，在约400微秒和250微秒的冲击波延迟下，破碎效率显著提高。这里介绍的系统可以以相对较低的成本安装在临床设备中，无需第二个冲击波发生器。
