Study design: In-vitro radiation exposure study.
Objective: To determine the radiation exposure to the eyes, extremities, and deep tissue during percutaneous pedicle screw placement.
Summary of background data: Image-guided minimally invasive spinal surgery is typically performed with the use of fluoroscopy, exposing the surgeon and patient to ionizing radiation. The radiation dose to the surgeon has not been reported and risk to the surgeon performing this procedure over the long term is uncertain.
Methods: Percutaneous pedicle screws were placed in a cadaveric specimen from L2-S1 bilaterally using a cannulated pedicle screw system. Two fluoroscopes were used in the anteroposterior and lateral planes. The surgeon wore a thermolucent dosimeter ring on the right hand and badge over the left chest beneath the lead apron. Complete surgical time was recorded and a computed tomography scan was performed to assess screw placement. Radiation exposure was measured for total time of fluoroscopy use; average exposure per screw, surgical level, and dose to the eyes was calculated. This data was used to define the safety of percutaneous pedicle screw placement.
Results: Total fluoroscope time for placement of 10 percutaneous pedicle screws was 4 minutes 56 seconds (29 s per screw). The protected dosimeter recorded less than the reportable dose. The ring dosimeter recorded 103 mREM, or 10.3 mREM per screw placed. All screws were within the bone confines with acceptable trajectory. Exposure to the eyes was 2.35 mREM per screw.
Conclusions: On the basis of this data, percutaneous pedicle screw placement seems to be safe. A surgeon would exceed occupational exposure limit for the eyes and extremities by placing 4854 and 6396 screws percutaneously, respectively. Lead protected against radiation exposure during screw placement. The "hands-off" technique used in this study is recommended to minimize radiation exposure. Lead aprons, thyroid shields, and leaded glasses are recommended for this procedure.