Nakayama M, Tanishita K
Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Yokohama, Japan.
Biomed Mater Eng. 1994;4(2):105-14.
This study propose a new simple method of measuring the thermal diffusivity of living tissue by thermal pulse decay technique with focused ultrasonic beam, which does not require the accurate knowledge of Gaussian variance within the focal region. The measurement of temperatures at two different locations outside the focal region replaces the elaborate measurement of the size of the focal region and gives a thermal diffusivity with reasonable accuracy and automatically avoids the artifact due to beam-thermocouple interaction. The focused ultrasound was generated by the bowl-shaped ceramic piezoelectric transducer with the diameter of 30 mm. The focal lengths of transducer were 40 mm and 60 mm and the frequencies 1.7 and 3.6 MHz. The values of thermal diffusivity of biological tissues obtained in this method are fairly close to the previously published values and are also compared to the values obtained by heated thermistor method.
本研究提出了一种通过聚焦超声束热脉冲衰减技术测量活组织热扩散率的新的简单方法，该方法不需要精确了解焦区内的高斯方差。在焦区外两个不同位置测量温度取代了对焦区大小的精细测量，并能以合理的精度给出热扩散率，且自动避免了由于束 - 热电偶相互作用产生的伪影。聚焦超声由直径为30mm的碗形陶瓷压电换能器产生。换能器的焦距分别为40mm和60mm，频率分别为1.7MHz和3.6MHz。用该方法获得的生物组织热扩散率值与先前发表的值相当接近，并且还与通过加热热敏电阻法获得的值进行了比较。
