Three-Dimensional Passive Acoustic Mapping of High Intensity Focused Ultrasound Fields Using Sparse Synthetic Apertures from Rotated One-Dimensional Linear Arrays

Accurate visualization of the focal spot in high-intensity focused ultrasound (HIFU) is essential for safe and effective therapeutic guidance. Passive acoustic mapping (PAM) offers a noninvasive approach by reconstructing acoustic fields from scattered signals generated as the HIFU pulse interacts with tissue inhomogeneities. In this study, we propose a synthetic aperture strategy that reconstructs three-dimensional HIFU beam profiles by mechanically rotating a one-dimensional linear ultrasound probe. Five synthetic configurations were evaluated: linear, cross-linear, discrete annular, random sparse, and Fibonacci spiral. Each was formed by rotating a 64-element probe at predefined angles to simulate volumetric sampling. Among them, the Fibonacci spiral provided the most uniform spatial coverage with minimal redundancy. Numerical simulations were performed to compare volumetric beam reconstructions based on spatial resolution, localization error, structural similarity, and sidelobe suppression. The Fibonacci spiral configuration achieved the closest match to the ground truth, with the highest structural similarity index, the lowest peak sidelobe level (− 11.17 dB), and submillimeter localization accuracy. These findings suggest that the proposed spiral-based sampling method enables high-fidelity and cost-effective monitoring of therapeutic ultrasound fields and represents a practical alternative to conventional two-dimensional matrix arrays for volumetric beam visualization.