管道内部X射线背散射成像可行性分析

利用无损检测手段确保石油管道安全高效地输送石油意义重大。X射线背散射成像系统凭借其单侧布置优势具有在管道内部进行缺陷检测的潜力。采用蒙特卡洛软件（Geant4）建立了管道内部X射线背散射成像系统模型，该系统由X射线管，可旋转准直器，可旋转探测器等部分组成，其采用飞点扫描方式。进一步研究了X射线管管电压、能谱和X射线笔形束束斑大小对检测性能的影响。研究结果表明，管道内壁的检测厚度有限，并非管电压越高检测厚度就越厚，对15 mm厚度以内的管壁检测，管电压适合采用300 kV；X射线管适合采用标准窄谱；束斑直径根据图像对比度成与直径之间的线性关系确定。该系统能够有效的用于管道内部缺陷定位和识别，具有工业应用的可行性。

Feasibility Analysis of X-ray Backscatter Imaging Inside Pipeline

It is of great significance to ensure the safe and efficient transportation of petroleum by non-destructive testing. X-ray backscatter imaging system has the potential for defect inspection inside the pipeline due to its advantage of single-sided layout. In this paper, the Monte Carlo software (Geant4) has been used to establish the model of X-ray backscatter imaging system in the pipeline. The system is composed of X-ray tube, rotatable collimators, rotatable detectors and other parts. The flying point scanning mode is adopted. Furthermore, the influence of X-ray tube voltage, energy spectrum and X-ray pencil beam spot size on the detection performance was studied. The results show that the detection thickness of the inner wall of the pipeline is limited, not that the higher the tube voltage is, the thicker the detection thickness is. For the detection of the pipe wall within the thickness of 15 mm, the X-ray tube voltage is suitable to configure with 300 kV. X-ray tube with standard narrow spectrum is better to be used. The pencil beam spot diameter is determined according to the relationship between the detection image contrast and the diameter. The system can be effectively used to locate and identify the internal defects of the pipeline, and has the feasibility of industrial application.