University of Rijeka, Faculty of Medicine, Department of Medical Physics and Biophysics, Braće Branchetta 20, 51 000 Rijeka, Croatia; University of Rijeka, Department of Physics, Radmile Matejčić 4, 51 000 Rijeka, Croatia.
Clinical Hospital Center Rijeka, Krešimirova 42, 51 000 Rijeka, Croatia.
Ultrasonics. 2019 Nov;99:105943. doi: 10.1016/j.ultras.2019.06.005. Epub 2019 Jul 15.
The evaluation of the performance of nine physiotherapy ultrasound transducers used clinically was performed in the hospital environment using an acoustically absorbing thermocromic tile developed at the National Physical Laboratory (UK). The method consists of exposing an acoustic absorber tile, part of which contains a thermochromic pigment, to the ultrasonic beam, thereby forming an image of the intensity profile of the transducer. Images acquired using thermochromic materials were postprocessed in order to estimate effective radiating area (ERA) and beam nonuniformity ratio (BNR) for ultrasound transducers operating within the frequency range from 1.0 to 3.3 MHz, and nominal applied intensities in the range of 1-2W/cm. Results of our measurements have shown that thermocromic tile can be used for quality control of ultrasound transducers in the hospital environment. Experimental results show that proposed method can be used to distinguish highly non - uniform ultrasound beams with high value of BNR. Influence of exposure duration on obtained ERA and BNR values was also analysed. Our results show that values for ERA increase with insonation time, while BNR values decrease. In order to compare our results with theory we have estimated temperature rise in thermochromic material experimentally and compare it with theoretical prediction.
在医院环境中，使用英国国家物理实验室（National Physical Laboratory，简称 NPL）开发的吸声热致变色瓷砖，对九种临床使用的物理治疗超声换能器的性能进行了评估。该方法包括使声吸收瓷砖的一部分暴露于超声射束中，其中包含热致变色颜料，从而形成换能器强度分布的图像。使用热致变色材料获得的图像经过后处理，以估计在 1.0 至 3.3 MHz 的频率范围内以及 1 至 2 W/cm 的名义应用强度下工作的超声换能器的有效辐射面积（Effective Radiating Area，简称 ERA）和波束不均匀性比（Beam Nonuniformity Ratio，简称 BNR）。我们的测量结果表明，热致变色瓷砖可用于医院环境中超声换能器的质量控制。实验结果表明，该方法可用于区分具有高 BNR 值的高度不均匀超声束。还分析了曝光持续时间对获得的 ERA 和 BNR 值的影响。我们的结果表明，ERA 值随照射时间的增加而增加，而 BNR 值则减小。为了将我们的结果与理论进行比较，我们通过实验估计了热致变色材料中的温升，并将其与理论预测进行了比较。
