Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels
Infrared mapping of ultrasound fields generated by medical transducers: Feasibility of determining absolute intensity levels
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DOI：
10.1121/1.4812878
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发表时间：
2013-08-01
影响因子：
2.4
通讯作者：
Shaw, Adam
中科院分区：
文献类型：
--
作者：
Khokhlova, Vera A.;Shmeleva, Svetlana M.;Shaw, Adam
利用红外（IR）技术对高强度聚焦超声（HIFU）换能器的声场进行定性测绘已经取得了相当大的进展。作者之前已经开发并演示了一种基于红外相机测量的方法，该方法通过持续时间少于1秒的超声波爆发来测量厚度小于2mm的吸收体中引起的温升。本文的目的是使该方法更加定量，并通过确定吸收器和相机系统的总体校准因子来估计绝对强度分布。所实现的方法涉及将使用红外相机在吸收器中测量的温升与使用水听器在水中测量的压力分布相关联。测量是对两个HIFU换能器和一个1MHz频率的平板物理治疗换能器进行的。得到了自由场强度与温度之间的相应校正因子，并将温度图像转换为强度分布。这里描述的系统能够很好地绘制亚毫米结构的聚焦和非聚焦超声场，当地时间平均强度从低于0.1 W/cm(2)到至少50 W/cm(2)。简单地通过减小占空比就可以测量到明显更高的强度。(C) 2013年美国声学学会。
Considerable progress has been achieved in the use of infrared (IR) techniques for qualitative mapping of acoustic fields of high intensity focused ultrasound (HIFU) transducers. The authors have previously developed and demonstrated a method based on IR camera measurement of the temperature rise induced in an absorber less than 2mm thick by ultrasonic bursts of less than 1 s duration. The goal of this paper was to make the method more quantitative and estimate the absolute intensity distributions by determining an overall calibration factor for the absorber and camera system. The implemented approach involved correlating the temperature rise measured in an absorber using an IR camera with the pressure distribution measured in water using a hydrophone. The measurements were conducted for two HIFU transducers and a flat physiotherapy transducer of 1MHz frequency. Corresponding correction factors between the free field intensity and temperature were obtained and allowed the conversion of temperature images to intensity distributions. The system described here was able to map in good detail focused and unfocused ultrasound fields with sub-millimeter structure and with local time average intensity from below 0.1 W/cm(2) to at least 50 W/cm(2). Significantly higher intensities could be measured simply by reducing the duty cycle. (C) 2013 Acoustical Society of America.