Dual-dictionary learning-based iterative image reconstruction for spectral computed tomography application.
Dual-dictionary learning-based iterative image reconstruction for spectral computed tomography application.
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DOI：
10.1088/0031-9155/57/24/8217
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发表时间：
2012-12-21
影响因子：
3.5
通讯作者：
Molloi S
中科院分区：
文献类型：
--
作者：
Zhao B;Ding H;Lu Y;Wang G;Zhao J;Molloi S
在本研究中，我们研究了一种新的迭代重建（IR）方法与双字典学习（Dual-Dictionary Learning，DAI）结合在基于碲锌镉（CZT）光子计数探测器的专用乳腺计算机断层扫描（CT）系统中进行图像重建的有效性，并将其与滤波反投影（FBP）进行了比较。该方法的最终目标是在不牺牲图像质量的情况下减少重建所需的投影数量。在扇形束CT系统中扫描死后乳房样本，并使用IR和FBP方法从100-600个投影重建。计算乳腺腺体和脂肪组织的对比噪声比（CNR），比较从红外和FBP重建图像的质量。使用直径为643、813、1020、1290和1630 µm的铝（Al）丝在直径为13 cm的塑料环氧树脂体模中评价两种重建技术的空间分辨率。对于相同数量的投影重建的图像，IR与FBP相比，空间分辨率和CNR都有所提高。与FBP重建相比，在保持相同的空间分辨率的情况下，通过使用投影少6倍的IR方法，CNR从3.4提高到7.5。该研究表明，与FBP方法相比，IR方法结合ESTA可以显着减少CT重建所需的投影数量，同时实现更好的CNR并保持相同的空间分辨率。由此，通过在基于CZT的乳房CT系统中使用这种用于图像重建的IR方法，辐射剂量和扫描时间可以潜在地减少大约6倍。
In this study, we investigated the effectiveness of a novel Iterative Reconstruction (IR) method coupled with Dual-Dictionary Learning (DDL) for image reconstruction in a dedicated breast Computed Tomography (CT) system based on a Cadmium-Zinc-Telluride (CZT) photon-counting detector and compared it to the Filtered-Back-Projection (FBP) method with the ultimate goal of reducing the number of projections necessary for reconstruction without sacrificing image quality. Postmortem breast samples were scanned in a fan-beam CT system and were reconstructed from 100–600 projections with both IR and FBP methods. The Contrast-to-Noise Ratio (CNR) between the glandular and adipose tissues of the postmortem breast samples was calculated to compare the quality of images reconstructed from IR and FBP. The spatial resolution of the two reconstruction techniques was evaluated using Aluminum (Al) wires with diameters of 643, 813, 1020, 1290 and 1630 µm in a plastic epoxy resin phantom with diameter of 13 cm. Both the spatial resolution and the CNR were improved with IR compared to FBP for the images reconstructed from the same number of projections. In comparison with FBP reconstruction, the CNR was improved from 3.4 to 7.5 by using the IR method with 6-fold fewer projections while maintaining the same spatial resolution. The study demonstrated that the IR method coupled with DDL could significantly reduce the required number of projections for a CT reconstruction compared to FBP method while achieving a much better CNR and maintaining the same spatial resolution. From this, the radiation dose and scanning time can potentially be reduced by a factor of approximately 6 by using this IR method for image reconstruction in a CZT-based breast CT system.