【作者】 刘力； 王燕芳；

【Author】 Liu Li Wang Yanfang (Institute of High Energy Physics,CAS,Beijing 100049,China)

【机构】 中国科学院高能物理研究所；

【摘要】 目的建立扇束工业 CT 模拟重建计算平台,通过模拟计算方法,在不同的扫描几何,不同探测器数目,不同投影角度情况下,研究计算扇束工业 CT 的重楚田像质量及多种误差引起的图像伪影。方法利用先进的计算机技术,针对具体扇束工业 CT 扫描几何及其对称性,生成并储存巨大的扫描几何地址参数矩阵,然后经前投影计算得到任意模型的模拟投影(SINO)数据,最终进行图像重建获得断层影像。在生成 SINO 图时可人为加入几何等误差,在重建后的图像上观察由此产生的伪影表现。结果对光源位置引起的几何误差、线阵探测器倾斜误差、转台机械误差等进行了模拟计算,结果表明,旋转中心的微小偏移误差会导致整个图像的空间分辨交差,角度上的误差可导致大工件边缘处图像的模糊并产生特有的花瓣状伪影等。结论该扇束工业 CT 模拟重建计算平台可用以工业 CT 的扫描模式的设计及其误差分析,可对单个误差因素进行逐个研究,也可进行多误差合成研究,有助于发现导致伪影的误差来源并进行有效的校正,提高扇束工业 CT 的成像质量。更多还原

【Abstract】 Objective The simulated image reconstruction platform for fan-beam industrial CT was set up,by which one can calculate and study the artifacts in CT images under different scanning geometries,different detector arrangement,different angle sampling.Method Using compu- ting techniques and the symmetry properties in fan-beam CT scanning modes,the huge parameter matrix was calculated and saved in PC,so the projective data (sonogram) of a stimulated phantom can be carry out and then be reconstructed to get the CT images.In creating the sonogram,va- rious errors can be introduced,such as geometry error in CT set,etc. Results The CT artifacts were created and analyzed,which were caused hy the error of X-ray spot positioning,oblique of detector line,the rota- ting error,etc.The results showed that:the tiny deviation of the rotating center can seriously worsen the spatial resolution,the angular error can lead to"flower"artifacts for the small work-pioce located at large distance apart from the center,etc.Conclusion Using the proposed CT recon- struction platform,the various errors (single or multiple) can be artifi- cially added,and the resultant artifacts can be shown and analyzed.This function can help us in designing industrial CT and finding/correcting the artifacts in CT images.更多还原