The influences of finite aperture size in photoacoustic computed tomography

Xiaofei Luo; Jinsheng Jiang; Hualin Wu; Minhao Li; Bo Wang

doi:10.1016/j.ultras.2023.107042

The influences of finite aperture size in photoacoustic computed tomography

Ultrasonics. 2023 Aug:133:107042. doi: 10.1016/j.ultras.2023.107042. Epub 2023 May 12.

Authors

Xiaofei Luo¹, Jinsheng Jiang¹, Hualin Wu², Minhao Li¹, Bo Wang³

Affiliations

¹ Department of Biomedical Engineering, School of Basic Medical Science, Central South University, Changsha, Hunan 410083, China.
² College of Mechanical and Electrical Engineering, Central South University, Changsha, Hunan 410083, China.
³ Department of Biomedical Engineering, School of Basic Medical Science, Central South University, Changsha, Hunan 410083, China. Electronic address: lrain32@csu.edu.cn.

PMID: 37186987
DOI: 10.1016/j.ultras.2023.107042

Abstract

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.

Keywords: Acoustic field; Back-projection method; Finite aperture effect; Photoacoustic computed tomography; Spatial aliasing.