基于阵列式吸收发光CT法的辐射场实时测量系统的研究

The Study of Real Time Radiography System Based on Array Absorption Emission Computed Tomography

分析了已有的各种核辐射剂量场测量方法的基础上， 利用闪烁体吸收发光特点并结合计算机实时成像处理技术，提出了对剂量场分布进行实时成像测量的新方法——阵列式吸收发光ＣＴ 法。研制出闪烁光纤阵列构成的探测器及其伺服控制系统， 用高灵敏度的电荷耦合器件（ＣＣＤ）拾取探测器产生的微弱闪烁光信号，并采用定点采集的方法对视频信号进行数据的快速采集。在图像重建方法上， 提出了迭代滤波反投影重建方法和利用非完全投影进行数据修复，对获取的投影数据进行变换和处理，并通过选择滤波函数及其适当的参数， 可获得最佳滤波效果，以重建剂量场的二维场分布，从而建立了剂量场的实时、高精度的成像测量系统。

By the comprehensive analysis of existing measuring methods, a new method is proposed in the paper to measure the nuclear radiation dose field with array absorption emission computed tomography. The detector based on scintillation optical fiber array and its servo control system are designed. The weak optical signal is measured by Charge Coupled Devices (CCD) and the formed visual signal is quickly sampled with the method of testing fixed signed points. The recostruction method of iterative filter back projection and the data renovate based on noncomplete projection are proposed to reconstruct dose field more accurately. The filter function is also an important factor in the image reconstruction. The Butterworth filter function is chosen. By adjusting its parameters, we have obtained optimum result. Finally, all the experimentation shows that the methods proposed in paper are proper and whole measuring system is advanced and feasible.