50 patients scheduled for instrumented posterior thoracic or lumbar fusion surgery were randomized to intraoperative CT acquisition using either a low-dose protocol or high-dose protocol. Patients were assessed for correct pedicle screw placement using the Gertzbein and the Heary classifications, as well as radiation exposure using dosimeters. Rate of correct pedicle screw placement was significantly higher in the low-dose group compared to the high-dose group. Radiation exposure was also lower in the low-dose group at measured sites on either side of the surgical wound, and on the anterior and posterior sides of the patient.