超声波色差对二次谐波成像影响的研究

为了分析超声波中色差对二次谐波成像的影响,通过理论分析和仿真实验研究组织谐波成像中的色差问题.仿真结果显示,在有色差存在的情况下,二次谐波的能量产生主要集中在近场附近,谐波声束剖面与色差的基波相似,尽管二次谐波是在较深的深度产生的,它仍然会经历较大的色差,背散射声束在经过体壁传输时会使脉冲产生更严重的色差,并且随着频率的增加,非线性部分平滑振幅波动的能力减弱,从而使得色差幅度更严重.

Ultrasonic wave aberration effect on second harmonic imaging

The theory analysis and simulations were conducted to explain how the ultrasonic wave aberration affects second harmonic imaging in medical ultrasonic diagnosis. Simulation results indicate that in the case of aberration, the energy of second harmonic is mainly generated in the near field and the profile of second harmonic is nearly the same as the fundamental. Though second harmonic is generated deeply, it experiences serious aberration. When the back scattering acoustic beam goes through body wall, it makes pulse to generate worse aberration. The ability of nonlinear amplitude fluctuation is weakened and the aberration’s amplitude is larger with the increase of frequency.