将计算机断层扫描技术(CT)应用到树木的无损检测领域,设计基于不同CT参数扫描树木成像效果的比照试验,探索树木检测的CT参数阈值设定与优化。具体步骤与方法:1)采集12份树木圆盘标本,每份样木根据不同的CT参数设置拍摄200张影像;2)将不同成像完整度的影像进行分组归类后,对影像灰度值进行提取并得到各幅影像灰度值均值、灰度值标准差;3)利用SPSS软件统计分析CT参数与影像完整度间的关联性,并得到影响树木成像效果的关键参数设置阈值范围。结果显示:CT扫描树木成像清晰,其参数毫安秒(mAs)、定点位置(SP)间的相关性为0.972,影像完整度75%以上的mAs阈值区间为47~61,SP阈值区间为-66.4~-89.8。采集3份不同古树的标本,应用实验获得的CT参数阈值对标本进行扫描,以验证CT参数阈值选定的合理性。结果表明:所选CT参数阈值范围对于树木个体不存在明显的树种差异,可以满足树木无损检测要求。

Using computed tomography(CT) technology in the field of non-destructive detection of trees,the paper designed a comparison test based on the imaging effect of different CT parameters,and explored the setting and optimization of the threshold of CT parameters for tree detection.Specific steps and methods:1) collect 12 specimens of tree discs,each sample takes 200 images according to different CT parameters;2) After grouping the images with different imaging integrity,the gray value of the image is extracted and the average gray value and standard difference of gray value of each image are obtained;3) using SPSS software to analyze the correlation between CT parameters and image integrity,and obtain the key parameters that affect the imaging effect of trees to set the threshold range.The results showed that the imaging of CT scanning trees was clear,the correlation between the parameters mAs and SP was 0.972,and the threshold range of mAs with an image integrity of more than 75% was 47 to 61.The SP threshold range is -66.4~-89.8.Three specimens of different ancient trees were collected,and the CT parameter threshold obtained by the experiment was used to scan the specimens to verify the rationality of the selection of CT parameter threshold.The results show that there is no obvious tree species difference in the range of selected CT parameters,which can meet the requirements of non-destructive testing of trees.