Fig. 2From: The application of the acoustic shadowing facilitates guidance in radial artery puncture and cannulation teaching in standardized training for residents: a randomized controlled trialSchematic diagram of the acoustic shadowing of the double developing line. D1 (purple line) represents the transverse diameter of the radial artery; D2 (yellow line) represents the longitudinal diameter of radial artery; D3 (green line) represents the depth from skin to radial artery centerBack to article page