Acoustic characterization of high intensity focused ultrasound fields: A combined measurement and modeling approach
Acoustic characterization of high intensity focused ultrasound fields: A combined measurement and modeling approach
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DOI：
10.1121/1.2967836
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发表时间：
2008-10-01
影响因子：
2.4
通讯作者：
Sapozhnikov, Oleg A.
中科院分区：
文献类型：
--
作者：
Canney, Michael S.;Bailey, Michael R.;Sapozhnikov, Oleg A.
高强度聚焦超声(HIFU)场的声学特性对于准确预测超声在组织中的生物效应和制定临床HIFU设备的监管标准都是重要的。本文提出了一种确定焦点处及周围的HIFU场参数的方法。在2 MHz口径、焦距4.4 cm的换能器上，在水和仿组织凝胶体模中测量和模拟了非线性压力波形。测量采用光纤探头水听器，最高强度可达24000W/cm(2)。Khokhlov-Zbolotskaya-Kuznetsov型数值模式的输入是基于实验的低幅度束流曲线图确定的。数值和实验都得到了峰值正压高达80 Mpa，峰值负压高达15 Mpa的强不对称波形。数值模拟结果与实验测量结果吻合较好，但当激波强度大于6000W/cm(2)时，测得的波形峰值正压值较低。这一数字偏低的主要原因是水听器带宽有限，仅为100兆赫。结果表明，为了能够准确地表征HIFU场，测量和建模的结合是必要的。(C)2008年美国声学学会。
Acoustic characterization of high intensity focused ultrasound (HIFU) fields is important both for the accurate prediction of ultrasound induced bioeffects in tissues and for the development of regulatory standards for clinical HIFU devices. In this paper, a method to determine HIFU field parameters at and around the focus is proposed. Nonlinear pressure waveforms were measured and modeled in water and in a tissue-mimicking gel phantom for a 2 MHz transducer with an aperture and focal length of 4.4 cm. Measurements were performed with a fiber optic probe hydrophone at intensity levels up to 24 000 W/cm(2). The inputs to a Khokhlov-Zabolotskaya-Kuznetsov-type numerical model were determined based on experimental low amplitude beam plots. Strongly asymmetric waveforms with peak positive pressures up to 80 MPa and peak negative pressures up to 15 MPa were obtained both numerically and experimentally. Numerical simulations and experimental measurements agreed well; however, when steep shocks were present in the waveform at focal intensity levels higher than 6000 W/cm(2), lower values of the peak positive pressure were observed in the measured waveforms. This underrepresentation was attributed mainly to the limited hydrophone bandwidth of 100 MHz. It is shown that a combination of measurements and modeling is necessary to enable accurate characterization of HIFU fields. (c) 2008 Acoustical Society of America.