中文摘要：

基于超声波在生物软组织中的传播机理,研究聚焦超声换能器焦区内软组织超声背散射信号中心频率的偏移量与组织超声特征散射子粒径的相关性。通过计算机模拟实验,探讨了组织的衰减系数和超声特征散射子的数浓度（单位体积内散射子的个数）以及换能器的中心频率、带宽和聚焦性等参数对频移量的影响。模拟结果表明,换能器焦区内软组织超声背散射信号中心频率的偏移量随散射子粒径的增大而增加,近似呈线性增长的关系;偏移量与组织的衰减系数和发射换能器的中心频率、带宽等参数有关,这些参数越大,偏移量也越大;散射子的数密度、聚焦超声换能器的聚焦性等参数对频移量的影响不大。

英文摘要：

Based on the principle of ultrasonic propagation in biological soft tissues,we studied the relationship between the central frequency offset of ultrasonic backscattered signals and the scatterer size of tissues in focal region of focal ultrasonic transducer.We utilized the computer simulation to explore the effect on the central frequency shift by the attenuation coefficient and the number concentration of scatterers（the numbers of scatterer per unit volume） of soft tissues,the central frequency and the bandwidth and the focal property of ultrasonic transducer.The simulation results reveal that the frequency shift of ultrasonic backscattered signal from soft tissues increases approximately linearly with the size of scatterers.The frequency offsets are related to the attenuation coefficients of tissues and the central frequency and the bandwidth of the launch transducer.The offset increases with the augmentation of these parameters.While the concentration of scatterers and focal parameters of focal ultrasonic transducer have little influence on the frequency offset.