用于乳腺超声透射断层成像的飞行时间精确计算方法

目的:针对乳腺超声透射断层成像（UTCT）,提出一种精确计算超声波飞行时间（TOF）的方法,实现定量乳腺声速图像的高质量重建。方法:利用k-wave平台设置超声透射断层扫描环境,获取两种不同复杂度的数字乳腺体模的扫描数据,分别使用提出的极值点法及常用的阈值法、过零点法和峰值法计算出TOF,并借助滤波反投影算法重建声速图像。结果:峰值法计算出的TOF难以重建出完整的声速图像,极值点法重建出的声速图像在均方根误差（RMSE）和结构相似性指标（SSIM）上均优于阈值法和过零点法,相比于阈值法和过零点法,RMSE平均减小了8.025%、1.643%, SSIM平均增加了1.708%、1.68%。结论:本文提出的极值点法能够精确计算出TOF,有助于UTCT进行高质量的声速图像重建。

Accurate calculation method of time of flight for breast ultrasound transmission tomography

Objective Aiming at ultrasound transmission tomography (UTCT) of breast , a method for accurately calculating ultrasonic time-of-flight (TOF) was proposed to achieve high-quality reconstruction of quantitative breast sound -speed image. Methods The UTCT scanning environment was set up by k-wave platform to obtain the scanning data of two kinds of digital breast phantoms with different complexity. The extreme-point method and the commonly used threshold method, zero-crossing method and peak method were respectively used to calculate TOF, and the sound-speed image was reconstructed by filtering back-projection algorithm . Results The TOF calculated by the peak method cannot reconstruct the complete sound-speed image . The sound-speed image reconstructed by the extreme point method proposed in this paper is superior to the other two methods in root mean square error (RMSE) and structural similarity index (SSIM), compared with the threshold method and the zero-crossing method, the RMSE of the extreme point method is reduced by 8.025% and 1.643% on average, the SSIM is increased by 1.708% and 1.68% on average. Conclusion The extreme-point method can accurately calculate TOF, which is helpful for obtaining high-quality sound-speed images in UTCT scanning