Department of Electrical Engineering, Chang-Gung University, Molecular Imaging Center Chang-Gung Memorial Hospital, Taoyuan, Taiwan.
Med Phys. 2007 Jul;34(7):2957-67. doi: 10.1118/1.2746508.
Focus splitting using sector-based phased arrays increases the necrosed volume in a single sonication and reduces the total treatment time in the treatment of large tumors. However, split-focus sonication results in a lower energy density and worse focal-beam distortion, which limits its usefulness in practical treatments. Here, we propose a new heating strategy involving consecutive strongly focused and split-focus sonications to improve the heating efficiency. Theoretical predictions including linear and thermal-dose-dependent attenuation change were employed to investigate potential factors of this strategy, and ex vivo tissue experiments were conducted to confirm its effectiveness. Results showed that the thermal lesions produced by the proposed strategy could be increased when comparing with the previous reported strategies. The proposed heating strategy also induces a thermal lesion more rapidly, and exhibits higher robustness to various blood perfusion conditions, higher robustness to various power/heating time combinations, and superiority to generate deep-seated lesions through tissues with complex interfaces. Possible mechanisms include the optimization of the thermal conduction created by the strongly focused sonication and the temperature buildup gained from thermally induced tissue attenuation change based on the theoretical analysis. This may represent a useful technique for increasing the applicability of split-focus and multiple-focus sonication techniques, and solve the obstacles encountered when attempting to use these methods to shorten the total clinical treatment time.
聚焦分裂使用基于扇区的相控阵在单次超声处理中增加了坏死体积，并减少了大肿瘤治疗的总治疗时间。然而，分焦超声处理导致能量密度降低和焦点波束失真更严重，限制了其在实际治疗中的应用。在这里，我们提出了一种新的加热策略，涉及连续的强聚焦和分焦超声处理，以提高加热效率。理论预测包括线性和热剂量依赖性衰减变化，用于研究该策略的潜在因素，并进行了离体组织实验以确认其有效性。结果表明，与以前报道的策略相比，所提出的策略产生的热损伤可以增加。所提出的加热策略还可以更快地产生热损伤，并且对各种血流灌注条件、各种功率/加热时间组合的更高稳健性以及通过具有复杂界面的组织生成深部病变的优越性。可能的机制包括通过理论分析优化由强聚焦超声产生的热传导和基于热诱导组织衰减变化获得的温度升高。这可能代表了一种增加分焦和多焦点超声处理技术适用性的有用技术，并解决了尝试使用这些方法缩短总临床治疗时间时遇到的障碍。
