BIOEFFECTS OF GAS BODY ACTIVATION IN MEDICAL ULTRASOUND

医用超声的安全性考虑必然涉及 空化的非热机制。如果气体体最初是 存在于生物介质中，然后是特殊类型的超声波 空化称为气体激活(GBA)，可以是生物空化- LY在相对较低的暴露水平下有效。在更高级别，GBA 进展为更剧烈的空化现象，并伴随着自由 自由基的产生和声化学效应。在哺乳动物中，GBA预计 是一种微妙的现象，虽然不常见，但具有潜在的重大意义 后果。气体活化的物理研究已在 疏水性植物、昆虫和充气微孔的研究 膜。这项研究将通过评估新类型的气体来继续 蓝藻中含有气泡的物体，超声造影剂 药剂，以及自然空化成核气体，显然 存在于体外和体内。对这一关系的理论探讨 在非热机制之间，如声流和自由 自由基，以及由此产生的潜在生物效应将提供一般 超越特定条件的预测效用洞察力 实验。使用体外模型系统，如充气 微孔，将继续评估微孔的破坏能力 流动剪应力和空化的声化学产物 在培养的细胞中。最后，生物物理研究将在#年启动。 用于测量GBA生物效应的哺乳动物模型系统 与医学相关的疾病。这些跨学科的研究是 认真整合并重点阐明全球环境管理局的作用 以及超声医学生物物理学中的空化现象。因为奥委会- 哺乳动物中空化的电流、作用和影响几乎仍然存在 关于GBA潜在生物效应的未知基本信息是紧迫的- LY是风险评估工作所需要的。对生物效应的认识 气体活化将有助于可能的假说发展 未来的哺乳动物和流行病学研究，并将有助于形成一个 临床情况下的剂量学基础和照射标准。

Safety consideration of medical ultrasound necessarily involves the nonthermal mechanism of cavitation. If bodies of gas are initially present in a biological medium, then the special type of ultrasonic cavitation called gas body activation (GBA) occurs and can be biological- ly effective at relatively low levels of exposure. At higher levels, GBA progresses into more violent cavitation phenomenon with associated free radical generation and sonochemical effects. In mammals, GBA is expected to be a subtle phenomenon with infrequent, but potentially significant consequences. The physics of gas body activation has been studied in research on plants, insects and gas-filled micropores in hydrophobic membranes. This research will be continued by assessing new types of gas bodies including gas vesicles in blue-green algae, ultrasonic contrast agents, and the natural cavitation-nucleating gas bodies which apparently exist in vitro and in vivo. Theoretical investigation of the relation between nonthermal mechanisms, such as acoustic streaming and free radicals, and the resulting potential for bioeffects will provide general insights with predictive utility beyond the specific conditions of the experiments. Use of in vitro model systems, such as the gas-filled micropore, will be continued to assess the damaging ability of micro- streaming shear stresses and of the sonochemical products of cavitation in cultured cells. Finally, biophysical studies will be initiated in mammalian model systems for the measurement of GBA bioeffects under medically-relevant conditions. These interdisciplinary studies are carefully integrated and focussed on the elucidation of the role of GBA and cavitation in the medical biophysics of ultrasound. Since the oc- currence, action and effects of cavitation in mammals remain virtually unknown, basic information on the potential for GBA bioeffects is urgent- ly needed for risk assessment efforts. Knowledge of the bioeffects of gas body activation will aid in hypothesis development for possible future mammalian and epidemiological studies, and will help to form a basis for dosimetry and exposure criteria in the clinical situation.