Accurate visualization of the focal spot in high-intensity focused ultrasound (HIFU) is essential for safe and effective therapeutic guidance. Passive acoustic mapping (PAM) provides a noninvasive method for reconstructing acoustic fields from scattered signals generated as HIFU pulses interact with tissue inhomogeneities. This study introduces a synthetic aperture strategy for three-dimensional beam reconstruction by mechanically rotating a one-dimensional linear ultrasound probe. Five synthetic configurations were assessed: 1D Linear, Cross Linear, Discrete Annular, Random Sparse, and Fibonacci Spiral. Each was formed by rotating a 64-element probe at predefined angles. A Full Aperture Array was included as a reference baseline. The Fibonacci Spiral Array achieved the most balanced performance among the synthetic configurations, combining high structural similarity (SSIM = 0.711 in X-Y) with strong sidelobe suppression (PSL = -12.538 dB in Y-Z), low mean squared error, and consistently high output quality across all evaluated planes. These results closely matched those of the Full Aperture Array, supporting similar resolution and localization accuracy. These findings indicate that spiral-based sampling provides a hardware-efficient, high-fidelity solution for volumetric PAM in therapeutic ultrasound, offering a practical alternative to conventional two-dimensional matrix arrays.
Kang et al. (Mon,) studied this question.