Diagnosis of Temperature Field by Ultrasonic CT-In case of limited projection angle

超声波CT作为一种热测量方法 ,具有不接触、对温度场不干扰的优点。本文发展一种新的超声波CT再现方法 ,用于解决受限透视角度所产生的信息量不足的问题。新的超声波CT再现算法建立在逆矩阵变换的基础上 ,它不同于通常的采用SL过滤器的所谓FBPCT再现方式。论文中描述了三种CT迭代再现算法 ,用计算机模拟结果和三维温度场测量实验数据验证了再现算法的可靠性。同时根据计算和实验结果 ,建议在受限的透视角度情况下 。

Ultrasonic CT has been applied to thermal environmental measurements as a kind of nonintrusive method. This research tries to develop a new ultrasonic CT reconstruction method to deal with problems such as having not enough projection data due to limited projection angle. The new CT reconstruction algorithm is based on inverse matrix transformation which differs itself from the ordinary CT reconstruction, known as FBP(Filtered Back Projection) with SL Filter. In current paper, 3 kinds of iterative CT reconstruction algorithms are described. Computer simulations were conducted to verify the above algorithms and the reconstruction results were compared. An experiment on 3D temperature distribution measurements was carried out to validate the proposed algorithms. According to the simulation and experimental results, improved CGM (Conjugate Gradient Method) taking consideration of regularized least squares was suggested to be the optimum iterative way for CT reconstruction under the condition of limited projection angle.