Damianou C, Hynynen K
Arizona Cancer Center, University of Arizona Health Sciences Center, Tucson 85724.
J Acoust Soc Am. 1994 Mar;95(3):1641-9. doi: 10.1121/1.408550.
The purpose of this study was to test the concept of using calculated thermal dose as a predictor for the necrosed tissue volume. A parametric study was conducted where the sonication parameters (pulse duration, power), transducer parameters (frequency, F number) and tissue properties (perfusion rate, attenuation) were varied and their effect on the lesion size was investigated. In vivo experiments where a focused ultrasound beam was used to induce tissue necrosis in thigh muscle of dog and rabbit were also conducted to obtain the reliability of the predictions. The experimental and simulated lesion sizes compared well. From the parametric study the threshold intensity for 1- and 5-s sonications were found to be about 1000 and 400 W/cm2, respectively. It was found that the lesion size was practically perfusion independent for pulses 5 s or shorter. The lesion size increases with increased pulse duration, acoustical power, and F number, but decreases with increased frequency provided that the focal intensity is kept constant. It was found also that the deeper the focus is in the tissue, the smaller the frequency range that causes selective tissue necrosis in the focal zone.
本研究的目的是验证使用计算热剂量作为坏死组织体积预测指标的概念。进行了一项参数研究，改变了超声参数（脉冲持续时间、功率）、换能器参数（频率、F数）和组织特性（灌注率、衰减），并研究了它们对损伤大小的影响。还进行了体内实验，使用聚焦超声束在狗和兔子的大腿肌肉中诱导组织坏死，以获得预测的可靠性。实验和模拟的损伤大小比较吻合。从参数研究中发现，1秒和5秒超声处理的阈值强度分别约为1000和400W/cm²。结果发现，对于5秒或更短的脉冲，损伤大小实际上与灌注无关。损伤大小随脉冲持续时间、声功率和F数的增加而增大，但在聚焦强度保持不变的情况下，随频率的增加而减小。还发现，焦点在组织中的深度越深，在焦点区域引起选择性组织坏死的频率范围越小。
