教学用工业CT实验仪器的设计与开发研究

Development of computed tomography instrument for college teaching

计算机层析成像(CT)技术采用射线从多个角度穿透物体来重建断层图像或三维图像,该技术已经广泛地应用于医学诊断和治疗、工业无损检测和无损评价。因此,对于大学学生来讲,了解和掌握CT技术的基本原理具有重要意义。本文详细介绍了用于大学教学的CD-50BG型CT实验仪。该仪器采用“平移+旋转”的扫描方式,具有活度为0.74GBq的Csγ射线源、单个塑料闪烁体+光电二极管的探测器和50mm的视场137直径,其中射线源安装在钨合金的屏蔽容器中。同时,开发了图像处理软件对采集数据进行处理,重建断层图像和重构三维图像。重建断层图像可达到1lp/mm的空间分辨率和1%的密度分辨率。目前,已经有包括清华大学、北京大学在内的十余所高校将该仪器用于基础教学。

Computed tomography （CT）, which uses penetrating radiation from many directions to reconstruct cross-sectional or 3D images of object, has widely applied in medical diagnosis and treatment, industrial NDT and NDE. So it is significant for college students to understand the fundamental of CT. In this article we describe the CD-50BG CT instrument developed for experimental teaching at colleges. With 50 mm field-of-view and the translation-rotation scanning mode, the system makes use of a single plastic scintillator ＋ photomultiplier detector and a 137^Cs radioactive source with 0.74 GBq activity, which is housed in a tungsten alloy shield. At the same time, an image processing software has been developed to process the acquired data, so that cross-sectional and 3D images can be reconstructed. High quality images with 11p·mm^-1 spatial resolution and 1% contrast sensitivity are obtained. So far in China, more than ten institutions including Tsinghua University and Peking University have a/ready applied the system to elementary teaching.