Burst wave lithotripsy (BWL) is a technology for comminuting urinary stones. A BWL transducer's requirements of high-pressure output, limited acoustic window, specific focal depth, and frequency to produce fragments of passable size constrain focal beamwidth. However, BWL is most effective with a beam wider than the stone. To produce a broad-beam, an iterative angular spectrum approach was used to calculate a phase screen that was realized with a rapid prototyped lens. The technique did not accurately replicate a target beam profile when an axisymmetric profile was chosen. Adding asymmetric weighting functions to the target profile achieved appropriate beamwidth. Lenses were designed to create a spherically focused narrow-beam (6 mm) and a broad-beam (11 mm) with a 350-kHz transducer and 84-mm focal depth. Both lenses were used to fragment artificial stones (11 mm long) in a water bath, and fragmentation rates were compared. The linearly simulated and measured broad beamwidths that were 12 mm and 11 mm, respectively, with a 2-mm-wide null at center. The broad-beam and the narrow-beam lenses fragmented 44 ± 9% and 16 ± 4% (p = 0.007, N = 3) of a stone by weight, respectively, in the same duration at the same peak negative pressure. The method broadened the focus and improved the BWL rate of fragmentation of large stones.

中文翻译：

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用于通过突发波碎石术碎裂大肾结石的宽束换能器的设计、制造和表征。

突发波碎石术（BWL）是一种粉碎尿路结石的技术。BWL 换能器对高压输出、有限声窗、特定焦点深度和产生合格尺寸碎片的频率的要求限制了焦点波束宽度。然而，当光束比石头更宽时，BWL 最为有效。为了产生宽光束，使用迭代角谱方法来计算通过快速原型透镜实现的相位屏幕。当选择轴对称轮廓时，该技术无法准确地复制目标光束轮廓。向目标轮廓添加不对称加权函数可实现适当的波束宽度。透镜设计用于创建球面聚焦窄光束 (6 mm) 和宽光束 (11 mm)，并配有 350 kHz 换能器和 84 mm 焦深。两种镜片均用于在水浴中破碎人造石（11 毫米长），并比较破碎率。线性模拟和测量的宽波束宽度分别为 12 毫米和 11 毫米，中心零点宽度为 2 毫米。在相同的峰值负压下，在相同的持续时间内，宽光束和窄光束透镜分别破碎了按重量计 44 ± 9% 和 16 ± 4%（p = 0.007，N = 3）的石头。该方法拓宽了聚焦范围，提高了大结石的BWL破碎率。