Measures of patient radiation exposure during endoscopic retrograde cholangiography: beyond fluoroscopy time

To determine whether fluoroscope time is a good predictor of patient radiation exposure during endoscopic retrograde cholangiopancreatography.

This is a prospective observational study of consecutive patients undergoing endoscopic retrograde cholangiopancreatography in a tertiary care setting. Data related to radiation exposure were collected. The following measures were obtained: Fluoroscopy time (FT), dose area product (DAP) and dose at reference point (DOSERP). Coefficients of determination were calculated to analyze the correlation between FT, DAP and DOSRP. Agreement between FT and DAP/DOSRP was assessed using Bland Altman plots.

Four hundred sixty-three data sets were obtained. Fluoroscopy time average was 7.3 min. Fluoroscopy related radiation accounted for 86% of the total DAP while acquisition films related radiation accounted for 14% of the DAP. For any given FT there are wide ranges of DAP and DOSERP and the variability in both increases as fluoroscopy time increases. The coefficient of determination (R(2)) on the non transformed data for DAP and DOSERP versus FT were respectively 0.416 and 0.554. While fluoroscopy use was the largest contributor to patient radiation exposure during endoscopic retrograde cholangiography (ERCP), there is a wide variability in DAP and DOSERP that is not accounted for by FT. DAP and DOSERP increase in variability as FT increases. This translates into poor accuracy of FT in predicting DAP and DOSERP at higher radiation doses.

DAP and DOSERP in addition to FT should be adopted as new ERCP quality measures to estimate patient radiation exposure.