Radiation Exposure during Pedicle Screw Placement in Adolescent Idiopathic Scoliosis: Is Fluoroscopy Safe?

Methods: Number of screws and fluoroscopy time were recorded. Thermoluminscent dosimeter (TLD)was used to determine radiation dosage. Group 1 consisted of 14 patients with TLD worn outside lead protection, and the 6 patient group 2 had TLD worn inside thyroid shield.

Results: Group 1: 322 screws were placed with exposure time of 2347 seconds (7.4/screw). This resulted in a TLD deep body dose of 152 mSv. Group 2: 122 screws were placed with a total of 629 seconds of exposure (5.2/screw). This resulted in deep body dose of 13 mSv. Calculations were done to estimate the annual radiation exposure to the surgeon, based 140 scoliosis surgeries. Group 1: the surgeon received 13.49 mSv radiation. Group 2: 4.31 mSv of radiation.

Discussion: The dosages in both trial are not negligible. The International Commision on Radiological Protection (ICRP) states that the maximum yearly dose limit for whole body exposure for classified workers (radiologist) is 20 mSv, and for the thyroid is 50 mSv. Non-classified workers (surgeons) are permitted only 30% of the classified worker level of radiation exposure. This single year reccommendation does not consider lifetime accumulated dosages. At the levels reported, a surgeon would surpass the recommended lifetime limits for non-classified workers after less than 10 years exposure. It is unlikely he would surpass the limits for classified workers, 86 years.

Conclusions: Serious questions regarding radiation safety during scoliosis surgery are raised. Long term risks of low level radiation are unknown. Acceptable levels of radiation are continually being revised downward.The surgeon employing fluoroscopy for pedicle screw placement should use maximum protection and be treated as a classified worker (radiologist), wearing a badge and having periodic examinations for radiation effects.

Hibbs Award Nominee for Best Clinical Paper