基于不同频率成份衰减矫正的光声成像方法

根据超声衰减理论,研究了光声信号不同频率成份随距离的衰减差异,及其对光声图像重建的影响;提出了对光声信号不同频率成份进行衰减矫正的成像方法,此方法增强了光声信号的高频成份,突出了吸收体的边界变化和细微的结构特征,提高了成像系统分辨率,实验结果显示系统分辨率由0.3 mm提高到0.2 mm.实验所用的光源为YAG激光器,波长为1064 nm,重复频率为20 Hz,脉宽为6 ns,探测器为针状的PVDF膜水听器,接收面积的直径为1 mm.

Photoacoustic Imaging with Attenuation Rectification of Different Frequent Components of Photoacoustic Signal

The influences of attenuation coefficients of photoacoustic signals, which depends on frequencies, on the quality of reconstructed photoacoustic images has been explored. It reveals that the attenuation coefficients of low frequent components are less than those of high frequencies, and the latter are more important for photoacoustic imaging with high resolution. Based on the ultrasonic attenuation theory, the method of photoacoustic imaging with rectification of the attenuation of different frequent component was performed. The experiments results show that this method improves the resolution of reconstructed images, and the reconstructed images resolution improved from 0.3 mm to 0.2 mm. A Q-switched Nd:YAG laser operating at 1064 nm was used as light source. The laser had a pulse width of 6ns and a repetition frequency of 20 Hz. A needle PVDF hydrophone with diameter of 1 mm was used to detect photoacoustic signals.