Study Design. An experimental model to assess radiation exposure during lum
bar pedicle screw insertion.
Objectives. To measure skin (patient) and scatter (surgeon) doses of radiat
ion during lumbar spine fluoroscopy to assess safety of the procedure for b
oth the surgeon and patient and determine best practice;
Summary of Background Data. Fluoroscopy assists with accuracy of pedicle sc
rew placement, yet the optimal technique of C-arm use and risk to both pati
ent and operating room staff from radiation exposure are unknown.
Methods. Entry- and scatter-dose recordings were made using a digital dosim
eter while screening an anthropomorphic phantom prone on a radiolucent oper
ating table. The source was positioned both superiorly and inferiorly with
the height varied in the latter orientation to create a working space under
the C-arm. The senior author's fluoroscopy records were reviewed in 140 co
nsecutive cases.
Results. In a series of 140 patients who underwent pedicle screw fixation,
the fluoroscopy time was 1.4 minutes per case or 0.33 minutes per screw. In
the source-superior position, the effective dose received by the patient w
as approximately 2.3 mSv per case. In the source-inferior position with a w
orking space of 300 mm, the effective dose was 6.8 mSv. Scatter dose to the
surgeon was higher in the source-superior position but was still less than
10% of recommended limits for the hand, thyroid, and eyes.
Conclusions. The source-superior position is the preferred position for ped
icle screw screening if a working space is required. Patient exposure is mi
nimized, and surgeon dose is well within current recommendations.