Fig. 1From: The application of the acoustic shadowing facilitates guidance in radial artery puncture and cannulation teaching in standardized training for residents: a randomized controlled trialThe double developing lines were tied on the ultrasound probe perpendicular to the long axis. A Design of ultrasound probe for double developing lines. B Ultrasonic image of the radial artery (arrow) and the acoustic shadowing of the double developing line (arrowheads)Back to article page