Department of Electronic and Communication Engineering, North China Electric Power University, Baoding 071003, China.
Hebei Key Laboratory of Power Internet of Things Technology, North China Electric Power University, Baoding 071003, China.
Exp Biol Med (Maywood). 2022 Jun;247(11):881-897. doi: 10.1177/15353702221079570. Epub 2022 Mar 1.
In photoacoustic tomography (PAT), conventional image reconstruction methods are generally based on the assumption of an ideal point-like ultrasonic detector. This assumption is appropriate when the receiving surface of the detector is sufficiently small and/or the distance between the imaged object and the detector is large enough. However, it does not hold in endoscopic applications of PAT. In this study, we propose a model-based image reconstruction method for endoscopic photoacoustic tomography (EPAT), considering the effect of detector responses on image quality. We construct a forward model to physically describe the imaging process of EPAT, including the generation of the initial pressure due to optical absorption and thermoelastic expansion, the propagation of photoacoustic waves in tissues, and the acoustic measurement. The model outputs the theoretical sampling voltage signal, which is the response of the ultrasonic detector to the acoustic pressure reaching its receiving surface. The images representing the distribution map of the optical absorption energy density on cross-sections of the imaged luminal structures are reconstructed from the sampling voltage signals output by the detector through iterative inversion of the forward model. Compared with the conventional approaches based on back-projection and other imaging models, our method improved the quality and spatial resolution of the resulting images.
在光声断层扫描（PAT）中，传统的图像重建方法通常基于理想点式超声探测器的假设。当探测器的接收面足够小和/或成像物体与探测器之间的距离足够大时，这种假设是合适的。然而，在 PAT 的内窥镜应用中，这种假设并不成立。在这项研究中，我们提出了一种基于模型的内窥镜光声断层扫描（EPAT）图像重建方法，考虑了探测器响应对图像质量的影响。我们构建了一个正向模型来物理描述 EPAT 的成像过程，包括由于光吸收和热弹性膨胀而产生的初始压力、光声波在组织中的传播以及声学测量。该模型输出理论采样电压信号，即超声探测器对到达其接收面的声压的响应。通过对正向模型的迭代反演，从探测器输出的采样电压信号中重建代表成像腔道结构横截面处光吸收能量密度分布图的图像。与基于反向投影和其他成像模型的传统方法相比，我们的方法提高了所得图像的质量和空间分辨率。
