关键词: CT扫描, 频谱分析, 图像重建, 投影向量, 傅里叶级数

Abstract: The scanning measurement in optical CT calculates the length of ray across the pixel rapidly and accurately by using the coordinate intersected by the ray and the parallel to the reference frame.In frequency spectrum analysis for image reconstruction，this length is used to compute the projection vector of the original image，and afterwards，establish the firm ground for the reconstruction image approaching the original image.The computer simulation shows that this measurement speeds up the reconstruction by reducing the 2-D Fourier series and improves the precision.

Key words: Computerized Tomography scanning, frequency spectrum analysis, image reconstruction, projection vector, Fourier series