Basic Properties of Ultrasonic Probe with a Through Hole for Medical Application

In the medical field, an easy-to-operate small ultrasonic probe is required to insert a needle precisely into a puncture target such as vessels or a lesion area. We fabricated an ultrasonic probe with a through hole for needle puncture during observation of a puncture target. The probe consists of a ring-shaped transducer around the hole for detecting the needle tip and 12 fan-shaped transducers around the ring-shaped transducer for observing a puncture target. We obtained a B-mode image of a needle puncturing a pig liver using this probe. To discuss the principle of detecting a needle tip, we investigated the phase of signals from the needle tip using an ultrasonic probe on which the transmitter and receiver were separated. From the experimental results, we explain the principle of detection.