Acoustic saturation and output regulation
Acoustic saturation and output regulation
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DOI：
10.1016/s0301-5629(99)00038-1
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发表时间：
1999-07-01
影响因子：
2.9
通讯作者：
Duck, FA
中科院分区：
文献类型：
--
作者：
Duck, FA
针对一定频率和焦深范围的超声波束预测声学饱和压力，使用合理的近似计算机械指数（MI）的饱和值以及降低的空间峰值、时间平均和脉冲平均强度。这些都是比较阈值设置的监管目的，由美国。S.美国食品药品监督管理局（FDA）和国际电工委员会（IEC）。得出的结论是，有许多条件下，在水中的声饱和防止MI值和规定的强度超过由FDA设定的阈值，这些条件是特别与较高的频率和较深的焦距。IEC 61157设定的动作阈值足够低，不会出现类似问题。它的结论是，目前的法规是不完全有效的限制从诊断超声设备的输出，并存在一些条件是不受输出控制。(C)1999年世界医学和生物学超声联合会。
Acoustic saturation pressures are predicted for ultrasonic beams of a range of frequencies and focal depths, Using reasonable approximations, saturation values for mechanical index (MI) and derated spatial-peak, time-average and pulse-average intensities are calculated. These are compared with thresholds set for regulatory purposes by the U. S. Food and Drug Administration (FDA), and by the International Electrotechnical Commission (IEC). It is concluded that there are many conditions for which acoustic saturation in water prevents the values of MI and regulated intensities from exceeding thresholds set by the FDA, These conditions are particularly associated with higher frequencies and deeper focal lengths. The thresholds for action set by IEC 61157 are sufficiently low that similar problems do not arise. It is concluded that present regulations are not fully effective in limiting the output from diagnostic ultrasound equipment, and that some conditions exist that are not subject to output control. (C) 1999 World Federation for Ultrasound in Medicine & Biology.