Mean effective dose for sham vs. radiation-attenuating drape was 0.210.27 vs. 0.020.02 mSv at the endoscopist 's eye , 0.350.44 vs. 0.030.03 mSv at the endoscopist 's neck , and 0.270.34 vs. 0.020.02 mSv at the nurse 's neck ( P < 0.0001 for all comparisons ) .