Experimental Study to Bend Thin Catheter Independent to Ultrasound Propagation Direction by Tempo-Spatial Division Emission Using Multiple Transducers

We have already experimented on the bending of a thin catheter with acoustic radiation force not only in the direction of ultrasound propagation but also in the direction perpendicular to ultrasound propagation using a single 2D array transducer, which produced a focal point and steered it simultaneously by changing the delay time of sound elements. Considering various clinical situations, developing the method of bending the catheter in any direction is mandatory. Therefore, we introduced two identical 2D array transducers with 128 elements each to bend the catheter in the direction independent to ultrasound propagation by establishing tempo-spatial division emission and their combination. As the result, the catheter was placed in the direction perpendicular to the acoustic propagation, and bent in the direction perpendicular to both the catheter and the acoustic propagation. We prepared totally four emission patterns, which determine the repetition time of burst wave and the delay time between two transducers to compare the behavior of the tip of the catheter. Then we derived the appropriate condition with the transition rate of the focal point of 2.0 mm/s, and the spatial interval of 1.0 mm considering the initial offset, which is an important parameter related to detection accuracy of the initial position of the thin catheter considering the future in vivo application.