Operator radiation doses during CT-guided spine procedures

Objectives: To perform a pilot study to quantify the radiation dose incident on operators during CT-guided interventional spine procedures, and provide a quick method to approximate it based on the total amount of radiation reported by the CT scanner. Patients and Methods: Data retrospectively obtained from 26 consecutive CT-guided spine procedures, encompassing a variety of interventions. Intermittent low-dose limited-coverage CT-scanning performed using a "step and shoot" mode to visualize needle advancement. The operator wore an electronic direct dosimeter to record the dose measured above the operator's lead apron [mu Gy] for each procedure. Total amount of radiation used for CT-guidance quantified by the Dose-Length Product (DLP) [mGy-cm] provided by the CT scanner. The relationship between the operator's dose and the DLP was assessed. Results: Average and median operator's dose were 2.3 and 1.9 mu Gy, respectively, with half of these values ranging between 0.7 and 2.5 mu Gy. Average and median DLP values used to perform the CT-guided procedure were 58 and 54 mGy-cm respectively, and half of these values ranged between 38 and 68 mGy-cm. There was a statistically significant correlation between the operator's dose and the DLP used to perform CT-guidance (r = 0.61), with an operator's dose-DLP conversion factor of 0.04 mu Gy / 1 mGy-cm (range: 0.006-0.083 mu Gy / 1 mGy-cm). Conclusions: In our series, the average amount of radiation used during CT guided procedures was about 50 mGy-cm (DLP), and the corresponding average operator's dose was about 2 mu Gy. We showed how an approximate estimate of the operator's dose could be obtained right after each procedure, based on the CT-scanner DLP output.