Orthopaedic surgeons are still following the decades old workflow of using dozens of two-dimensional fluoroscopic images to drill through complex 3D structures, e.g. pelvis. This Letter presents a mixed reality support system, which incorporates multi-modal data fusion and model-based surgical tool tracking for creating a mixed reality environment supporting screw placement in orthopaedic surgery. A red-green-blue-depth camera is rigidly attached to a mobile C-arm and is calibrated to the cone-beam computed tomography (CBCT) imaging space via iterative closest point algorithm. This allows real-time automatic fusion of reconstructed surface and/or 3D point clouds and synthetic fluoroscopic images obtained through CBCT imaging. An adapted 3D model-based tracking algorithm with automatic tool segmentation allows for tracking of the surgical tools occluded by hand. This proposed interactive 3D mixed reality environment provides an intuitive understanding of the surgical site and supports surgeons in quickly localising the entry point and orienting the surgical tool during screw placement. The authors validate the augmentation by measuring target registration error and also evaluate the tracking accuracy in the presence of partial occlusion.
Keywords: 3D point clouds; CBCT imaging; adapted 3D model-based tracking algorithm; automatic tool segmentation; bone; complex 3D structures; computerised tomography; cone-beam computed tomography imaging space; diagnostic radiography; entry point; image fusion; image reconstruction; image registration; image segmentation; interactive 3D mixed reality environment; iterative closest point algorithm; iterative methods; medical image processing; mixed reality environment; mixed reality visualisation; mobile C-arm; model-based surgical tool tracking; multimodal data fusion; multimodal imaging; orthopaedic surgery; orthopaedics; partial occlusion; pelvis; real-time automatic fusion; reconstructed surface; red-green-blue-depth camera; screw placement; surgery; surgical tools; synthetic fluoroscopic images; target registration error; tracking accuracy; two-dimensional fluoroscopic images; workflow.