单视角CT非线性图像重建不确定度量化研究

Research on uncertainty quantification of single-view CT nonlinear image reconstruction

  • 摘要: 闪光照相技术可以对快速物理过程进行诊断,但由于是瞬时照相,获得的投影数量稀少。考虑视角典型受限(即一个视角)的情况下,CT图像重建不确定度量化方法的研究。目前的单视角CT图像重建不确定度量化方法通常假设在线性光程方程中含有高斯噪声的模型,但这种物理模型过于简化。从朗博比尔定律(Lambert-Beer’s law)出发,构建了关于透射率的指数衰减方程及其高斯噪声项,得到更合理的非线性图像重建模型,推导得到相应的非线性后验概率密度函数,然后利用RTO算法以及Gibbs算法对该后验概率进行抽样,通过统计抽样样本得到图像重建的平均值及其不确定度。为了验证新方法的有效性,给出了模拟数据,并与基于光程方程的线性图像重建结果进行了对比,结果表明基于透射率方程的非线性图像重建方法具有更好的不确定度估计潜力。

     

    Abstract: Flash radiography enables the diagnosis of rapid physical processes, yet the instantaneous nature of image acquisition results in a severely limited number of projections. This study investigates uncertainty quantification methods for computed tomography (CT) image reconstruction under the typical scenario of a single projection view. Current approaches for single-view CT uncertainty quantification often adopt oversimplified physical models, assuming linearized optical path equations with Gaussian noise. To address this limitation, we derive a more realistic nonlinear reconstruction framework based on the Lambert-Beer’s law, constructing an exponential attenuation model for transmittance with an integrated Gaussian noise term. This formulation yields a nonlinear posterior probability density function, which is subsequently sampled using the Randomize-Then-Optimize (RTO) algorithm combined with Gibbs sampling. The reconstructed image and its associated uncertainty are obtained through statistical analysis of the sampled data. Numerical simulations validate the proposed method, with comparative results against conventional linearized models demonstrating its superior potential for accurate uncertainty estimation in image reconstruction.

     

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