Purpose: Intraoperative 3D-CBCT imaging is revolutionizing orthopedic interventions. A critical barrier to treatment efficacy, however, is the longitudinal and lateral field-of-view. Here, we look to overcome field-of-view limitations by developing and investigating a continues dual-isocenter 3D-CBCT imaging acquisition, potentially enabling intraoperative assessment and procedural verification of long and wide anatomical sites.
Methods: To image from the hip to the feet of a whole-body phantom, a continuous dual-isocenter acquisition was implemented on a clinical robotic CBCT system. The imaging trajectory was composed of 2 × 200° circular arcs separated by alternating lateral and longitudinal table translations. Rotation (clockwise/anticlockwise) and table translation (left/right) was reversed every 400° due to hardware rotation constraints. Longitudinal table translation was always away from the gantry. The gantry/table movements were repeated 7 times, with projections continuously acquired at 15 frames/second. As comparator, conventional large volume scans were acquired and stitched together. Root Mean Square Deviation (RMSD), Mean Absolute Percentage Deviation (MAPD), Structural Similarity Index Metric (SSIM) and Contrast-to-Noise Ratio (CNR) were used for image quality quantification.
Results: The continuous dual-isocenter acquisition enabled image dimensions of L = 95 cm x W = 44 cm x H = 24 cm, capturing the hips to the feet in half the imaging dose and acquisition time of the 11 stitched conventional scans required to match the image dimensions. Compared to the stitched conventional images, the dual isocenter scan had RMSD of 4.84, MAPD of 6.58% and SSIM of 0.99. The dual isocenter image had CNR of 1.998 while the stitched conventional had CNR of 1.999.
Conclusion: Continuous dual-isocenter imaging was successfully implemented on a clinical robotic CBCT system, extending both the longitudinal and lateral CBCT field-of-view. This technological advance will allow improved management of patients via providing intraoperative assessment of long and wide anatomical sites.
Funding Support, Disclosures, and Conflict of Interest: DISCLAIMER: This research was supported by a Siemens grant. The concept and information presented in this paper are based on research and is not commercially available. Due to regulatory reasons its future availability cannot be guaranteed.