影响CT图像质量的因素包括空间分辨率、密度分辨率、噪声、层厚、伪影、窗宽和窗位以及照相机曝光参数 -胶片 -冲洗体系等。其中CT噪声是评价其成像质量的重要指标之一 ,噪声水平是与成像质量密切相关的性能参数 ,它直接影响和限制着系统的低对比度空间分辨率[1,2 ] 。而扫描层 Factors affecting CT image quality include spatial resolution, density resolution, noise, layer thickness, artifacts, window width and window level, and camera exposure parameters - film-wash system. Among them, CT noise is one of the important indexes to evaluate the imaging quality. The noise level is a performance parameter closely related to the imaging quality, which directly affects and limits the low spatial resolution of the system [1,2]. While scanning layer