Article
Reduction of radiation in minimally invasive pedicle screw placement with a robotic system and 3D fluoroscopy
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Published: | June 18, 2018 |
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Objective: Evaluating the feasibility of referencing a robotic system with a 3D fluoroscopy instead of computed tomography (CT) for the minimally invasive placement of pedicle screws in the thoracolumbar spine. Accuracy of the pedicle screws were measured and compared with the amount of radiation of CT and fluoroscopy.
Methods: In three frozen cadavers 12 pedicle screws were implanted minimally invasively (Viper, Depuy Synthes, Zuchwil, Switzerland) in segments T10 to L1 with the Robotic Surgery Assistant (ROSA One, Zimmer-Biomet Robotics, Montpellier, France). Referencing was performed with 3D fluoroscopy (Ziehm Vision RFD 3D, Ziehm Imaging, Nürnberg). Postoperative position of screws was identified on 3D fluoroscopy and compared to planned trajectories. Pedicle screws were graded as: Grade 1: screw completely within pedicle, Grade 2: screw less than 2 mm outside, Grade 3: screw is over 2mm outside, Grade 4A: screw is inside the spinal canal, Grade 4B: screw is outside the vertebra. Radiation was measured as Computed Tomography Dose Index (CTDI) with a 3-part polymethyl-methacrylate (PMMA) phantom (IBA Dosimetry, Schwarzenbruck) using a CT scan (Ingenuity 128, Philips Healthcare, Amsterdam, Netherlands) and the Ziehm Vision 3D fluoroscopy.
Results: Eleven of 12 screws were rated as Grade 1, one screw as Grade 2. Radiation exposure amounted to CTDIW 25.6 mGy in CT and 17.2 mGy in fluoroscopy, resulting in a radiation reduction of 33%.
Conclusion: Robot-guided minimally invasive pedicle screw implantation, using 3D-fluoroscopy for referencing, is a reliable method which can reduce radiation exposure.