ISSN 1004-4140
    CN 11-3017/P

    基于对极几何一致性的经验多项式CBCT射束硬化校正方法

    Empirical Polynomial Beam Hardening Correction for Cone-Beam Computed Tomography Based on Epipolar Consistency

    • 摘要: 针对多材料物体锥束CT成像中射束硬化导致图像质量降低的问题,本文提出一种基于对极几何一致性的经验多项式CBCT射束硬化校正方法。首先将多项式校正模型中的多色投影表示为水投影与骨投影,利用水校正方法获取水投影,并对水投影进行图像重建、分割和正投影,以获取骨组织路径长度表征骨投影,进而构建出基于水校正投影和骨组织路径长度的经验多项式校正模型;然后结合对极几何一致性条件与经验多项式校正模型,构建带等式约束的最小二乘问题;最后采用拉格朗日乘数法求解该问题,得到最优多项式校正系数,实现射束硬化校正。实验结果表明该方法可有效抑制CT重建图像中的杯状伪影与条纹伪影,提高图像质量。

       

      Abstract: To address image quality degradation caused by beam hardening in cone-beam computed tomography (CBCT) of multi-material objects, this study proposes an empirical polynomial-based beam-hardening correction method based on epipolar consistency conditions. First, the polychromatic projection in the polynomial correction model is represented as a combination of water and bone projections. The water projection is acquired through a water correction method, and then subjected to image reconstruction, segmentation, and forward projection to obtain the bone tissue path length to characterize the bone projection. Consequently, an empirical polynomial correction model is constructed based on the water-corrected projection and bone tissue path length. Subsequently, by combining epipolar consistency conditions with the empirical polynomial correction model, an equality-constrained least-squares problem is formulated. Finally, the Lagrange multiplier method is employed to solve this problem, yielding optimal polynomial correction coefficients to achieve beam-hardening correction. Experimental results demonstrated that the proposed method could effectively suppress cupping and streak artifacts in reconstructed CT images, thereby improving overall image quality.

       

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