Liu Jingfei, Foiret Josquin, Stephens Douglas N, Le Baron Olivier, Ferrara Katherine W
Department of Biomedical Engineering, University of California, Davis, CA 95616-8686, USA.
Phys Med Biol. 2016 Jul 21;61(14):5275-96. doi: 10.1088/0031-9155/61/14/5275. Epub 2016 Jun 29.
A 1.5 MHz prolate spheroidal therapeutic array with 128 circular elements was designed to accommodate standard imaging arrays for ultrasonic image-guided hyperthermia. The implementation of this dual-array system integrates real-time therapeutic and imaging functions with a single ultrasound system (Vantage 256, Verasonics). To facilitate applications involving small animal imaging and therapy the array was designed to have a beam depth of field smaller than 3.5 mm and to electronically steer over distances greater than 1 cm in both the axial and lateral directions. In order to achieve the required f number of 0.69, 1-3 piezocomposite modules were mated within the transducer housing. The performance of the prototype array was experimentally evaluated with excellent agreement with numerical simulation. A focal volume (2.70 mm (axial) × 0.65 mm (transverse) × 0.35 mm (transverse)) defined by the -6 dB focal intensity was obtained to address the dimensions needed for small animal therapy. An electronic beam steering range defined by the -3 dB focal peak intensity (17 mm (axial) × 14 mm (transverse) × 12 mm (transverse)) and -8 dB lateral grating lobes (24 mm (axial) × 18 mm (transverse) × 16 mm (transverse)) was achieved. The combined testing of imaging and therapeutic functions confirmed well-controlled local heating generation and imaging in a tissue mimicking phantom. This dual-array implementation offers a practical means to achieve hyperthermia and ablation in small animal models and can be incorporated within protocols for ultrasound-mediated drug delivery.
设计了一种具有128个圆形元件的1.5兆赫兹长椭球形治疗阵列，以适配用于超声图像引导热疗的标准成像阵列。这种双阵列系统的实现将实时治疗和成像功能集成到一个超声系统（Vantage 256，Verasonics）中。为便于涉及小动物成像和治疗的应用，该阵列被设计成具有小于3.5毫米的波束景深，并能在轴向和横向方向上超过1厘米的距离进行电子扫描。为了达到所需的f数0.69，在换能器外壳内匹配了1 - 3个压电复合模块。通过实验评估了原型阵列的性能，与数值模拟结果吻合良好。获得了由 -6分贝聚焦强度定义的焦体积（轴向2.70毫米×横向0.65毫米×横向0.35毫米），以满足小动物治疗所需的尺寸。实现了由 -3分贝聚焦峰值强度定义的电子波束扫描范围（轴向17毫米×横向14毫米×横向12毫米）和 -8分贝横向栅瓣（轴向24毫米×横向18毫米×横向16毫米）。成像和治疗功能的联合测试证实了在组织模拟体模中能良好控制局部发热的产生和成像。这种双阵列实现方式为在小动物模型中实现热疗和消融提供了一种实用手段，并且可以纳入超声介导药物递送的方案中。
