Focused ultrasound transducer spatial peak intensity estimation: a comparison of methods.
Focused ultrasound transducer spatial peak intensity estimation: a comparison of methods.
复制标题
DOI：
10.1088/1361-6560/aaaf01
复制
发表时间：
2018-03-07
影响因子：
3.5
通讯作者：
Ter Haar G
中科院分区：
文献类型：
--
作者：
Civale J;Rivens I;Shaw A;Ter Haar G
高强度聚焦超声（HIFU）换能器焦点处的空间峰值强度的表征是困难的，因为在所产生的高焦点压力下存在损坏水听器传感器的风险。提供了一个简单的公式，用于估计空间峰值强度的固体球碗换能器使用测量的声功率和焦点波束宽度。本文从理论上和实验上证明，该表达式仅对没有中心（成像）孔径的球碗换能器严格有效。换能器中心的孔导致峰值强度的高估。提出了从总声功率测量确定焦峰强度的改进策略。比较了四种方法：（i）固体球碗近似（后），（ii）从理论导出的数值方法，（iii）使用测量的旁瓣到焦点峰值压力的方法，以及（iv）用于实验地测量焦点功率分数（FPF）的方法。在三种驱动功率水平下估计了8个换能器的空间峰值强度：低（约1 W）、中等（约10 W）和高（20 - 70 W）。计算出的强度进行了比较，来自使用校准水听器的焦点峰值压力测量。发现FPF测量方法提供的焦峰强度估计值与水听器测量值最接近（在15%以内），其次是压力比方法（在20%以内）。发现数值方法始终高估局灶峰强度（平均+40%），但是，对于具有中心孔的探头，其比使用实心碗假设更准确（高估+70%）。总之，利用自动波束绘图系统和具有良好空间分辨率的水听器的能力极大地促进了FPF的表征，并因此提高了从声功率测量估计空间峰值强度的置信度。
Characterisation of the spatial peak intensity at the focus of high intensity focused ultrasound (HIFU) transducers is difficult because of the risk of damage to hydrophone sensors at the high focal pressures generated. provided a simple equation for estimating spatial-peak intensity for solid spherical bowl transducers using measured acoustic power and focal beamwidth. This paper demonstrates theoretically and experimentally that this expression is only strictly valid for spherical bowl transducers without a central (imaging) aperture. A hole in the centre of the transducer results in over-estimation of the peak intensity. Improved strategies for determining focal peak intensity from a measurement of total acoustic power are proposed. Four methods are compared: (i) a solid spherical bowl approximation (after), (ii) a numerical method derived from theory, (iii) a method using measured sidelobe to focal peak pressure, and (iv) a method for measuring the focal power fraction (FPF) experimentally. Spatial-peak intensities were estimated for 8 transducers at three drive powers levels: low (approximately 1W), moderate (~10W) and high (20 - 70W). The calculated intensities were compared with those derived from focal peak pressure measurements made using a calibrated hydrophone. The FPF measurement method was found to provide focal peak intensity estimates that agreed most closely (within 15%) with the hydrophone measurements, followed by the pressure ratio method (within 20%). The numerical method was found to consistently over-estimate focal peak intensity (+40% on average), however, for transducers with a central hole it was more accurate than using the solid bowl assumption (+70% overestimation). In conclusion, the ability to make use of an automated beam plotting system, and a hydrophone with good spatial resolution, greatly facilitates characterisation of the FPF, and consequently gives improved confidence in estimating spatial peak intensity from measurement of acoustic power.
登录
查看更多内容
DOI：
10.1016/j.jacr.2009.01.004
发表时间：
2009-07-01
期刊：
Journal of the American College of Radiology : JACR
影响因子：
--
作者：
Bradley, William G Jr
通讯作者：
Bradley, William G Jr
影响因子：
2.9
作者：
Civale, John;Clarke, Robert;Ter Haar, Gail
通讯作者：
Ter Haar, Gail
影响因子：
4.6
作者：
Farny, Caleb H.;Holt, R. Glynn;Roy, Ronald A.
通讯作者：
Roy, Ronald A.
影响因子：
8.8
作者：
通讯作者：
--
影响因子：
3.7
作者：
Feng, W;Wang, ZB;Su, HB
通讯作者：
Su, HB