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Spatial Sampling of Hemispherical Arrays for Three-Dimensional Photoacoustic Computed Tomography

Wanqing Zhang, Hengyue Zhu, Yide Zhang

Abstract

Three-dimensional (3D) photoacoustic computed tomography (PACT) is a powerful noninvasive biomedical imaging modality that provides volumetric data for structural and functional assessment \textit{in vivo}. To maximize angular coverage and mitigate limited-view artifacts, modern 3D PACT systems frequently employ hemispherical transducer arrays. While substantial effort has been devoted to improving image quality through post-processing algorithms, the intrinsic impact of the hardware array layout on the baseline image quality remains underexplored. In this study, we systematically investigate how the spatial sampling characteristics of hemispherical array distributions affect imaging performance under fixed hardware constraints. We propose a uniform-spacing sampling criterion to generate three representative array distributions and evaluate their performance using quantitative metrics across static, noise-perturbed, reduced-element, and rotational acquisition scenarios. Across these diverse testing regimes, the Fibonacci distribution consistently demonstrates superior structural robustness and more globally balanced reconstruction quality, a result we attribute to its highly isotropic sampling properties. These findings demonstrate that an optimal hardware-level sampling strategy is critical for maintaining global reconstruction stability. Ultimately, this framework establishes a rigorous quantitative methodology for benchmarking hemispherical array distributions and provides practical design guidance for the future development of 3D PACT systems.

Spatial Sampling of Hemispherical Arrays for Three-Dimensional Photoacoustic Computed Tomography

Abstract

Three-dimensional (3D) photoacoustic computed tomography (PACT) is a powerful noninvasive biomedical imaging modality that provides volumetric data for structural and functional assessment \textit{in vivo}. To maximize angular coverage and mitigate limited-view artifacts, modern 3D PACT systems frequently employ hemispherical transducer arrays. While substantial effort has been devoted to improving image quality through post-processing algorithms, the intrinsic impact of the hardware array layout on the baseline image quality remains underexplored. In this study, we systematically investigate how the spatial sampling characteristics of hemispherical array distributions affect imaging performance under fixed hardware constraints. We propose a uniform-spacing sampling criterion to generate three representative array distributions and evaluate their performance using quantitative metrics across static, noise-perturbed, reduced-element, and rotational acquisition scenarios. Across these diverse testing regimes, the Fibonacci distribution consistently demonstrates superior structural robustness and more globally balanced reconstruction quality, a result we attribute to its highly isotropic sampling properties. These findings demonstrate that an optimal hardware-level sampling strategy is critical for maintaining global reconstruction stability. Ultimately, this framework establishes a rigorous quantitative methodology for benchmarking hemispherical array distributions and provides practical design guidance for the future development of 3D PACT systems.
Paper Structure (16 sections, 21 equations, 11 figures)

This paper contains 16 sections, 21 equations, 11 figures.

Table of Contents

  1. Introduction
  2. Method
  3. Sampling strategy based on the uniform-spacing criterion
  4. Latitude-longitude distribution
  5. Concentric ring distribution
  6. Fibonacci distribution
  7. Evaluation metrics for distribution
  8. Numerical simulation and image reconstruction
  9. Evaluation metrics for imaging performance
  10. Experimental setup and effective system impulse response modeling
  11. Results
  12. Intrinsic characteristics and resolution analysis
  13. Static imaging performance and noise robustness
  14. Imaging performance with experimentally measured system response
  15. Dynamic imaging performance
  16. ...and 1 more sections

Figures (11)

  • Figure 1: Schematic diagram of the distribution. (a) LLD. (b) CRD. (c) FBD.
  • Figure 2: Experimentally measured system response. (a) Experimental setup. (b) Normalized time-domain signal. (c) Corresponding frequency spectrum. The solid curves and shaded areas denote the mean and STD of the measured ESIR waveforms, respectively.
  • Figure 3: Comparison of hemispherical distributions and their intrinsic spatial uniformity and periodicity. (a) 3D views of the three distributions. (b) Corresponding Voronoi cell area statistics. (c) Tangent-plane PSD.
  • Figure 4: Reconstruction of a central point target using different hemispherical distributions. (a) LLD. (b) CRD. (c) FBD. (d)–(f) PSF profile along X, Y, and Z directions, respectively. The FWHMs are shown in the legends. The scale bar is 1 cm.
  • Figure 5: Resolution variation with point source position for different hemispherical distributions. (a)–(c) Resolution measured along the axial scan. (d)–(f) Resolution measured along the radial scan. The insets are the reconstruction results of three distributions.
  • ...and 6 more figures