The Design And Implementation Of The Radiography Acquisition System Based On FPGA

At present,X-ray radiography security inspection system is widely used in domestic airports,railways,customs,ports and other places,which is widely used,but the domestic independent research and development of digital radiography security inspection equipment less.As an important means of public safety inspection,FPGA-based radiography acquisition system uses X-ray scanning graphy technology to quickly scan luggage,containers,and detect drugs,firearms,explosives,etc dangerous contraband and smuggled goods,and preserve personal and property security,and ensure social peace and tranquility.According to the randomness and statistical characteristics of the nuclear pulse signal,this paper focuses on the mechanism of the interaction between the X-ray and the cesium iodide crystal,and mastered the processing method of the array detector for the nuclear pulse signal.In this paper,the design of the X-ray array detector signal acquisition subsystem is completed,and the design and debugging of the pulse signal extraction,integral amplification,difference filtering,AD conversion and FPGA-based radiography data acquisition board are completed.The use of embedded experimental board to build array detector pulse signal acquisition and test platform,the preparation of pulse counting curve rendering software,the use of digital oscilloscope to observe the pulse signal.The "trailing" phenomenon of pulse signal is analyzed qualitatively by theoretical method,and the pulse signal is filtered,the baseline recovery and the sliding mean filter are processed.For the FPGA-based kernel design of the data acquisition and transmission controller,this paper completes the state transfer control process and Verilog HDL kernel design of the integral transformation timing control logic module,LVDS data transmission module,RAM memory module,RAM read and write timing control module,and VGA timing control module,and use the Signal Tap II logic analyzer to design the various logic modules for timing verification.In this paper,the image processing algorithm is studied and the mathematical model of linear interpolation algorithm is established,which is based on the nonuniformity of the beam intensity of the X-ray fan and the inconsistency of the parameters of the array detector circuit.The algorithm of linear interpolation algorithm is designed,and the image processing verification platform is built,and the effect of image processing is analyzed.The results show that X-ray pulse signal acquisition,data transmission,image processing and VGA video display function are realized by FPGA-based radiography acquisition system.After the filter forming method is used,the "trailing" phenomenon of the array detector signal output disappears and the pulse count capacity is increased.Using the "pole-zero" cancellation method,the undershoot phenomenon of the pulse signal also disappears and reduces the effect of the positive electric field signal.Through the system verification and algorithm improvement,the image shading level faint disappeared,the image quality has also been improved.FPGA-based radiography acquisition system in the practical application of the basic meet the design requirements,has a high application value.