Digby M, Duck F A, Lenz E J, Price G J
Medical Physics Department, Royal United Hospital, Bath, UK.
Br J Radiol. 1995 Nov;68(815):1244-8. doi: 10.1259/0007-1285-68-815-1244.
This note describes a method for the measurement of hydroxyl free radical concentration due to collapse acoustic cavitation in medical ultrasound fields using aqueous terephthalic acid (TA) solution. An enclosed cylindrical chamber with acoustically transparent membranes at either end was used. Control of cavitation activity was achieved by seeding the solution with polystyrene microspheres to provide cavitation centres. Insonation experiments using unseeded TA previously exposed to air gave very variable results, sometimes detecting cavitation activity and at other times detecting nothing, under the same exposure conditions. Introduction of polystyrene microsphere seeds into the TA enabled it to detect reproducibly levels of cavitation activity at least one order of magnitude higher than in unseeded solutions. An experiment using the seeded TA in a standing wave ultrasound field, set up using a brass reflecting plate, demonstrated that the presence of a standing wave inhibited the measured cavitation yield.
本笔记描述了一种使用对苯二甲酸（TA）水溶液测量医学超声场中由于空化声塌陷产生的羟基自由基浓度的方法。使用了一个两端带有声学透明膜的封闭圆柱形腔室。通过向溶液中加入聚苯乙烯微球以提供空化中心来实现对空化活性的控制。在相同的暴露条件下，对先前暴露于空气中的未加微球的TA进行超声照射实验，结果变化很大，有时能检测到空化活性，有时则什么也检测不到。将聚苯乙烯微球种子引入TA中后，它能够以可重复的方式检测到比未加微球的溶液中空化活性水平至少高一个数量级的情况。在使用黄铜反射板设置的驻波超声场中对加了微球的TA进行的一项实验表明，驻波的存在抑制了所测量的空化产率。
