Inserm, U556, Université de Lyon, Lyon, F-69003, France.
Phys Med Biol. 2011 Jun 21;56(12):3563-82. doi: 10.1088/0031-9155/56/12/008. Epub 2011 May 23.
A novel architecture for a phased-array high intensity focused ultrasound (HIFU) device was investigated, aiming to increase the capabilities of electronic steering without reducing the size of the elementary emitters. The principal medical application expected to benefit from these developments is the time-effective sonication of large tumours in moving organs. The underlying principle consists of dividing the full array of transducers into multiple sub-arrays of different resonance frequencies, with the reorientation of these individual emitters, such that each sub-array can focus within a given spatial zone. To enable magnetic resonance (MR) compatibility of the device and the number of output channels from the RF generator to be halved, a passive spectral multiplexing technique was used, consisting of parallel wiring of frequency-shifted paired piezoceramic emitters with intrinsic narrow-band response. Two families of 64 emitters (circular, 5 mm diameter) were mounted, with optimum efficiency at 0.96 and 1.03 MHz, respectively. Two different prototypes of the HIFU device were built and tested, each incorporating the same two families of emitters, but differing in the shape of the rapid prototyping plastic support that accommodated the transducers (spherical cap with radius of curvature/aperture of 130 mm/150 mm and, respectively, 80 mm/110 mm). Acoustic measurements, MR-acoustic radiation force imaging (ex vivo) and MR-thermometry (ex vivo and in vivo) were used for the characterization of the prototypes. Experimental results demonstrated an augmentation of the steering range by 80% along one preferentially chosen axis, compared to a classic spherical array of the same total number of elements. The electric power density provided to the piezoceramic transducers exceeded 50 W cm(-2) CW, without circulation of coolant water. Another important advantage of the current approach is the versatility of reshaping the array at low cost.
研究了一种用于相控阵高强度聚焦超声（HIFU）设备的新型架构，旨在提高电子转向能力，同时不减小基本发射器的尺寸。预计这些发展将主要受益于以下医学应用：在运动器官中对大型肿瘤进行高效超声处理。其基本原理是将完整的换能器阵列分为多个不同谐振频率的子阵列，并重新定向这些单独的发射器，使得每个子阵列都可以在给定的空间区域内聚焦。为了使设备具有磁共振（MR）兼容性，并将射频发生器的输出通道数量减半，使用了一种被动频谱复用技术，包括对具有固有窄带响应的频率偏移对压电陶瓷发射器进行并行布线。安装了两组 64 个发射器（圆形，直径 5 毫米），分别在 0.96 和 1.03 MHz 时效率最佳。构建并测试了两种不同的 HIFU 设备原型，每个原型都包含相同的两组发射器，但快速成型塑料支架的形状不同，该支架容纳了换能器（曲率半径/孔径为 130 毫米/150 毫米和 80 毫米/110 毫米的球形帽）。声学测量、MR-声辐射力成像（离体）和 MR-测温（离体和体内）用于原型的特性描述。实验结果表明，与相同总数元件的经典球形阵列相比，沿一个优选轴的转向范围增加了 80%。提供给压电陶瓷换能器的电功率密度超过 50 W cm(-2)CW，无需循环冷却水。当前方法的另一个重要优势是低成本重塑阵列的多功能性。
