C-arm inverse geometry CT for 3D cardiac chamber mapping

Abstract: Image-guided navigation of catheter devices to anatomic targets within large 3D cardiac chambers and vessels is challenging in the interventional setting due to the limitations of a conventional 2D x-ray projection format. Scanning-beam digital x-ray (SBDX) is a low-dose inverse geometry x-ray fluoroscopy technology capable of real-time 3D catheter tracking. SBDX performs rapid tomosynthesis using an electronically scanned multisource x-ray tube and photon-counting detector mounted to a C-arm gantry. However, SBDX currently lacks the ability to perform volumetric computed tomography from a rotational C-arm scan. This work develops a novel volumetric CT capability for the SBDX platform, termed C-arm inverse geometry CT, suitable for rotational scans of the beating heart. The work is divided into three tasks: development of image reconstruction algorithms, implementation on the SBDX hardware, and performance assessment for the example task of 3D cardiac chamber mapping. SBDX-CT data acquisition is performed by simultaneous x-ray source scanning at 15 scan/s and C-arm rotation over a 190 degree short-scan arc in 13.4 seconds. An iterative reconstruction method was developed to accommodate fully truncated projections and data inconsistency resulting from cardiac motion during rotation. Hardware implementation included development of a C-arm angle measurement method, development of a geometric calibration method to account for non-ideal C-arm rotations, and detector response nonlinearity correction. The geometric calibration procedure mitigated artifacts from C-arm deflection during rotation. SBDX-CT image quality was evaluated in phantom studies. Feasibility of in-vivo SBDX-CT was demonstrated in a porcine model.