硬X射线微分相衬成像的噪声特性分析

量子噪声引起光强随机波动是影响X射线相衬图像质量的一个重要因素.提出了一种针对硬X射线微分相衬成像噪声特性的分析方法,通过数值模拟获得了量子噪声对成像结果的作用规律.模拟结果表明,折射像和散射像的噪声均方差与叠栅条纹对比度成反比关系,叠栅条纹对比度越大,统计所得的均方差值越小.在保证X射线探测效率的前提下,提高叠栅条纹对比度将有利于获得高质量的相衬图像,并为有效减少X射线曝光剂量提供条件.

Noise analysis of hard X-ray differential phasecontrast imaging

Quantum noise is an important factor influencing the quality of the images obtained by X-ray phase contrast imaging because it induces a random fluctuation on the intensity. In this paper, a method is reported to analyze the noise characteristics of hard X-ray differential phase contrast imaging, and the relationship between the quantum noise and images is determined by numerical simulation. The results show that the mean square deviations of the refractive and scattering images are inversely proportional to the visibility of moiré fringe. That is to say, the higher visibility of moiré fringe leads to the lower mean square deviations of the refractive and scattering images. Therefore, in the case of ensuring an enough X-ray detection efficiency, the improvement in the visibility of moiré fringe will be beneficial to obtaining high-quality phase contrast images and the effective reduction of X-ray exposure dose.
Keywords： X-ray optics grating-based phase contrast imaging quantum noise visibility of moiré fringe