Dalecki D, Child S Z, Raeman C H, Cox C, Carstensen E L
Department of Electrical Engineering, University of Rochester 14627, USA.
Ultrasound Med Biol. 1997;23(5):777-81. doi: 10.1016/s0301-5629(97)00070-7.
Ten-day old swine were used in the final step of a study of the age dependence of the threshold for lung hemorrhage resulting from exposure to diagnostically relevant levels of pulsed ultrasound. A 2.3-MHz focused transducer (pulse length of 10 microseconds, 100-Hz pulse repetition frequency) was incremented vertically at several sites for a distance of 2 or 2.5 cm over the chest of the subject for a total exposure period of 16 or 20 min. The procedure was repeated at a total of four sites per animal. Animals were euthanized and lungs were scored by visual inspection for numbers and areas of gross hemorrhages. The threshold level for hemorrhage was approximately 1.3-MPa peak positive pressure in water and the surface of the animal or, at the surface of the lung, 0.8-MPa peak positive pressure, 0.8-MPa fundamental pressure, 0.7-MPa maximum negative pressure and 20 Wcm-2 pulse average intensity. These values are essentially the same as those reported previously for neonatal swine, and neonatal, juvenile and adult mice.
在一项关于暴露于诊断相关水平的脉冲超声下导致肺出血阈值的年龄依赖性研究的最后阶段，使用了10日龄的猪。一个2.3兆赫兹的聚焦换能器（脉冲长度为10微秒，脉冲重复频率为100赫兹）在受试者胸部的几个部位垂直递增移动2或2.5厘米的距离，总暴露时间为16或20分钟。每只动物总共在四个部位重复该操作。对动物实施安乐死后，通过肉眼检查对肺部的大出血数量和面积进行评分。出血的阈值水平在水中以及动物体表约为1.3兆帕的峰值正压，在肺表面为0.8兆帕的峰值正压、0.8兆帕的基波压力、0.7兆帕的最大负压和20瓦/平方厘米的脉冲平均强度。这些值与先前报道的新生猪以及新生、幼年和成年小鼠的值基本相同。
