衍射增强成像是一种功能强大的相位衬度成像技术，其信息分离研究一直都是研究热点。提出了一种简便的信息分离方法——余弦曲线拟合法(Cosine Fitting Radiography, CFR)，该方法具有简便、样品所受辐射剂量低等优点。利用同步辐射实验和蒙特卡罗仿真方法，从角度信号成像模型出发解释了此方法，同时从噪声传递角度分析了该方法的性能和给出定量的评价指标，建立了衍射增强成像和光栅微分干涉成像之间更直观的联系。对理解衍射增强成像系统的噪声行为和提高信噪比具有一定的参考意义。%Background: Diffraction enhanced imaging (DEI) is a powerful phase contrast imaging technique. Purpose: This study aims to investigate the noise properties of a new simple cosine fitting radiography for DEI based on the angular signal response imaging prototype. Methods: The rocking curve can be treated as a angular signal response and a simple multi-information retrieval algorithm based on the cosine function fitting. A comprehensive analysis of noise properties in DEI, based on a noise model including the fluctuation of the photon source, and a bias of the analyzer crystal are also given. The validations have been performed with Monte Carlo simulations based on the Geant4 toolkit combined with the refractive process of X-ray and synchrotron radiation experimental data. Results: The cosine fitting radiography (CFR) has been verified by Monte Carlo simulations and experimental data which are in good agreement with each other. The noise penalty is drastically reduced with high photon flux, high visibility and high angular precision. Conclusions: Based on the angular signal response function prototype, we analyze and calculate the noise properties of DEI. In addition, the analytical method can build a strong connection between DEI and grating-based phase contrast imaging (GDPCI) and widely suitable for all kinds of measurement noises in angular signal response imaging prototype. The analysis is useful to understand the noise characteristics of DEI images and improve the signal-noise-ratio of the extracted information for biomedical imaging and material science.
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