修正高强度治疗超声水听器测量中的空间平均伪影：逆滤波方法。
Correction for Spatial Averaging Artifacts in Hydrophone Measurements of High-Intensity Therapeutic Ultrasound: An Inverse Filter Approach.
出版信息
IEEE Trans Ultrason Ferroelectr Freq Control. 2019 Sep;66(9):1453-1464. doi: 10.1109/TUFFC.2019.2924351. Epub 2019 Jun 24.
High-intensity therapeutic ultrasound (HITU) pressure is often measured using a hydrophone. HITU pressure waves typically contain multiple harmonics due to nonlinear propagation. As harmonic frequency increases, harmonic beamwidth decreases. For sufficiently high harmonic frequency, beamwidth may become comparable to the hydrophone effective sensitive element diameter, resulting in signal reduction due to spatial averaging. An analytic formula for a hydrophone spatial averaging filter for beams with Gaussian harmonic radial profiles was tested on HITU pressure signals generated by three transducers (1.45 MHz, F/1; 1.53 MHz, F/1.5; 3.91 MHz, F/1) with focal pressures up to 48 MPa. The HITU signals were measured using fiber-optic and needle hydrophones (nominal geometrical sensitive element diameters: 100 and [Formula: see text]). Harmonic radial profiles were measured with transverse scans in the focal plane using the fiber-optic hydrophone. Harmonic radial profiles were accurately approximated by Gaussian functions with root-mean-square (rms) differences between transverse scans and Gaussian fits less than 9% for frequencies up to approximately 50 MHz. The Gaussian harmonic beamwidth parameter σ varied with harmonic number n according to a power law, σ = σ/n where . RMS differences between experimental and theoretical spatial averaging filters were 11% ± 1% (1.45 MHz), 8% ± 1% (1.53 MHz), and 4% ± 1% (3.91 MHz). For the two more highly focused (F/1) transducers, the effect of spatial averaging was to underestimate peak compressional pressure (pcp), peak rarefactional pressure (prp), and pulse intensity integral (pii) by (mean ± standard deviation) (pcp: 4.9% ± 0.5%, prp: 0.4% ± 0.2%, pii: 2.9% ± 1%) and (pcp: 28.3% ± 9.6%, prp: 6% ± 2.4%, pii: 24.3% ± 6.7%) for the 100- and 400- [Formula: see text]-diameter hydrophones, respectively. These errors can be suppressed by the application of the inverse spatial averaging filter.
高强度治疗超声（HITU）压力通常使用水听器进行测量。由于非线性传播，HITU 压力波通常包含多个谐波。随着谐波频率的增加，谐波束宽减小。对于足够高的谐波频率，波束宽度可能与水听器有效敏感元件直径相当，导致由于空间平均而导致信号减少。对于具有高斯谐波径向分布的光束，水听器空间平均滤波器的解析公式在由三个换能器（1.45MHz，F/1；1.53MHz，F/1.5；3.91MHz，F/1）产生的 HITU 压力信号上进行了测试，焦点压力高达 48MPa。使用光纤和针式水听器（标称几何敏感元件直径：100 和 [公式：见文本]）测量 HITU 信号。使用光纤水听器在焦平面中进行横向扫描测量谐波径向分布。谐波径向分布可以通过高斯函数精确逼近，横向扫描与高斯拟合之间的均方根（rms）差异小于 9%，频率高达约 50MHz。高斯谐波束宽参数 σ 根据幂律随谐波数 n 变化， σ = σ/n，其中. 实验和理论空间平均滤波器之间的 rms 差异分别为 11%±1%（1.45MHz）、8%±1%（1.53MHz）和 4%±1%（3.91MHz）。对于两个更聚焦的（F/1）换能器，空间平均的影响是低估峰值压缩压力（pcp）、峰值稀疏压力（prp）和脉冲强度积分（pii）（均值±标准差）（pcp：4.9%±0.5%，prp：0.4%±0.2%，pii：2.9%±1%）和（pcp：28.3%±9.6%，prp：6%±2.4%，pii：24.3%±6.7%），分别用于 100- 和 400-[公式：见文本]-直径水听器。通过应用逆空间平均滤波器可以抑制这些误差。
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