频域法超声逆散射成像

Frequency Domain Method for Ultrasound Diffraction Tomography

研究了二维理想情况下,基于Fourier散射投影定理的超声逆散射成像问题。分析了分辨率与成像质量的关系,给出了扫描步长满足的必要条件,进一步降低了存储量及运算复杂度。不同于基于NUFFT的迭代型超声逆散射图像重建法,本文提出一种基于NUFFT的插值法,利用均匀网格最邻近的两条投影线上的非均匀样点进行线形角度插值。并引入了正则化的谱外推法,用于提高图像的分辨率。仿真实验表明,重建效果远远优于滤波反投影法。随着投影数的增加,重建的像函数将趋于最优。

Problem of 2-D ultrasound diffraction tomography based on Fourier scattering theorem of the lossless circumstance is presented. The relation between resolution and imaging quality is analyzed, the essential condition of scanning step is discussed, a recon- struction algorithm in frequency domain of discrete signal is proposed to reduce storage and computation. Different from an iterative re- construction method based on NUFFT, we put forward a novel algorithm of interpolation using NUFF1~, which compute the equispaced re- suits from the non-uniform samples of two nearest projection lines using linear angular interpolation. We also introduce the regularization spectrum extrapolation to improve imaging resolution. The simulation result indicates that the algorithm proposed in this paper is much better than filtered back-projection algorithm. With the projection data increase, reconstruction will approximate to the optimal.