Fast Acquisition Of Structural Parameters Of Vehicular High-precision Industrial CT

Cone beam industrial CT technology,as a new technology that can serve for national defense,military industry and industry,is the focus of CT research in recent years.The vehicle mounted high-precision industrial CT system is a cone beam industrial CT detection system developed by Beijing Key Laboratory of nuclear detection technology of Tsinghua University.Because of the actual requirements,the vehicle mounted high precision industrial CT system needs to be transported to the designated place to carry out the detection work quickly,but the long distance transportation may affect the adjusted structural parameters.In order to ensure the quality of CT image reconstruction,a method to obtain structural parameters which can meet the requirements of actual engineering precision should be designed.This method should be fast,concise,high precision,easy to operate and minimize manual intervention.The existing parameter acquisition methods at home and abroad are insufficient to meet these requirements.In this paper,we analyze the influence of the structure parameters of high precision industrial CT on the reconstructed image quality from two aspects of theoretical derivation and experimental research,and determine the order of the importance of obtaining the parameters and the acquisition precision of each parameter.Then we design a new method to obtain the structure parameters,named “the parallel double-wire” method,which meets the actual engineering requirements.The parallel double-wire is used as the model body,and the projective image of 360 degrees is obtained by rotating the mould body for one circle in use,and four structural parameters,such as the distance of the source detector,the distance between the source and rotation center,the projection axis of the rotating center,the angle of the rotation of the detector around the Y axis,can be obtained accurately.The parallel double-wire module is simple and easy to operate.The results show that the method has good robustness.To ensure the parallel double-wire method can be used well in engineering practice,this paper designs the model structure and analyzes material selection of the parallel double-wire method,and finally makes the actual mould,and then carries out the experimental research on the high precision industrial CT system on the vehicle.The experimental results show that the parallel double-wire method and the designed die body can accurately obtain the structural parameters of the actual high precision CT system,and the clear fault images can be reconstructed based on these parameters.In order to further improve the accuracy of parallel double wire method and reduce the degree of manual intervention,the parallel double wire method is studied in this paper.By analyzing the gray value of the double filament projection,using the characteristics of the difference of the gray value of the filament projection,the waveform analysis method is proposed to deal with the parallel double-wire projection data.Then the complete automation of the parallel double wire method from the experimental operation to the data processing is realized,and the artificial dependency of structure parameter acquisition of vehicle high-precision industrial CT system is greatly reduced.Finally,the sampling time of the parallel double-wire method is optimized.By reducing the time of the single projection and reducing the total sampling number,the sampling time is shortened,and the data fitting method is used to ensure the accuracy of the result.Then the method is speeded up.Finally,the method meets all the engineering requirements of vehicle mounted high-precision industrial CT.