Abstract：
An 8 mm diameter, image-guided, annular array histotripsy transducer was fabricated and characterized. The array was laser etched on a 5 MHz, 1-3 dice and fill, PZT-5H/epoxy composite with a 45 % volume fraction. Flexible PCBs were used to electrically connect to the array elements using wirebonds. The array was backed with a low acoustic impedance epoxy mixture. A 3.6 by 3.8 mm, 64-element, 30 MHz phased array imaging probe was positioned in the center hole, to co-align the imaging plane with the bubble cloud produced by the therapy array. A custom 16-channel high voltage pulse generator was used to test the annular array for focal lengths ranging from 3- to 8-mm. An aluminum lens-focussed transducer with a 7 mm focal length was fabricated using the same piezocomposite and backing material and tested along with the histotripsy array. Simulated results from COMSOL FEM models were compared to measured results for low voltage characterization of the array and lens-focussed transducer. The measured transmit sensitivity of the array ranged from 0.113 to 0.167 MPa/V, while the lens-focussed transducer was 0.192 MPa/V. Simulated values were 0.160 to 0.174 MPa/V and 0.169 MPa/V, respectively. The measured acoustic fields showed a significantly increased depth-of-field compared the lens-focussed transducer, while the beamwidths of the array focus were comparable to the lens. The measured cavitation voltage in water was between 254 V and 498 V depending on the focal length, and 336 V for the lens-focussed transducer. The array had a lower cavitation voltage than the lens-focussed transducer for a comparable operating depth. The histotripsy array was tested in a tissue phantom and an in vivo rat brain. It was used to produce an elongated lesion in the brain by electronically steering the focal length from 3- to 8-mm axially. Real time ultrasound imaging with a Doppler overlay was used to target the tissue and monitor ablation progress, and histology confirmed the targeted tissue was fully homogenized.
摘要：
8毫米直径，图像引导，制造并表征环形阵列组织损伤换能器。阵列在5MHz上激光蚀刻，1-3骰子和填充，体积分数为45%的PZT-5H/环氧复合资料。柔性PCB用于使用引线键合电连接到阵列元件。该阵列用低声阻抗环氧树脂混合物作为背衬。3.6x3.8毫米，64元素，30MHz相控阵成像探头位于中心孔,将成像平面与治疗阵列产生的气泡云共同对准。使用定制的16通道高压脉冲发生器测试环形阵列的焦距范围为3至8-mm。使用相同的压电复合材料和背衬材料制造焦距为7mm的铝制透镜聚焦换能器，并与组织切片阵列一起进行测试。将COMSOLFEM模型的模拟结果与阵列和透镜聚焦换能器的低电压表征的测量结果进行比较。测量的阵列的发射灵敏度范围为0.113至0.167MPa/V，而透镜聚焦换能器为0.192MPa/V。模拟值为0.160至0.174MPa/V和0.169MPa/V，分别。与透镜聚焦换能器相比，测得的声场显示出明显增加的景深。而阵列焦点的波束宽度与透镜相当。在水中测得的空化电压在254V和498V之间，取决于焦距，和336V用于透镜聚焦换能器。对于可比的操作深度，该阵列的空化电压低于透镜聚焦的换能器。在组织体模和体内大鼠脑中测试组织切片阵列。通过以电子方式将焦距从3毫米轴向转向到8毫米，可以在大脑中产生细长的病变。使用多普勒叠加的实时超声成像来靶向组织并监测消融进展，和组织学证实目标组织完全匀浆化。
