Object: Minimally invasive transforaminal lumbar interbody fusion (TLIF) is an increasingly popular procedure. The technique involves use of fluoroscopy to assist with pedicle screw (PS) placement. The potential exists for both the surgeon and the patient to become exposed to significant amounts of radiation. The authors undertook this study to quantify the radiation dose to the surgeon and patient during minimally invasive TLIF.
Methods: The authors undertook a prospective study of 24 consecutive patients who underwent minimally invasive TLIF. All surgeries were performed by the senior author (R.K.B.), who used techniques previously described. The surgeon wore a radiation monitor under an apron-style lead shield at waist level, at an unshielded collar location, and as a sterile ring badge containing a thermoluminescent dosimeter on the dominant (right) hand ring finger. Dosimeter readings were obtained for each case. A total of 33 spinal levels were treated in 24 patients. All treated levels were between L3-4 and L5-S1. In all cases of 1-level disease, 4 PSs were placed, and in all cases of 2-level disease, 6 screws were placed.
Results: Mean fluoroscopy time was 1.69 minutes per case (range 3.73-0.82 minutes). Mean exposure per case to the surgeon on his dominant hand was 76 mRem, at the waist under a lead apron was 27 mRem, and at an unprotected thyroid level was 32 mRem. Mean exposure to the patient's skin was 59.5 mGy (range 8.3-252 mGy) in the posteroanterior plane and 78.8 mGy (range 6.3-269.5 mGy) in the lateral plane.
Conclusions: To the authors' knowledge, this is the first study of radiation exposure to the surgeon or patient in minimally invasive TLIF. Patient exposures were low and compare favorably with exposures involving other common interventional fluoroscopically guided procedures. Surgeon exposures are limited but require careful monitoring. Annual dose limits could be exceeded if a large number of these and other fluoroscopically guided procedures were performed.