Crystal Transducers for Harmonic Imaging

描述（申请人提供）：造影剂谐波成像已成为研究血液灌注的重要工具。由于恶性肿瘤周围有大量的血管生成，超声造影剂的使用有可能改善癌症的诊断和指导治疗。然而，由于缺乏足够的带宽，现有的换能器在从造影剂谐波形成图像的能力上受到限制。如果要使用二次谐波和次谐波来构建图像，则尤其如此。在第一阶段项目中，TRS技术公司、Blatek公司、J&W医疗有限责任公司和托马斯·杰斐逊大学医院通过使用单晶铁电构建一个非常宽带的换能器，展示了解决这个问题的方法。该材料（PbCMgi/sNb^CVPbTiOs - PMN-PT）具有非常高的机电耦合系数（kss > 90%），因此由其构建的超声波换能器具有固有的宽带宽。在I期项目中，单元件聚焦换能器由晶体/环氧树脂1-3复合材料构建。换能器的带宽为130%，在4.5 MHz发射频率的二次谐波和次谐波分别为9和2.25 MHz时具有良好的接收灵敏度。利用该传感器测量水中Sonazoid微泡产生的二次谐波信号强度，证明了造影剂检测的可行性。对于II期项目，TRS建议在这些结果的基础上构建宽带单晶线性阵列，并将其用于造影剂增强成像兔VX2肝肿瘤。

DESCRIPTION (provided by applicant): Contrast agent harmonic imaging has become a very important tool for studying blood perfusion. Due to the extensive amount of angiogenesis that occurs around malignant tumors, the use of ultrasound contrast agents has the potential to improve cancer diagnosis and to direct therapies. However, existing transducers are limited in their ability to form images from contrast agent harmonics because they lack sufficient bandwidth. This is especially true if both second and sub-harmonics are to be used to construct an image. In the Phase I program TRS Technologies, Blatek, Inc., J&W Medical, LLC, and Thomas Jefferson University Hospital demonstrated a solution to this problem by constructing a very broad band transducer using single crystal ferroelectric. This material (PbCMgi/sNb^CVPbTiOs - PMN-PT) has a very high electromechanical coupling coefficient (kss > 90%) so that ultrasound transducers constructed from it have an inherently broad bandwidth. In the Phase I program a single element, focused transducer was constructed from a crystal/epoxy 1-3 composite. The transducer had a bandwidth of 130% with excellent receive sensitivity at 9 and 2.25 MHz, the second and subharmonics, respectively, of the 4.5 MHz transmit frequency. Feasibility for contrast agent detection was demonstrated by using the transducer to measure the strength of 2nd harmonic signals generated by Sonazoid microbubbles in water. For the Phase II program, TRS proposes to build on these results by constructing a broad band single crystal linear array and using it for contrast agent enhanced imaging VX2 liver tumors in rabbits.