光声层析成像的信号处理

报道了采用滤波反投影的光声层析成像的信号处理方法，为了还原空间位置的光声信号，声探测器接收到的光声信号和探测器的脉冲响应在频域进行逆卷积处理；由于光声信号相对于触发时刻的延迟时间就是光声源到探测器的走时，重建时根据光声信号的延迟时间以及声速的距离，把速度势信号反投影到与探测器等距离的圆弧上。通过多个角度的反投影，能够重建出光声源的图像，但是由于反投影时光声信号投影到没有光声源的地方产生伪迹信号，模糊了光声源图像的边界，降低了图像的分辨率和对比度。因此在反投影之前采用CT成像中的R-T空间滤波函数与光声速度势信号进行卷积处理，然后再进行反投影成像；这种方法降低了由反投影带来的伪迹。应用这些处理方法，获得了埋藏深度为12mm的四个光吸收体的二维光声层析成像。

Signal Process of Photoacoustic Tomography

A method of photoacoustic (PA) tomography with the filtered back projection is proposed. For the PA signals of the source, real PA pressures are obtained by deconvoluting the impulse response of the transducer used for detecting the PA signals of samples. The optical absorption distributions of the samples are reconstructed using the filtered back projection with sufficient PA pressures in different directions. The data are filtered with SL (Slion-Line) filter before back projecting. Simulations and experiments were performed to compare the filtered back projection and the direct back projection. The results prove the filtered back projection method is valid for PA imaging. Combining this image method, the two-dimension PA images of four absorbers buried in 12 mm were reconstructed.