Sunaguchi Naoki, Yuasa Tetsuya, Shimao Daisuke, Huang Zhuoran, Ichihara Shu, Nishimura Rieko, Iwakoshi Akari, Kim Jong-Ki, Gupta Rajiv, Ando Masami
Department of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 461-8673, Japan.
Graduate School of Engineering and Science, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan.
Int J Comput Assist Radiol Surg. 2025 Apr;20(4):653-663. doi: 10.1007/s11548-024-03303-y. Epub 2024 Dec 26.
In this paper, we describe an algebraic reconstruction algorithm with a total variation regularization (ART + TV) based on the Superimposed Wavefront Imaging of Diffraction-enhanced X-rays (SWIDeX) method to effectively reduce the number of projections required for differential phase-contrast CT reconstruction.
SWIDeX is a technique that uses a Laue-case Si analyzer with closely spaced scintillator to generate second derivative phase-contrast images with high contrast of a subject. When the projections obtained by this technique are reconstructed, a Laplacian phase-contrast tomographic image with higher sparsity than the original physical distribution of the subject can be obtained. In the proposed method, the Laplacian image is first obtained by applying ART + TV, which is expected to reduce the projection with higher sparsity, to the projection obtained from SWIDeX with a limited number of views. Then, by solving Poisson's equation for the Laplacian image, a tomographic image representing the refractive index distribution is obtained.
Simulations and actual X-ray experiments were conducted to demonstrate the effectiveness of the proposed method in projection reduction. In the simulation, image quality was maintained even when the number of projections was reduced to about 1/10 of the originally required views, and in the actual experiment, biological tissue structure was maintained even when the number of projections was reduced to about 1/30.
SWIDeX can visualize the internal structures of biological tissues with very high contrast, and the proposed method will be useful for CT reconstruction from large projection data with a wide field of view and high spatial resolution.
在本文中，我们描述了一种基于衍射增强X射线叠加波前成像（SWIDeX）方法的具有总变差正则化的代数重建算法（ART + TV），以有效减少差分相衬CT重建所需的投影数量。
SWIDeX是一种使用带有紧密间隔闪烁体的劳厄型硅分析仪来生成具有高对比度的被检体二阶导数相衬图像的技术。当对通过该技术获得的投影进行重建时，可以获得比被检体原始物理分布具有更高稀疏性的拉普拉斯相衬断层图像。在所提出的方法中，首先通过将预期能减少具有更高稀疏性投影的ART + TV应用于从SWIDeX获得的有限视角投影来获得拉普拉斯图像。然后，通过求解拉普拉斯图像的泊松方程，获得表示折射率分布的断层图像。
进行了模拟和实际X射线实验以证明所提出方法在减少投影方面的有效性。在模拟中，即使投影数量减少到原本所需视角的约1/10，图像质量仍得以保持；在实际实验中，即使投影数量减少到约1/30，生物组织结构仍得以保持。
SWIDeX能够以非常高的对比度可视化生物组织的内部结构，并且所提出的方法对于从具有宽视野和高空间分辨率的大量投影数据进行CT重建将是有用的。
