Goldstein Albert
Department of Radiology, Wayne State University, Detroit Receiving Hospital, Detroit, MI, USA.
Ultrasound Med Biol. 2006 Oct;32(10):1441-58. doi: 10.1016/j.ultrasmedbio.2006.06.013.
This review was written to aid ultrasonic investigators using spherically focused transducers. It introduces a new direct method for computing steady state focused beam patterns on personal computers in nonattenuating and attenuating fluids and tissues. The method results in single integral expressions for uniform transducer excitation that can easily be altered for nonuniform surface excitation (apodization) or focused ring transducers. Procedures for verifying the accuracy of the derived equations are demonstrated. It is shown that beam diffraction errors are larger the higher the fluid or tissue attenuation. An experimental procedure is presented for measuring the effective focal length and effective aperture size of a spherically focused transducer with a single experimental measurement in a fluid with known acoustic velocity. Procedures are suggested for reducing the errors caused by beam diffraction in fluid attenuation measurements, avoiding them entirely or estimating their magnitude when they cannot be avoided.
撰写本综述旨在帮助使用球面聚焦换能器的超声研究人员。它介绍了一种在非衰减和衰减流体及组织中，在个人计算机上计算稳态聚焦波束图案的新直接方法。该方法给出了用于均匀换能器激励的单积分表达式，可轻松针对非均匀表面激励（变迹）或聚焦环形换能器进行修改。展示了验证所推导方程准确性的步骤。结果表明，流体或组织的衰减越高，波束衍射误差就越大。提出了一种实验程序，用于在声速已知的流体中通过单次实验测量来测量球面聚焦换能器的有效焦距和有效孔径尺寸。建议了一些程序，以减少流体衰减测量中由波束衍射引起的误差，在无法避免时完全避免这些误差或估计其大小。
