THE ROLE OF NONLINEAR ULTRASOUND PROPAGATION DURING HYPERTHERMIA TREATMENTS
THE ROLE OF NONLINEAR ULTRASOUND PROPAGATION DURING HYPERTHERMIA TREATMENTS
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DOI：
10.1118/1.596626
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发表时间：
1991-11-01
期刊：
影响因子：
3.8
通讯作者：
HYNYNEN, K
中科院分区：
文献类型：
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作者：
HYNYNEN, K
在本研究中，研究了在恶性肿瘤的超声热疗过程中利用非线性超声传播来控制功率沉积模式的可行性。 从体内结果来看，通过增加源的时间峰值功率同时降低占空比以保持相同的声学时间平均功率，可以显着改变功率沉积模式和温度分布。 热疗超声处理期间获得的最大温度增益（1.5 至 2 之间）明显小于通过改变换能器的频率和其他参数获得的温度增益，因此，在设计热疗系统和计划治疗时应使用超声场的线性特性。 然后，在处理过程中，非线性传播可用于提供功率沉积图案的在线控制。 换能器特性决定了温度增益的大小，并且当在 0.25 至 1.68 MHz 之间的频率使用锐聚焦（F 数 = 1）换能器时，由于超过瞬态空化阈值的高压幅度，无法达到非线性传播区域。
In this study the feasibility of utilizing nonlinear ultrasound propagation to control the power deposition patterns during ultrasound hyperthermia treatments of malignant tumors was investigated. From the in vivo results it appears that the power deposition pattern and the temperature distributions can be significantly altered by increasing the temporal peak power of the source while reducing the duty cycle to maintain the same acoustic time average power. The maximum temperature gains obtained during hyperthermia sonication (between 1.5 and 2) were significantly less than one could obtain by varying the frequency and the other parameters of transducers and thus, the linear characteristics of the ultrasound fields should be used when hyperthermia systems are designed and treatments are planned. Then during the treatment nonlinear propagation can be used to provide on-line control of the power deposition patterns. The transducer characteristics determined the magnitude of the temperature gain and the nonlinear propagation region could not be reached when sharply focused (F number = 1) transducers were used at the frequencies between 0.25 to 1.68 MHz due to the high pressure amplitudes that exceeded the transient cavitation threshold.