Editor's Choice - Estimated Radiation Dose to the Operator During Endovascular Aneurysm Repair

To estimate operator organ doses from fluoroscopically guided infrarenal endovascular aneurysm repair (EVAR) procedures, using the detailed exposure information contained in radiation dose structured reports.

Conversion factors relating kerma area product (P_KA) to primary operator organ doses were calculated using Monte Carlo methods for 91 beam angles and seven x-ray spectra typical of clinical practice. A computer program was written, which selects the appropriate conversion factor for each exposure listed in a structured report and multiplies it by the respective P_KA. This system was used to estimate operator doses for 81 EVAR procedures for which structured reports were available. The impact of different shielding scenarios and variations in operator position was also investigated.

Without any shielding, the median estimated effective dose was 113 microSv (interquartile range [IQR] 71, 252 microSv). The highest median organ doses were for the colon (154 microSv, IQR 81, 343) and stomach (133 microSv, IQR 76, 307). These dose estimates represent all exposures, including fluoroscopy and non-fluoroscopic digital acquisitions. With minimal shielding provided by 0.25 mm of Pb covering the torso and upper legs, the effective dose was reduced by a factor of around 6. With additional shielding from ceiling and table shields, a 25 to 50 fold reduction in dose is achievable. Estimated doses were highest where the primary beam was pointed directly away from the operator.

The models suggest that with optimal use of shielding, operator doses can be reduced to levels equivalent to one to two days of natural background exposure and well below statutory dose limits.