IEEE Trans Biomed Eng. 2021 Oct;68(10):2930-2939. doi: 10.1109/TBME.2021.3056140. Epub 2021 Sep 20.
Traditional endoscopic ultrasonography (EUS), which uses one-dimensional (1-D) curvilinear or radial/circular transducers, cannot achieve dynamic elevational focusing, and the slice thickness is not sufficient. The purpose of this study was to design and fabricate a 1.5-dimensional (1.5-D) circular array transducer to achieve dynamic elevational focusing in EUS in vivo.
An 84 × 5 element 1.5-D circular array transducer was successfully developed and characterized in this study. It was fabricated with PZT-5H 1-3 composite that attained a high-electromechanical coupling factor and low-acoustic impedance. The acoustic field distribution was measured with different transmission modes to validate the 1.5-D elevational beam focusing capability. The imaging performance of the 84 × 5 element 1.5-D circular array transducer was evaluated by two wire phantoms, an agar-based cyst phantom, an ex vivo swine pancreas, and an in vivo rhesus macaque rectum based on multifocal ray-line imaging method with five-row elevational beam steering.
It was demonstrated that the transducer exhibited a central frequency of 6.47 MHz with an average bandwidth of 50%, a two-way insertion loss of 23 dB, and crosstalk of <-26 dB around the center frequency.
Dynamic elevational focusing and the enhancement of the slice thickness in EUS were obtained with a 1.5-D circular array transducer.
This study promotes the development of multirow and two-dimensional array EUS probes for a more precise clinical diagnosis and treatment.
传统的内镜超声（EUS）使用一维（1-D）曲线或径向/圆形换能器，无法实现动态高程聚焦，切片厚度不足。本研究旨在设计和制造一种 1.5 维（1.5-D）圆形阵列换能器，以实现体内 EUS 的动态高程聚焦。
本研究成功开发并表征了一个 84×5 元素的 1.5-D 圆形阵列换能器。它由 PZT-5H 1-3 复合材料制成，具有高机电耦合系数和低声阻抗。通过不同的传输模式测量声场分布，验证了 1.5-D 高程波束聚焦能力。使用多焦点射线线成像方法，通过两个线体幻影、基于琼脂的囊肿幻影、离体猪胰腺和体内恒河猴直肠对 84×5 元素 1.5-D 圆形阵列换能器的成像性能进行了评估，具有五排高程波束转向。
结果表明，该换能器在中心频率为 6.47MHz 时具有平均带宽为 50%的带宽，双向插入损耗为 23dB，在中心频率周围的串扰为<-26dB。
通过 1.5-D 圆形阵列换能器实现了 EUS 的动态高程聚焦和切片厚度的提高。
本研究促进了多排和二维阵列 EUS 探头的发展，以实现更精确的临床诊断和治疗。
