摘要:
为了提高相位畸变条件下的医学超声成像的横向分辨率和对比度,提出了一种利用回波信号相干性的校正方法。首先给出平均相干系数的概念,并将其作为相位误差校正的度量,然后通过最大化平均相干系数逐步校正各个通道的延时误差,最后再利用经过校正的数据计算出一组新的相干系数并对回波信号进行加权优化,从而得到最终用于成像的数据。对点散射目标及斑散射目标的仿真结果分别显示,利用所提出的方法横向分辨率提高了约0.24 mm,对比度提高了约18 dB,且要优于邻近阵元互相关方法和相干系数直接加权的处理方法。利用回波相干性的相位畸变校正方法结合了相位误差校正和加权处理的优点,可以有效地改善医学超声成像的质量。
Abstract:
In order to improve the lateral resolution and enhance the contrast of medical ultrasound imaging in the presence of phase aberration,a coherence-based correction method was proposed.The averaged coherence factor was proposed at first and used as a metric to evaluate phase aberration correction.By maximizing the averaged coherence factor,the time delay parameter of each channel was adjusted.Then a new set of coherence factors was calculated with the corrected data.And finally the corrected data was optimized by the coherence factors to form a B-mode image.The simulations on point targets and a cyst phantom showed that the proposed method outperformed the nearest-neighboring cross-correlation method and conventional coherence-weighting method,and the lateral resolution and contrast ratio was improved by approximately 0.24 mm and 18 dB respectively.The proposed method combined the advantages of phase error correction and coherence-weighting,which could improve imaging qualities effectively in medical ultrasound.
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