Correction of patient motion in cone-beam CT using 3D-2D registration

• Published in: Physics in medicine & biology 2017-11, Vol.62 (23), p.8813-8831
• Main Authors: Ouadah, S, Jacobson, M, Stayman, J W, Ehtiati, T, Weiss, C, Siewerdsen, J H
• Format: Article
• Language: English
• Subjects: 3D-2D registration; Algorithms; C-arm; Calibration; Cone-Beam Computed Tomography; cone-beam CT; Humans; image quality; image-guided interventions; Imaging, Three-Dimensional - methods; motion artifact; motion correction; Movement; Phantoms, Imaging
• ISSN: 0031-9155; 1361-6560; 1361-6560
• DOI: 10.1088/1361-6560/aa9254

Cone-beam CT (CBCT) is increasingly common in guidance of interventional procedures, but can be subject to artifacts arising from patient motion during fairly long (~5-60 s) scan times. We present a fiducial-free method to mitigate motion artifacts using 3D-2D image registration that simultaneously corrects residual errors in the intrinsic and extrinsic parameters of geometric calibration. The 3D-2D registration process registers each projection to a prior 3D image by maximizing gradient orientation using the covariance matrix adaptation-evolution strategy optimizer. The resulting rigid transforms are applied to the system projection matrices, and a 3D image is reconstructed via model-based iterative reconstruction. Phantom experiments were conducted using a Zeego robotic C-arm to image a head phantom undergoing 5-15 cm translations and 5-15° rotations. To further test the algorithm, clinical images were acquired with a CBCT head scanner in which long scan times were susceptible to significant patient motion. CBCT images were reconstructed using a penalized likelihood objective function. For phantom studies the structural similarity (SSIM) between motion-free and motion-corrected images was  >0.995, with significant improvement (p