Herman Bruce A, Harris Gerald R
Center for Devices and Radiological Health, Food and Drug Administration, Rockville, MD, USA.
Ultrasound Med Biol. 2002 Sep;28(9):1217-24. doi: 10.1016/s0301-5629(02)00558-6.
A new diagnostic ultrasound (US) technique, sometimes called radiation force imaging, produces and detects motion in solid tissue or acoustic streaming in fluids via a high-intensity beam. Current models for estimating temperature rise during US exposure calculate the steady-state rise, using time-averaged acoustic output, as the worst case for safety consideration. Although valid for very short pulses, this analysis might not correspond to a worst-case scenario for the longer pulses or pulse bursts, up to hundreds of ms, used by this newer method. Models are presented to calculate the transient temperature rise from these pulse bursts for both the bone at focus and soft tissue situation. It is shown, based on accepted time-temperature dose criteria, that, for the bone at focus case and pulse lengths and intensities utilized by these methods, temperature may increase to levels that raise safety concerns. Also, regulatory aspects of this modality are analyzed in terms of the current FDA acoustic output limits for diagnostic US devices.
一种新的诊断超声（US）技术，有时称为辐射力成像，通过高强度光束在固体组织中产生并检测运动或在流体中检测声流。当前用于估计超声暴露期间温度升高的模型使用时间平均声输出计算稳态升高，将其作为安全考虑的最坏情况。尽管该分析对于非常短的脉冲有效，但对于这种新方法使用的长达数百毫秒的较长脉冲或脉冲串，该分析可能并不对应于最坏情况。本文提出了模型，用于计算聚焦处的骨骼和软组织情况下这些脉冲串引起的瞬态温度升高。结果表明，根据公认的时间-温度剂量标准，对于聚焦处的骨骼情况以及这些方法使用的脉冲长度和强度，温度可能会升高到引发安全担忧的水平。此外，还根据美国食品药品监督管理局（FDA）目前对诊断超声设备的声输出限制，对这种模式的监管方面进行了分析。
