基于噪声功率谱的CT图像噪声评价

目的 设计并探讨基于噪声功率谱（NPS）的CT图像噪声评价方法。方法 改变CT图像扫描参数以及重建参数获取图像，采用NPS与传统标准差（SD）两种方法对该图像进行噪声检测，并对比两种检测结果。结果 NPS曲线幅值与层厚和剂量成反比，与重建算法的增强程度成正比。重建算法、层厚和剂量对噪声指数的影响能够在NPS曲线上得到明显的体现。结论 NPS能够从幅值与频率方面反应噪声变化，与SD方法相结合可形成更为完善的噪声评价体系。

Noise power spectrum-based evaluation of CT image noise

Objective To design and discuss the method for evaluating CT image noise based on noise power spectrum (NPS). Methods CT images were acquired with different parameters. The NPS and standard deviation (SD) were computed for evaluating the image noise, and then two results were compared. Results NPS peak value was negatively related with slice and dose, and positively related with reconstruction algorithm. The factors variation, such as reconstruction algorithm, slice and dose, which can influence the CT image noise level, was reflected in the NPS curves obviously. Conclusion The NPS can reflect the magnitude and frequency content of the noise variations. It will build a relatively perfect evaluation method for noise evaluating system by combining NPS with SD.