Objectives: To describe our preclinical experience with Cone Beam CT (CBCT) in image-guided surgery of the temporal bone. Study design and settings: A mobile isocentric C-arm (PowerMobil, Siemens Medical Systems, Erlangen, Germany) modified to include a flat-panel detector (Varian Imaging Products, Palo Alto, CA) and a motorized orbit was developed to acquire multiple projections in rotation about a subject. Initial experiments imaging steel wire in air were used to investigate the system's spatial resolution in 3D image reconstruction. Subsequently temporal bone dissection was performed on five cadaver heads using the modified C-arm as an image guidance system. Results: We obtained a spatial resolution of 0.85 mm. The image acquisition time was 120 seconds and the radiation dose approximately one-tenth of a conventional CT scan. Conclusion: CBCT provided submillimeter accuracy at high speed with low radiation dosage to offer utility as an intraoperative imaging system. Significance: CBCT offers technology that approximates "near-real-time" image guidance. EBM rating: C-4.
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