Radiation Reduction Ultrasound during PNL Ultrasound + Fluoroscopy Fluoroscopy p Value Basiri A, et al. 41.4 s 57.0 s 28.6 s p=0.0001 Agarwal M, et al. 14.4 s p<0.01 Basiri A, et al. J Endourol 2008 Agarwal M, et al. BJU Int 2011