An on-board surgical tracking and video augmentation system for C-arm image guidance

• Published in: International journal for computer assisted radiology and surgery 2012-09, Vol.7 (5), p.647-665
• Main Authors: Reaungamornrat, S., Otake, Y., Uneri, A., Schafer, S., Mirota, D. J., Nithiananthan, S., Stayman, J. W., Kleinszig, G., Khanna, A. J., Taylor, R. H., Siewerdsen, J. H.
• Format: Article
• Language: English
• Subjects: Computer Imaging; Computer Science; Cone-Beam Computed Tomography; Equipment Design; Fluoroscopy; Health Informatics; Humans; Imaging; Imaging, Three-Dimensional; Medicine; Medicine & Public Health; Original Article; Pattern Recognition and Graphics; Radiographic Image Enhancement - instrumentation; Radiographic Image Interpretation, Computer-Assisted - methods; Radiology; Surgery; Surgery, Computer-Assisted - instrumentation; Vision; X-Ray Intensifying Screens
• ISSN: 1861-6410; 1861-6429
• DOI: 10.1007/s11548-012-0682-9

Purpose Conventional tracker configurations for surgical navigation carry a variety of limitations, including limited geometric accuracy, line-of-sight obstruction, and mismatch of the view angle with the surgeon’s-eye view. This paper presents the development and characterization of a novel tracker configuration (referred to as “Tracker-on-C”) intended to address such limitations by incorporating the tracker directly on the gantry of a mobile C-arm for fluoroscopy and cone-beam CT (CBCT). Methods A video-based tracker (MicronTracker, Claron Technology Inc., Toronto, ON, Canada) was mounted on the gantry of a prototype mobile isocentric C-arm next to the flat-panel detector. To maintain registration within a dynamically moving reference frame (due to rotation of the C-arm), a reference marker consisting of 6 faces (referred to as a “hex-face marker”) was developed to give visibility across the full range of C-arm rotation. Three primary functionalities were investigated: surgical tracking, generation of digitally reconstructed radiographs (DRRs) from the perspective of a tracked tool or the current C-arm angle, and augmentation of the tracker video scene with image, DRR, and planning data. Target registration error (TRE) was measured in comparison with the same tracker implemented in a conventional in-room configuration. Graphics processing unit (GPU)-accelerated DRRs were generated in real time as an assistant to C-arm positioning (i.e., positioning the C-arm such that target anatomy is in the field-of-view (FOV)), radiographic search (i.e., a virtual X-ray projection preview of target anatomy without X-ray exposure), and localization (i.e., visualizing the location of the surgical target or planning data). Video augmentation included superimposing tracker data, the X-ray FOV, DRRs, planning data, preoperative images, and/or intraoperative CBCT onto the video scene. Geometric accuracy was quantitatively evaluated in each case, and qualitative assessment of clinical feasibility was analyzed by an experienced and fellowship-trained orthopedic spine surgeon within a clinically realistic surgical setup of the Tracker-on-C. Results The Tracker-on-C configuration demonstrated improved TRE (0.87 ± 0.25) mm in comparison with a conventional in-room tracker setup (1.92 ± 0.71) mm ( p