1 Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana.
J Endourol. 2014 Apr;28(4):446-52. doi: 10.1089/end.2013.0662. Epub 2014 Jan 8.
Determine the influence of passage through the body wall on the properties of lithotripter shock waves (SWs) and the characteristics of the acoustic field of an electromagnetic lithotripter.
Full-thickness ex vivo segments of pig abdominal wall were secured against the acoustic window of a test tank coupled to the lithotripter. A fiber-optic probe hydrophone was used to measure SW pressures, determine shock rise time, and map the acoustic field in the focal plane.
Peak positive pressure on axis was attenuated roughly proportional to tissue thickness-approximately 6% per cm. Irregularities in the tissue path affected the symmetry of SW focusing, shifting the maximum peak positive pressure laterally by as much as ∼2 mm. Within the time resolution of the hydrophone (7-15 ns), shock rise time was unchanged, measuring ∼17-21 ns with and without tissue present. Mapping of the field showed no effect of the body wall on focal width, regardless of thickness of the body wall.
Passage through the body wall has minimal effect on the characteristics of lithotripter SWs. Other than reducing pulse amplitude and having the potential to affect the symmetry of the focused wave, the body wall has little influence on the acoustic field. These findings help to validate laboratory assessment of lithotripter acoustic field and suggest that the properties of SWs in the body are much the same as have been measured in vitro.
确定穿过体壁对碎石机冲击波（SW）特性和电磁碎石机声场特性的影响。
将猪腹壁的全厚离体段固定在与碎石机耦合的测试槽的声窗上。光纤探头水听器用于测量 SW 压力、确定冲击波上升时间，并在焦平面上绘制声场图。
轴上的峰值正压衰减大致与组织厚度成正比-大约每厘米 6%。组织路径的不规则性影响了 SW 聚焦的对称性，使最大峰值正压横向移动多达约 2mm。在水听器的时间分辨率（7-15ns）内，冲击波上升时间不变，有和没有组织时分别测量为 17-21ns。声场的测绘显示体壁对焦点宽度没有影响，无论体壁的厚度如何。
穿过体壁对碎石机 SW 特性的影响很小。除了降低脉冲幅度和有可能影响聚焦波的对称性外，体壁对声场的影响很小。这些发现有助于验证碎石机声场的实验室评估，并表明体内 SW 的特性与体外测量的特性非常相似。
