Straub Stephen J, Johns Lennart D, Howard Samuel M
Department of Physical Therapy, Quinnipiac University, 275 Mt Carmel Ave FOTRN, Hamden, CT 06489, USA.
Phys Ther. 2008 Jan;88(1):50-7. doi: 10.2522/ptj.20060358. Epub 2007 Oct 16.
Previous research has indicated that not all ultrasound transducers heat at equal rates; however, the cause of this disparity is unclear. Variability in spatial average intensity (SAI) has been implicated in this disparity at 3 MHz. This variability has not been explored at 1 MHz.
Sixty-six 5-cm(2) ultrasound transducers were purchased from 6 different manufacturers. Transducers were calibrated and assessed for effective radiating area (ERA), total output power, and SAI using standardized measurement techniques.
Total output power values fell within US Food and Drug Administration guidelines, but there were large variations in ERA. The resulting SAI values showed large deviations (-43% to +61%) from the digitally displayed value. Intra-manufacturer SAI values varied up to 53%.
Spatial average intensity can vary largely from the values displayed on these ultrasound generators; in a calibrated cohort, this difference is primarily attributable to differences in measured ERA. Patterns of SAI variability within the manufacturer at 1 MHz do not follow previous reports of variability at 3 MHz.
先前的研究表明，并非所有超声换能器的发热速率都相同；然而，这种差异的原因尚不清楚。空间平均强度（SAI）的变化被认为与3兆赫时的这种差异有关。1兆赫时的这种变化尚未得到研究。
从6个不同制造商处购买了66个5平方厘米的超声换能器。使用标准化测量技术对换能器进行校准，并评估其有效辐射面积（ERA）、总输出功率和SAI。
总输出功率值在美国食品药品监督管理局的指导范围内，但ERA存在很大差异。由此产生的SAI值与数字显示值有很大偏差（-43%至+61%）。制造商内部的SAI值差异高达53%。
空间平均强度可能与这些超声发生器上显示的值有很大差异；在校准队列中，这种差异主要归因于测量的ERA差异。1兆赫时制造商内部SAI变化模式与先前3兆赫时的变化报告不同。
