声衍射层析成像中吸收型散射体的Rytov二阶近似重建

ACOUSTICAL TOMOGRAPHY FOR ABSORBING SCATTERERS BASED ON THE SECOND-ORDER RYTOV TRANSFORM PERTURBATION APPROXIMATION

文中详细讨论了Rytov二阶近似下的声逆散射微扰论公式 ,并考察了它的适用范围 .介绍了吸收型散射体的Rytov二阶近似重建算法 ,重建了散射体内部的波数和吸收系数 .这种散射体的重建与纯位相型散射体的重建一样 ,不同的只是在计算正散射时考虑了吸收的影响 .数值模拟给出了Born一阶、二阶和Rytov一阶、二阶近似重建的例子 。

In this paper, a reconstruction algorithm of acoustical tomography is presented for absorbing scatterers based on the second order Rytov transform perturbation approximation. Both the wave number and the absorbing coefficient of the scatterers are reconstructed. The reconstruction algorithm is similar to one for phase scatterers, but the computation of the direct scattering is different, because the attenuation must be calculated. A comparison of some reconstruction algorithms is also given, such as those based on the first and second order Born approximations and those based on the first and second order Rytov approximations. The results show that the algorithm based on the second order Rytov approximation has an advantage over the other three algorithms in the most cases.