Study On The Key Technolgies Of Portable Low Intensity X-ray Real-time Imaging Systems

X-ray non-destructive inspection has been applied in the industry for a long time. The early shooting method has many limits in the application for long time-consuming, high cost and no-real-time. With the development of the computer imagery processing technology, the X-ray real-time imaging system has developed rapidly for several years. The X-ray real-time imaging system combines X-ray image formation technology with the computer imagery processing technology. The examination speed is quick. Compared with the traditional shooting method, the X-ray examination efficiency is raised enormously, which reduces the examination cost. The examination data is easy to preserve and inquiry. The dynamic effect of the X-ray real-time imaging system is much better than that of the traditional shooting method. As the traditional X-ray real-time imaging system includes the electrostatic focusing type X-ray image intensifier with big volume, it can only be applied in stationary system.The proximity type X-ray image intensifier promoted the development of the portable low intensity X-ray image system, including the small table model X-ray image device and the hand-grasp type X-ray image device. The portable low intensity X-ray image device is low power cost, easy protection and easy visual observation in the bright environment, providing the important method for the medical domain clinical examination, real-time inspection of the athletic field and Field forces; Meanwhile, it is also widespread applied in non-destructive inspection of the small-scale industry product and the security check of security department. However, the X-ray phantom system image quality is poor and the systematic research on improving the image quality is little. In recent years, the study of image gathering processing technology is limited to the method of the large X-ray real-time imaging system, without the function of the portable real-time imagery processing.The portable X-ray real-time image system includes the X-ray source, the single proximity type X-ray image intensifier, CCD, and the image collection and processing device. It belongs to the series connected image system, in which any link with the low performance will become the bottleneck of restricting the system performance. To improve the image quality of the portable low intensity X-ray real-time imaging system and develop its application space, the following research works are carried out in this thesis:1 The reason of fuzzy X-ray image and the processing method. Using the Tracepro software, the X-ray geometry image formation performance is evaluated, providing one kind of low cost highly effective solution to the system design for X ray tube; Micro channel plate (MCP), as the absorption type collimator, is studied theoretically and experimentally. The ideal result is obtained. The MCP collimator has small volume, the light weight, which is very suitably in application in portable X-ray phantom system.2 The cathode of the single proximity type X-ray image intensifier is researched. The ideal film structure is obtained. The electron scattering from surface is simulated with the Monte Carlo method, indicating that the electron scattering in the cathode is a key factor on the image resolution of the proximity type X-ray image intensifier. The auxiliary accelerating electric field is proposed to reduce the out-coming electron dissemination radius.3. The single proximity type X-ray image intensifier and the influence factors of CCD noise are studied. In the real-time imaging system for CCD image gathering, the working voltage of MCP the method is reduced to decrease the image noise of the X-ray image intensifier. The refrigerated CCD is used to reduce the noise in the image gathering process, reducing 6 times of the CCD background noise. The match of the X-ray image intensifier to the CCD resolution is studied, presenting the optimal matched data.4 The spatial resolution of the portable X-ray real-time imaging system and the request for contrast sensitivity is taken into account. The method of two-step image processing, including the image noise reduction and the image enhancement, is studied. The image noise reductions are processed from the aspects of frequency region, the time frequency region and the spatial filtering, separately. The filtering in the time frequency range plays a key role on the X-ray image. After studying each kind of image enhancing algorithms, Gray value variance is adopted to compress the contrast stretching transformation in the enhancement region, strengthening the X-ray image with low contrast effectively.5 Based on NIOSⅡThe FPGA platform, DSP IP soft nucleus and the imagery processing soft nucleus are designed. The parallel structure of the imagery processing is realized. The processing speed is raised. The portable real-time imagery processing function is realized.After optimizing various parts of the system, the resolution of 6.31p/mm is realized in the X-ray real-time imaging system of single proximity focus, reaching the level of a linear array and planar array level abroad.Finally, the research work was summarized. The prospects for further work were also proposed.