Fabrication of flow phantom to mimic blood vessel to adopt therapeutic experiment using ultrasound

We are developing a therapeutic system that uses acoustic radiation force to control a micro object in blood vessel aiming to reach target area such as tumors. However, there was limitation to perform verification experiments with in vivo blood vessels, because of the difficulties of inserting a micro object into an actual blood vessel. Therefore, we considered to fabricate a phantom with the actual shape of blood vessels which has a permeability of acoustic radiation force and a visualization on echogram as well as in vivo blood vessel. First, we prepared six types of materials including silicon and rubber to mimic vessel wall, which can be fabricated by a 3D printer. Next, we prepared agar to mimic surrounding tissues and blended graphite powder to reproduce speckles on echograms. After verification with echograms, the optimal combination selected was UV curable silicon rubber as vessel wall. The fabricated phantom with pseudo blood flow was examined for visualization of the branched structure by both B-mode and Doppler-mode. As the result of 3D reconstruction of the ultrasound volumes, the structure of the blood vessel was clearly visualized. Also, the phantom was applicable to an active induction experiment of thin catheter using acoustic radiation force.