Introduction
Pedicle screwing is widely utilized in spinal deformity correction surgery. Computed tomography (CT) navigated techniques were developed to improve the accuracy of pedicle screw placement and could be useful to avoid complication. However, potential cancer risks exist from associated ionizing radiation, in particular for children who are more radiosensitive than adults. The purpose of this study is to measure the radiation exposure dose directly to each organ and verify the reduction effect in scoliosis correction surgery.
Methods
Forty cases of adolescent idiopathic scoliosis had been performed correction and fusion surgery using CT navigated technique (O-arm, Medtronic). All patient was girl, and average age was 15.6 years old. Curve type was Lenke type 1 in all cases. Optically Stimulated Luminescence (OSL) dosimeters had been attached to eyelid, neck, breast, ovary, elbow and lower leg. Normal irradiation protocol (120 kVp, 32 mA) was adopted in first twenty cases, and the reduction protocol (120 kVp, 20 mA) was adopted in second twenty cases. All OSL dosimeter had been collected after the surgery, and radiation exposure doses for each organ were calculated. Average values were used for analysis.
Results
Average fusion vertebrae were 10.8, 11.1, respectively. Radiation exposure doses to eye were 388.4 µSv, 172 µSv, to thyroid were 2833 µSv, 1266 µSv, to breast were 15171 µSv, 8412 µSv, to ovary were 585 µSv, 512 µSv, to elbow were 199 µSv, 114 µSv, to lower leg 96 µSv, 33 µSv, respectively. There was statistically significance in radiation exposure to the eye, thyroid and breast. It stood comparison with the easiness in resolution between two groups.
Discussion
Spine surgeons should be aware of the potential risks as well as the benefits of CT and take these issues into account when using CT navigated technique for children. CT should be performed using every effort to use as low as reasonable dose of radiation while assuring acquisition of high-quality images. As there are few patients who are obese in children with scoliosis, it is thought that reduction protocol is available and useful in scoliosis correction surgery to reduce radiation exposure.