Calibration and use of intraoperative cone-beam computed tomography: an in-vitro study for wrist fracture.

The standard workflow in many image-guided procedures, preoperative imaging followed by intraoperative registration, can be a challenging process and is not readily adaptable to certain anatomical regions such as the wrist. In this study we present an alternative, consisting of a preoperative registration calibration and intraoperative navigation using 3D cone-beam CT. A custom calibration tool was developed to preoperatively register an optical tracking system to the imaging space of a digital angiographic C-arm. This preoperative registration was then applied to perform direct navigation using intraoperatively acquired images for the purposes of an in-vitro wrist fixation procedure. A validation study was performed to assess the stability of the registration and found that the mean registration error was approximately 0.3 mm. When compared to two conventional techniques, our navigated wrist repair achieved equal or better screw placement, with fewer drilling attempts and no additional radiation exposure to the patient. These studies suggest that preoperative registration coupled with direct navigation using procedure-specific graphical rendering, is potentially a highly accurate and effective means of performing image-guided interventions.