BIOEFFECTS OF GAS BODY ACTIVATION IN MEDICAL ULTRASOUND

医疗实践涉及到大量且不断增长的应用 超声能量既用于诊断目的，不应引起 生物效应，以及治疗目的，这应该有效地诱导 期望的效果。超声波在哺乳动物组织中引起生物变化 主要通过加热，但也可以通过超声波产生生物效果 空化。由于空化的不确定性，缺乏 关于适当剂量学参数、照射的明确信息 与使用超声波有关的标准或指南 另一种模式。如果气体体最初存在于 生物介质，然后是一种微妙的空化形式，称为气体 激活可以发生在所有级别的暴露中，并产生效果，即使在 与医学诊断方法相关的水平。我们建议一项彻底的， 气体活化物理及其成因的基础研究 生物效应。具体目标是：1)研究红细胞三磷酸腺苷的释放 暴露在超声激活的充气微孔中，作为 各种物理和生物物理参数，2)分析这些 通过应用物理理论获得的实验数据 微孔气体的振动性及其非热机制 作用于微孔附近的细胞，3)考虑其存在和行为 新形式的气体，例如用作 超声心动图中的超声造影剂；4)探讨超声造影剂在超声心动图中的应用 微孔气体次溶蚀作用的可能性，如 吞噬细胞的功能、形态和表面效应。我们的 假设检验方法带来具有预测价值之外的洞察力 具体实验的有限条件。这样的结果降低了 关于空化生物效应的不确定性，以及朝着 阐明气体激活在医用物理中的作用 超音波。

Medical practice involves a significant and growing application of ultrasonic energy both for diagnostic purposes, which should not incur bioeffects, and for therapeutic purposes, which should efficaciously induce desired effects. Ultrasound causes biological change in mammalian tissue primarily through heating, but can also produce bioeffects via ultrasonic cavitation. Due to uncertainties about cavitation, there is a lack of definitive information on appropriate dosimetric parameters, exposure criteria or guidance with regard to the use of ultrasound relative to alternative modalities. If bodies of gas are initially present in a biological medium, then a subtle form of cavitation called gas body activation can occur at all levels of exposure and produce effects even at levels relevant to medical diagnostic methods. We propose a thorough, basic study of the physics of gas body activation, and the etiology of its bioeffects. Specific aims are: 1) to study ATP release from erythrocytes exposed to ultrasonically activated gas-filled micropores as a function of various physical and biophysical parameters, 2) to analyze these experimental data through application of physical theory for the oscillation of the micropore gas bodies and for nonthermal mechanisms which act on cells near the micropores, 3) to consider the existence and behavior of new forms of gas bodies, such as the stabilized microbubbles employed as ultrasonic contrast agents in echocardiography, and 4) to investigate the possibility of sublytic effects of the micropore gas bodies, such as functional, morphological and surface effects on phagocytic cells. Our hypothesis-testing approach leads to insights with predictive value beyond the limited conditions of specific experiments. Such results reduce the uncertainties about cavitation bioeffects, and progress toward the elucidation of the role of gas body activation in the medical physics of ultrasound.