Malyarenko Eugene V, Heyman Joseph S, Chen-Mayer H Heather, Tosh Ronald E
Luna Innovations Incorporated, Hampton, Virginia 23666, USA.
J Acoust Soc Am. 2008 Dec;124(6):3481-90. doi: 10.1121/1.2997431.
This paper describes recent developments in the area of high-precision ultrasonic thermometry with the potential to provide on-site direct determination of radiation doses administered for cancer treatment. Conventional calorimeters used for this purpose measure radiation-induced heating in a water phantom at one point in space by means of immersed thermistors and are subject to various thermal disturbances due to Ohmic heating and interactions of the radiation with the sensor probes. By contrast, the method described here is based on a high-resolution ultrasonic system that determines the change of the speed of sound due to small temperature changes in an acoustic propagation path in the radiation-heated water, thereby avoiding such undesired thermal effects. The thermometer is able to measure tens of microkelvin changes in the water temperature averaged over the acoustic path of about 60 cm at room temperature, with root-mean-squared noise of about 5 microK. Both incandescent and ionizing radiation heating data are presented for analog and digital implementations of a laboratory prototype. This application of the ultrasonic technique opens up possibilities for a new approach to performing therapy-level radiation dosimetry for medical clinics and standards laboratories.
本文描述了高精度超声测温领域的最新进展，该技术有可能实现现场直接测定癌症治疗中所施用的辐射剂量。用于此目的的传统量热计通过浸入式热敏电阻在空间中的某一点测量水模体中辐射诱导的加热，并且由于欧姆加热以及辐射与传感器探头的相互作用而受到各种热干扰。相比之下，这里描述的方法基于高分辨率超声系统，该系统通过辐射加热水中声传播路径中的小温度变化来确定声速变化，从而避免了此类不良热效应。该温度计能够在室温下测量约60厘米声程上平均水温的数十微开尔文变化，均方根噪声约为5微开尔文。给出了实验室原型的模拟和数字实现方式下的白炽辐射和电离辐射加热数据。超声技术的这种应用为医疗诊所和标准实验室进行治疗级辐射剂量测定开辟了新途径。
