Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA.
J Acoust Soc Am. 2010 Apr;127(4):2635-45. doi: 10.1121/1.3308409.
Using a reflector insert, the original HM-3 lithotripter field at 20 kV was altered significantly with the peak positive pressure (p(+)) in the focal plane increased from 49 to 87 MPa while the -6 dB focal width decreased concomitantly from 11 to 4 mm. Using the original reflector, p(+) of 33 MPa with a -6 dB focal width of 18 mm were measured in a pre-focal plane 15-mm proximal to the lithotripter focus. However, the acoustic pulse energy delivered to a 28-mm diameter area around the lithotripter axis was comparable ( approximately 120 mJ). For all three exposure conditions, similar stone comminution ( approximately 70%) was produced in a mesh holder of 15 mm after 250 shocks. In contrast, stone comminution produced by the modified reflector either in a 15-mm finger cot (45%) or in a 30-mm membrane holder (14%) was significantly reduced from the corresponding values (56% and 26%) produced by the original reflector (no statistically significant differences were observed between the focal and pre-focal planes). These observations suggest that a low-pressure/broad focal width lithotripter field will produce better stone comminution than its counterpart with high-pressure/narrow focal width under clinically relevant in vitro comminution conditions.
使用反射镜插入物，将原始 HM-3 碎石器场在 20 kV 下进行了重大改变，焦平面上的峰正压（p(+)）从 49 MPa 增加到 87 MPa，而 -6 dB 焦宽相应地从 11 mm 减小到 4 mm。在碎石器焦点前 15-mm 的预焦平面处，使用原始反射镜测量到的 p(+)为 33 MPa，-6 dB 焦宽为 18 mm。然而，在碎石器轴周围 28-mm 直径区域内输送的声脉冲能量相当（约 120 mJ）。在所有三种暴露条件下，在 250 次冲击后，在 15-mm 的网格支架中产生了类似的结石粉碎（约 70%）。相比之下，在 15-mm 指套（45%）或 30-mm 膜架（14%）中，使用改良反射镜产生的结石粉碎明显低于原始反射镜（56%和 26%）对应的粉碎率（在焦点和预焦点平面之间未观察到统计学上的显著差异）。这些观察结果表明，在临床相关的体外粉碎条件下，与高压/窄焦宽碎石器场相比，低压/宽焦宽碎石器场将产生更好的结石粉碎效果。
