IEEE Trans Biomed Eng. 2023 Feb;70(2):553-564. doi: 10.1109/TBME.2022.3197213. Epub 2023 Jan 19.
Interstitial and intracavitary ultra- sound applicators had been developed and studied for minimally invasive treatments (MIT). However, the acoustic outputs are limited by the small-size PZT. We therefore studied the acoustic waveguide (AW) applicator which enables the use of a large-size PZT, and we aimed to advance AW applicators towards thermal ablation applications.
Double parabolic reflectors wave-guided ultrasonic transducer (DPLUS) was introduced which has two parabolic reflectors for enhancing the acoustic output. Theoretical modeling was conducted for optimizing the DPLUS thin waveguide.
Modeling results showed that optimal a/Λ (thin waveguide radius/wavelength) can be found and the optimal a depends on the excitable vibration amplitude in the thin waveguide. A local optimal a/Λ= 0.2392 was considered the best choice, which results in the optimal frequency of 2.2 MHz at the radius a of 0.6 mm. To verify this optimal frequency, experiments under two working frequencies of 1.0282 MHz and 2.2579 MHz were conducted. Temperature rise curves in the chicken breast tissue showed good agreements between experiments and modeling results, which proved the effectiveness of the modeling. In addition, experiments showed an ablated area with a diameter of 1.03±0.12 mm under continuous excitation of 2.2579 MHz and 5 s.
The developed DPLUS advanced the AW applicators towards thermal ablation applications.
This study provides the evidence for recognizing AW applicators as a technique for thermal ablation.
为了实现微创治疗（MIT），已经开发并研究了用于间质和腔内的超声治疗设备。然而，声输出受到小尺寸 PZT 的限制。因此，我们研究了声导波（AW）治疗设备，该设备可以使用大尺寸 PZT，并旨在将 AW 治疗设备推进到热消融应用。
介绍了双抛物面反射器波导超声换能器（DPLUS），它有两个抛物面反射器用于增强声输出。进行了理论建模以优化 DPLUS 薄波导。
建模结果表明，可以找到最佳的 a/Λ（薄波导半径/波长），并且最佳的 a 取决于薄波导中的可激励振动幅度。局部最佳的 a/Λ=0.2392 被认为是最佳选择，其最佳频率为 2.2MHz，在半径 a 为 0.6mm 时。为了验证这个最佳频率，在 1.0282MHz 和 2.2579MHz 的两个工作频率下进行了实验。鸡胸脯组织中的温升曲线表明实验与建模结果之间具有良好的一致性，这证明了建模的有效性。此外，实验在 2.2579MHz 连续激励下，5s 时得到直径为 1.03±0.12mm 的消融区域。
所开发的 DPLUS 推动了 AW 治疗设备向热消融应用的发展。
本研究为将 AW 治疗设备作为热消融技术提供了依据。
