Department of Biomedical Engineering, School of Basic Medical Science, Central South University, Changsha, Hunan 410083, China.
College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan 410083, China.
Ultrasonics. 2023 Aug;133:107042. doi: 10.1016/j.ultras.2023.107042. Epub 2023 May 12.
In photoacoustic computed tomography (PACT), the "finite aperture effect" is often characterized as a tangential resolution that increases proportionally with the distance from the rotation center. However, this conclusion is based on the inaccurate point-detector assumption used in image reconstruction. In this study, we appropriately modeled the finite size of the acoustic detector in the back-projection (BP) based image reconstruction to improve the accuracy of the time delay calculation and systematically investigated its effects. Our results showed that the main effect of the finite aperture size is the creation of a limited high-quality imaging region (HQIR) around the scanning center, due to the directional sensitivity of the detector. We also demonstrated that the "finite aperture effect" can reduce the optimal number of detectors required for spatial anti-aliasing. These new findings provide novel perspectives for optimizing PACT systems and corresponding reconstruction methods.
在光声计算机断层扫描（PACT）中，“有限孔径效应”通常被描述为与旋转中心距离成正比的切向分辨率。然而，这一结论是基于图像重建中使用的不准确的点探测器假设。在这项研究中，我们在基于反向投影（BP）的图像重建中适当地模拟了声学探测器的有限尺寸，以提高时间延迟计算的准确性，并系统地研究了其影响。研究结果表明，由于探测器的方向灵敏度，有限孔径尺寸的主要影响是在扫描中心周围创建一个有限的高质量成像区域（HQIR）。我们还证明，“有限孔径效应”可以减少空间反走样所需的最佳探测器数量。这些新发现为优化 PACT 系统和相应的重建方法提供了新的视角。
