BIOEFFECTS OF GAS BODY ACTIVATION IN MEDICAL ULTRASOUND

医疗实践涉及一个重要的和日益增长的应用， 超声能量既用于诊断目的，这不应该引起 生物效应，并用于治疗目的，这应该有效地诱导 期望的效果。 超声波引起哺乳动物组织的生物变化 主要通过加热，但也可以通过超声波产生生物效应 气穴现象 由于空化的不确定性， 关于适当剂量测定参数、暴露的明确信息 关于使用超声的标准或指南， 替代模式。 如果气体最初存在于 生物介质中，然后一个微妙的形式空化所谓的气体机构 激活可发生在所有暴露水平， 与医疗诊断方法相关的水平。 我们提出一个彻底的， 气体体激活物理学的基础研究，及其病因学 生物效应 具体目标是：1）研究红细胞释放ATP 暴露于超声活化的充气微孔， 各种物理和生物物理参数，2）分析这些 实验数据通过应用物理理论为 振荡的气体机构和非热机制， 作用于微孔附近的细胞，3）考虑微孔的存在和行为 新形式的气体体，如稳定的微泡， 超声造影剂在超声心动图，和4）调查 可能的sublytic效应的气体机构，如 对吞噬细胞的功能、形态和表面影响。 我们 假设检验方法导致洞察力的预测价值超越 特定实验的限制条件。 这样的结果减少了 空化生物效应的不确定性，以及 气体体激活在医学物理学中的作用的阐明 超声.

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.