{"title":"A Parametric Physical Model-Based X-Ray Spectrum Estimation Approach for CT Imaging","authors":"Shaojie Chang;Chaoyang Zhang;Xuanqin Mou;Qiong Xu;Lijun He;Xi Chen","doi":"10.1109/TRPMS.2024.3374702","DOIUrl":null,"url":null,"abstract":"X-ray spectrum plays an essential role in CT applications. Since it is difficult to measure X-ray spectrum directly in practice, X-ray spectrum is always indirectly obtained by using transmission measurements through a calibration phantom of known thickness and materials. These methods are independent of CT image reconstruction and bring extra cost. To solve this problem, we propose a parametric physical model-based X-ray spectrum estimation algorithm for CT imaging. First, an X-ray spectrum model with six parameters is proposed, which is derived from the X-ray imaging physics. Second, a template image containing different material components can be obtained by segmenting CT reconstructed images with a simple method. And the estimated projections can be calculated by reprojecting the template image with the proposed spectrum model. Finally, the six model parameters can be solved by iteratively minimizing the error between the estimated projection and real measurements. The effectiveness of the proposed method has been validated on both simulated and real data. Experimental results demonstrate that the proposed method can estimate the accurate spectra at different energies and provide a good reconstruction of characteristic radiations without extra cost.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":null,"pages":null},"PeriodicalIF":4.6000,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Transactions on Radiation and Plasma Medical Sciences","FirstCategoryId":"1085","ListUrlMain":"https://ieeexplore.ieee.org/document/10462530/","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
引用次数: 0
Abstract
X-ray spectrum plays an essential role in CT applications. Since it is difficult to measure X-ray spectrum directly in practice, X-ray spectrum is always indirectly obtained by using transmission measurements through a calibration phantom of known thickness and materials. These methods are independent of CT image reconstruction and bring extra cost. To solve this problem, we propose a parametric physical model-based X-ray spectrum estimation algorithm for CT imaging. First, an X-ray spectrum model with six parameters is proposed, which is derived from the X-ray imaging physics. Second, a template image containing different material components can be obtained by segmenting CT reconstructed images with a simple method. And the estimated projections can be calculated by reprojecting the template image with the proposed spectrum model. Finally, the six model parameters can be solved by iteratively minimizing the error between the estimated projection and real measurements. The effectiveness of the proposed method has been validated on both simulated and real data. Experimental results demonstrate that the proposed method can estimate the accurate spectra at different energies and provide a good reconstruction of characteristic radiations without extra cost.
X 射线光谱在 CT 应用中起着至关重要的作用。由于在实践中很难直接测量 X 射线频谱,因此总是通过已知厚度和材料的校准模型进行透射测量,从而间接获得 X 射线频谱。这些方法与 CT 图像重建无关,而且会带来额外成本。为解决这一问题,我们提出了一种基于参数物理模型的 CT 成像 X 射线光谱估算算法。首先,我们从 X 射线成像物理学出发,提出了具有六个参数的 X 射线光谱模型。其次,可以通过简单的方法分割 CT 重建图像,获得包含不同材料成分的模板图像。然后,利用所提出的光谱模型对模板图像进行再投影,即可计算出估计投影。最后,通过迭代最小化估计投影与实际测量之间的误差,即可求解六个模型参数。建议方法的有效性已在模拟数据和真实数据上得到验证。实验结果表明,所提出的方法可以估算出不同能量下的精确光谱,并在不增加额外成本的情况下提供良好的特征辐射重建。