A Beam-Hardening Correction Method Based on Poly-Energetic Statistics in X-Ray CT
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摘要: 在X射线层析成像(X-CT)系统中,传统的CT重建算法都基于射线源是单能的假设提出的,而实际的射线源是多能的,直接由多能投影数据用传统的重建算法重建图像,会导致硬化效应。本文把实际的多能谱细化成若干个子能谱,根据光子数服从Poisson分布这一规律建立数学模型,在传统迭代重建算法的基础上,借用统计的方法进行参数估计。实验结果表明该方法可以有效消除重建图像中的杯状伪影,提高重建图像质量。Abstract: In X-ray computed tomography,traditional reconstruction algorithm is based on the hypothesis that X-ray source is monochromatic.However,the actual X-ray source is polychromatic.So reconstructing image from polychromatic projections with traditional reconstruction algorithm can cause beam-hardening artifacts.This article separated the polychromatic energy spectrum into several sub-energy spectrum.And build the math model according to the regularity that the number of detected photons is in conformity to Poisson distribution.Then make parameter estimation with the statistical method on the basis of traditional reconstruction algorithm.Experimental result indicates that such method can remove the cupping artifact in reconstructed image effectively and improve the reconstructed image quality.
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