Low-dose x-ray phase-contrast and absorption CT using equally sloped tomography
Low-dose x-ray phase-contrast and absorption CT using equally sloped tomography
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DOI：
10.1088/0031-9155/55/18/008
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发表时间：
2010-09-21
影响因子：
3.5
通讯作者：
Miao, Jianwei
中科院分区：
文献类型：
--
作者：
Fahimian, Benjamin P.;Mao, Yu;Miao, Jianwei
由于低剂量断层扫描和快速采集成像的目的，在传输CT模式中，通常需要从欠采样和噪声投影中进行断层扫描重建。然而，在这种情况下，由于违反奈奎斯特采样标准和噪声的存在，可能无法以可接受的精度重建。最近在透射电子断层扫描和相干衍射显微镜中的实验表明，等倾斜断层扫描技术（EST）是一种利用过采样迭代傅立叶重建的精确断层扫描方法，当投影数量明显不足时，相对于滤波后的投影和代数迭代方法，可以提供更准确的图像重建。在这里，我们通过开发新的重建算法来扩展这项技术，该算法允许以与实验预测一致的方式合并高级数学正则化约束，例如非局部平均总变分模型。然后，我们通过在欧洲同步辐射设施使用x射线吸收和相位对比CT模式对图像质量幻象进行模拟和实验，评估所开发算法的图像质量。我们的仿真和实验结果都表明，该方法可以在平行光束模式下减少60-75%的投影数量，同时获得与传统重建相当或更好的图像质量。随着大规模、紧凑型同步辐射设备在世界范围内的快速发展，低剂量x射线吸收和相衬CT的实施可以利用这些先进的x射线源在生物学和医学上找到广泛的应用。
Tomographic reconstruction from undersampled and noisy projections is often desirable in transmission CT modalities for purposes of low-dose tomography and fast acquisition imaging. However under such conditions, due to the violation of the Nyquist sampling criteria and the presence of noise, reconstructions with acceptable accuracy may not be possible. Recent experiments in transmission electron tomography and coherent diffraction microscopy have shown that the technique of equally sloped tomography (EST), an exact tomographic method utilizing an oversampling iterative Fourier-based reconstruction, provides more accurate image reconstructions when the number of projections is significantly undersampled relative to filtered back projection and algebraic iterative methods. Here we extend this technique by developing new reconstruction algorithms which allow for the incorporation of advanced mathematical regularization constraints, such as the nonlocal means total variational model, in a manner that is consistent with experimental projections. We then evaluate the resulting image quality of the developed algorithm through simulations and experiments at the European Synchrotron Radiation Facility on image quality phantoms using the x-ray absorption and phase contrast CT modalities. Both our simulation and experimental results have indicated that the method can reduce the number of projections by 60-75% in parallel beam modalities, while achieving comparable or better image quality than the conventional reconstructions. As large-scale and compact synchrotron radiation facilities are currently under rapid development worldwide, the implementation of low-dose x-ray absorption and phase-contrast CT can find broad applications in biology and medicine using these advanced x-ray sources.