Imaging Algorithm Construction And System Research And Development Of Wood X-ray Tomography Scanning

CT technology is a nondestructive testing technology to rebuild a cross section image by getting ray projections of the object from different angles, which has excellent using effects in healthcare, industry and agriculture. This article builds a wood tomography CT system based on imaging principle and method of industrial CT technology, and makes a detailed description and analysis in hardware constitution, image reconstruction algorithm, software development and application example aspects.The hardware of this system is the principle of this nondestructive testing equipment, which mainly consists of a fan-shaped X-ray emitter, an equidistance flat-panel detector, as ample support, a computer, a carrier vehicle and a protection system. Three former constitute a data acquisition system. Unlike medical CT, the transmitter and the detector are fixed in-place, and the central sample rotates uniformly with its support to gather and store projection data from different angles. Lead chambers and protective clothing of protection system can shield operators from X-ray radiation.Image reconstruction algorithm leads to the quality and efficiency of CT imaging system, which is an important part of this research, and it mainly divides into algebraic iteration and back projection imaging method at present. According to CT imaging principle, a fast back projection coordinate algorithm based on convolution back projection reconstruction algorithm is proposed. This algorithm consists of projection coordinates calculation, projection data acquisition and storage, projection data processing and smoothing back projection calculation. Projection coordinates are calculated once and stored only at the first imaging reconstruction. By using the coordinates people can extract homologous projection data directly and calculate convolution with filtering function each time later, so as to complete imaging reconstruction and improve computing efficiency. Single image only reflects fault structure from one angle, so this system scans multiple faults and uses evenly spaced intercalation to rebuild three-section images and perspectives drawing, which can show an omnibearing observation of the internal wood structure.The software is used to realize image reconstruction algorithm, and its compatibility and efficiency determine the feasibility and availability. This system is based on C + + language and programed in Windows system via Visual Studio 2010. The realization of each function block mainly lies in extension of the fast back projection algorithm and processing and analysis of images reconstructed. The overall software function framework is divided into five modules, which are data acquisition and storage, back projection imaging, image processing, image analysis and storage and color palette module. Each module also has a number of dialog boxes to achieve the homologous sub function of each module. Packaging for this software is also provided to give users better visual and operational experience, such as the main interface beautification, optimizing of startup interface and helping system, etc.To detect feasibility and availability of the wood testing tomography CT system, it is necessary to choose a variety of wood material of different properties, structure, shapes and sizes for scanning experiment and example analysis, and to elaborate test results from rotation center correction, transverse section image reconstruction, sinusoidal image reconstruction, three-section view and perspective drawing. The results show that the reconstructed images are of high definition, the image measurement error range is within 1%, and the three-section view and perspective drawing provide a reliable basis for observation and orientation of internal defects of wood.This paper aims to research and develop a wood tomography CT system, and detailedly describe the developing process and method, and finally prove its feasibility and availability through application examples. This system can play a significant role in wood scientific research, wood nondestructive detection and wood processing and utilization fields.