声速不均匀介质的光声成像重建算法

Reconstruction Algorithm of Photoacoustic Tomography with Acoustic Speed Heterogeneity

为提高声速不均匀介质的光声成像精度,提出一种基于反卷积的光声成像重建算法。本算法不需预先知道介质的声速分布。先通过探测到的光声信号构造出一个新函数,并用不同位置探测到的光声信号间的相关性来估计空间两点间的声波传播时间,以补偿声速的不均匀性。然后基于反卷积方法由该函数解出待测组织内的电磁波吸收分布。仿真研究结果表明,当介质声速差异在10%以内时,重建图像能正确反映待测目标的大小、位置和电磁波吸收系数,算法具有良好的抗噪性能。由于生物软组织内的声速差异一般小于10%,因此本算法是一种有效的光声成像重建算法。

A deconvolution-based reconstruction algorithm is proposed to enhance the precision of the photoacoustic tomography （PAT） with the acoustic heterogeneity. This algorithm does not require the prior knowledge of the acoustic speed distribution. Firstly, a new function was constructed from detected photoacoustic signals, while the correlation between photoacoustic signals was employed to estimate the flight time of acoustic waves between two spatial positions and compensate the acoustic heterogeneity. Then the electromagnetic absorption distribution of the detected tissue can be reconstructed from this new function based on the deconvolution method. It is shown by simulation results that the reconstructed image can correctly indicate the size, location and electromagnetic absorption coefficient of detected objects when the acoustic speed variation is within 10%. This algorithm has a strong robustness to the noise. Since the acoustic speed variation of biological soft tissues is normally lower than 10 %, this algorithm is an efficient reconstruction algorithm for the PAT.