Fluoroscopy-guided vs. navigated iliosacral screw placement with intraoperative 3D scan or postoperative CT control: impact of the clinical workflow on radiation exposure

Objectives Different techniques are known to guide and verify safe placement of iliosacral screws (ISS). Fluoroscopy-guided (FSG) ISS placement or 3D navigation have provided similar results.

Intraoperative 3D scanning following guide wire placement allows a correction of malpositioned guide wires during the same procedure and may replace postoperative CT. Thus, revision surgery may be avoided. However, higher radiation exposure for the conventional technique is a concern. It was the aim of this experimental study to evaluate radiation exposure for three clinical workflows.

Methods An anthropomorphic, cross sectional dosimetry phantom, representing the body of a male human (173cm/73kg), was equipped with metal oxide semiconductor field effect transistors in various organ positions to measure organ specific radiation exposure. Each acquisition protocol was repeated three times to adjust the variability. The effective dose was calculated according to the guidelines of the International Commission on Radiological Protection. Radiation exposure was measured for FSG placement of 2 transverse ISS based on clinical experience regarding fluoroscopy time (lateral view 2 min; inlet and outlet views 1 min each). Additional measurements were conducted to calculate the effective dose for a 3D scan as used for navigated ISS (3D high-quality), for intraoperative verification of proper guide wire placement (3D standard-quality) and for postoperative CT, using a state-of-the-art scanner and protocol. The following workflows were compared: FSG including postoperative CT (FSG-CT) vs. FSG with intraoperative 3D scan (FSG-3D) vs. navigation (3D high-quality) including an intraoperative 3D standard-quality scan

(NAV-3D).

Results and Conclusion The effective dose for FSG-CT and FSG-3D were 5,12 mSv and 4.78 mSv, respectively. For NAV-3D, the effective dose was the lowest (3.00 mSv). The effective dose of a high-quality 3D scan required for navigation was 1.94 mSv, compared to 1.06 mSv for a standard-quality 3D scan. Radiation exposure of a standard-quality 3D scan was comparable to postoperative CT (1.06 vs. 1,40 mSv) with both counting for <  40% compared to the effective dose for FSG ISS placement (3.72 mSv).

Intraoperative 3D scanning can be recommended, either combined with prior FSG ISS placement or following 3D navigation without increasing radiation exposure compared with alternative workflows with postoperative CT control.

Stichwörter iliosacral screws, navigation, fluoroscopy guided, radiation exposure

Publication History

Article published online:
15 October 2020