Hynynen K, Davis K L
Arizona Cancer Center, Tucson.
Int J Hyperthermia. 1993 Mar-Apr;9(2):263-74. doi: 10.3109/02656739309022539.
In this study, small (outside diameter 1 mm) cylindrical ultrasound sources were investigated for induction of hyperthermia in tumours. These ultrasound transducers could be placed in small-diameter body cavities, or they could be used interstitially in brachytherapy catheters. The ultrasound field measurements showed that the field is fairly uniform as a function of the length of the applicator except at the ends where sharp peaks were located. However, there were significant field variations as a function of rotation angle around the transducers. The degree of these non-uniformities varied from transducer to transducer, and also as a function of frequency. The temperature measurements in vitro perfused kidneys showed that therapeutic temperature elevations could be induced in perfused tissues. The radial extent of the therapeutic zone could be increased by circulating water around the applicators, thus avoiding high temperatures on the applicator surface. It was also shown that some control over the temperature distribution along the length of the applicator could be achieved by using a two-element applicator. An array of four applicators implanted in a square pattern with the spacing of 25 mm between the catheters, was able to heat the tissue volume inside of the implant. The results showed that these small ultrasound applicators may offer significant improvement over existing techniques by increasing the penetration depth and the control over the power deposition pattern.
在本研究中，对小型（外径1毫米）圆柱形超声源进行了研究，以诱导肿瘤内热疗。这些超声换能器可放置在小直径体腔内，或用于近距离治疗导管的间质内。超声场测量表明，除了在存在尖锐峰值的端部外，场随施源器长度的变化相当均匀。然而，场随围绕换能器的旋转角度存在显著变化。这些不均匀性的程度因换能器而异，也随频率而变化。体外灌注肾脏的温度测量表明，可在灌注组织中诱导出治疗性的温度升高。通过在施源器周围循环水，可增加治疗区域的径向范围，从而避免施源器表面出现高温。还表明，使用双元件施源器可对沿施源器长度方向的温度分布进行一定程度的控制。以导管之间25毫米的间距呈方形排列植入的四个施源器阵列，能够加热植入物内部的组织体积。结果表明，这些小型超声施源器通过增加穿透深度和对功率沉积模式的控制，可能比现有技术有显著改进。
