Author: Leshan Sun, Liangzhong Xiang, Yifei Xu, Yuchen Yan 👨🔬
Affiliation: University of California, Irvine 🌍
Purpose: X-ray Acoustic Computed Tomography (XACT) is a transformative innovation in medical imaging, overcoming the limitations of conventional X-ray techniques. It introduces new possibilities in clinical applications such as radiation therapy monitoring, interventional radiology, and non-destructive evaluations. This study presents 2D and 3D XACT imaging using a linear array(2D) and a matrix array(3D) , demonstrating its capabilities on dynamic and fast medical imaging potentials.
Methods: X-ray pulses with a 50-nanosecond pulse width, emitted by a portable X-ray device (25 Hz repetition rate, Golden Engineering Inc.), generating pressure waves known as X-ray Acoustic (XA) signals. A linear ultrasound transducer (L12-5L40N-4, 5–12 MHz, 39 mm field of view, TELEMED Co.) with 128 elements was employed for simultaneous 2D XA and ultrasound imaging. Additionally, a 3D ultrasound transducer (1 MHz, Doppler Co.) with a 16×16 matrix array enabled 3D XA imaging of therapeutic needles. Image reconstruction was performed using Model-Based XACT back-projection combined with iterative regularized LSQR (Model-Based LSQR) algorithms.
Results: Using a 2D linear array, the XACT system successfully captured simultaneous XA and ultrasound images with a spatial resolution of ~0.3 mm, effectively tracking needle movement. In addition, 3D XA imaging was achieved using the matrix array, with a resolution of ~3 mm. The current frame rate, approximately 0.5 seconds per frame, is influenced by signal-to-noise ratio (SNR) and X-ray pulse repetition rates. These results demonstrate XACT’s potential for real-time monitoring of needle positioning during therapeutic interventions.
Conclusion: The XACT system combines low-radiation, high-contrast XA imaging with ultrasound imaging, enabling the visualization of therapeutic needles, contrast agents, and surrounding tissues. Enhancements in XACT technology—such as higher-energy X-ray pulses and more sensitive ultrasound probes with broader bandwidths—could further improve its performance. Future in vivo studies are required to validate the system's efficacy in real tissue environments and advance its clinical utility.