XACT-guided interventional procedures: A feasibility study

X-ray Induced Acoustic Computed Tomography (XACT) is an emerging imaging technique that provides 3D volumetric images from a single projection by detecting X-ray-induced acoustic (XA) waves with ultrasound (US) transducers. Unlike MRI or CT, XACT enables real-time 3D imaging without long acquisition times, 2D limitations, or motion artifacts from mechanical rotation. Furthermore, when integrated with conventional pulse-echo US through time-sequenced operation, XACT provides complementary soft-tissue contrast, establishing it as a promising platform for dynamic interventional radiology (IR) guidance.

This study aims to evaluate the feasibility of XACT as a novel imaging tool for IR, specifically for guiding needle placement and monitoring contrast agent dynamics.

We developed a 3D XACT imaging system equipped with a 256-element 2D matrix array and a portable X-ray tube to visualize needle insertion and contrast agent dynamics. To capture both needle position and soft tissue anatomy, we integrated a dual-modality system combining XACT with pulse-echo US using a 128-element linear US array. Experiments were conducted on both tissue-mimic phantoms and soft tissue samples. GPU-accelerated algorithm has been developed for 3D XACT image reconstruction.

The results demonstrate the 3D capabilities of XACT imaging for interventional procedures, including monitoring of needle placement and tracking of contrast agent dynamics. The imaging speed reached up to 3∼4 s per frame, constrained by the repetition rate of the X-ray source and signal to noise ratio. The dual-modality approach provided clear visualization of the needle's position and the surrounding soft tissue structures, achieving imaging resolution around 2 mm.

This study demonstrates that XACT imaging is feasible to be used for IR. Its 3D imaging capability with faster imaging speed would be an alternative to cone beam CT and its capability to combine US imaging will provide richer information for soft tissue.