BIOEFFECTS OF GAS BODY ACTIVATION IN MEDICAL ULTRASOUND

描述：(改编自调查人员摘要) 医学超声需要对安全问题进行持续评估。 目前人们关注的焦点是气体的非热生物效应机制。 身体激活(GBA)和惯性空化，特别是与 气体造影剂在诊断超声中的应用 程序。如果最初存在合适的气体，就会发生GBA。 有可能造成细胞膜的损伤。在更高的幅度下， 惯性空化可能会引发细胞DNA损伤。 在哺乳动物中，这些现象可能是微妙的或极具破坏性的： 它既有潜在的副作用，也有治疗作用。 利益。本研究有四个具体目的：(1)敏感的非 计划了旋转曝光系统，可以带来微尺度的 细胞和气泡之间的相互作用，揭示了 剂量学关系。(2)气体造影剂注射 对其他无风险暴露的空化生物效应的可能性 条件。实验的目的将是描述 这些药物处于低水平，并正在确定它们是否可以导致 医学相关条件下的惯性空化。此外, 将重点检查这些制剂的生物效应能力。 用于治疗目的的特定靶向癌细胞的研究。(3)DNA 细胞直接暴露于惯性空化引起的链断裂 最近由小说《彗星》分析揭示。其作用机制 并将检查这种DNA损伤的遗传后果，其 如果与医学超声波有任何关系，将予以确定。(4) 肠道出血可由超声波加热或由 空化单独作用。这一点可能的协同增强 当两种机制都运行时，将研究其效果。最后，组织 气体造影剂空化或活化引起的损伤 在其他器官，如肾脏，将被调查和定义。 这项研究产生的定量剂量学信息是 迫切需要对超声技师进行风险评估和指导，以及 以充分发挥医用超声波的治疗潜力。

DESCRIPTION: (Adapted from investigator's abstract) The evolution of medical ultrasonics requires continual evaluation of safety issues. Concern presently centers on the nonthermal bioeffects mechanisms of gas body activation (GBA) and inertial cavitation, particularly in relation to the use of gas-body contrast agents in diagnostic ultrasound procedures. If suitable gas bodies are present initially, GBA occurs with a possibility of cell membrane damage. At higher amplitudes, inertial cavitation may be initiated with a risk of cellular DNA damage. In mammals, these phenomena can be subtle or dramatically destructive: the potential exists for both harmful side effects and therapeutic benefit. This research has four specific aims: (1) Sensitive non- rotating exposure systems are planned, which can bring out micro-scale interactions between cells and bubbles and reveal the fundamental dosimetric relationships. (2) Gas-body contrast agents inject the potential for cavitational bioeffects into otherwise risk-free exposure conditions. Experiments will be aimed at characterizing the behavior of these agents at low levels and at determining if they can lead to inertial cavitation under medically-relevant conditions. In addition, the bioeffects capability of the agents will be examined with emphasis on specific targeting of cancer cells for therapeutic purposes. (3) DNA strand breaks induced by direct exposure of cells to inertial cavitation have recently been revealed by the novel "comet" assay. The mechanisms and genetic consequences of such DNA damage will be examined, and its relation, if any to medical ultrasonics will be determined. (4) Intestinal hemorrhage can be induced by either ultrasonic heating or by cavitation acting alone. The possible synergistic enhancement of this effect will be studied when both mechanisms operate. Finally, tissue damage related to cavitation or activation of gas-body contrast agents in other organs, such as the kidney, will be investigated and defined. The quantitative dosimetric information resulting from this research is urgently needed for risk assessment and guidance of sonographers, and for developing the full therapeutic potential of medical ultrasound.