Volume 36, Issue 12

Given the potential risk of X-ray radiation to the patient, low-dose CT has attracted a considerable interest in the medical imaging field. Currently, the main stream low-dose CT methods include vendor-specific sinogram domain filtration and iterative reconstruction algorithms, but they need to access raw data, whose formats are not transparent to most users. Due to the difficulty of modeling the statistical characteristics in the image domain, the existing methods for directly processing reconstructed images cannot eliminate image noise very well while keeping structural details. Inspired by the idea of deep learning, here we combine the autoencoder, deconvolution network, and shortcut connections into the residual encoder–decoder convolutional neural network (RED-CNN) for low-dose CT imaging. After patch-based training, the proposed RED-CNN achieves a competitive performance relative to the-state-of-art methods in both simulated and clinical cases. Especially, our method has been favorably evaluated in terms of noise suppression, structural preservation, and lesion detection.

鉴于X射线辐射对患者的潜在风险，低剂量CT在医学成像领域引起了相当大的关注。目前，主流的低剂量CT方法包括设备特定的正弦图域滤波和迭代重建算法，但它们需要访问原始数据，而这些数据的格式对大多数用户不透明。由于在图像域中建模统计特性的困难，现有直接处理重建图像的方法在保持结构细节的同时无法很好地消除图像噪声。受深度学习思想的启发，我们将自编码器、反卷积网络和快捷连接结合到残差编码器-解码器卷积神经网络（RED-CNN）中，用于低剂量CT成像。经过基于块的训练后，所提出的RED-CNN在模拟和临床案例中均达到了与最先进方法相竞争的性能。特别是，我们的方法在噪声抑制、结构保留和病变检测方面得到了良好的评价。

Noise is inherent to low-dose CT acquisition. We propose to train a convolutional neural network (CNN) jointly with an adversarial CNN to estimate routine-dose CT images from low-dose CT images and hence reduce noise. A generator CNN was trained to transform low-dose CT images into routine-dose CT images using voxelwise loss minimization. An adversarial discriminator CNN was simultaneously trained...

噪声是低剂量CT采集固有的。我们提出联合训练卷积神经网络（CNN）和对抗性CNN，从低剂量CT图像估计常规剂量CT图像，从而降低噪声。训练生成器CNN，通过体素级损失最小化将低剂量CT图像转换为常规剂量CT图像。同时训练对抗性判别器CNN...

Dose reduction in computed tomography (CT) is essential for decreasing radiation risk in clinical applications. Iterative reconstruction algorithms are one of the most promising way to compensate for the increased noise due to reduction of photon flux. Most iterative reconstruction algorithms incorporate manually designed prior functions of the reconstructed image to suppress noises while maintain...

在计算机断层扫描(CT)中减少剂量对于降低临床应用的辐射风险至关重要。迭代重建算法是补偿由于光子通量减少而增加的噪声的最有前途的方法之一。大多数迭代重建算法结合了手动设计的重建图像先验函数，以抑制噪声并保持图像质量。

In low dose computed tomography (LDCT) imaging, the data inconsistency of measured noisy projections can significantly deteriorate reconstruction images. To deal with this problem, we propose here a new sinogram restoration approach, the sinogram- discriminative feature representation (S-DFR) method. Different from other sinogram restoration methods, the proposed method works through a 3-D represe...

在低剂量计算机断层扫描(LDCT)成像中，测量噪声投影的数据不一致性会显著降低重建图像的质量。为了解决这一问题，我们提出了一种新的正弦图恢复方法，即正弦图判别性特征表示(S-DFR)方法。与其他正弦图恢复方法不同，该方法通过三维表示...

Computed tomography (CT) image recovery from low-mAs acquisitions without adequate treatment is always severely degraded due to a number of physical factors. In this paper, we formulate the low-dose CT sinogram preprocessing as a standard maximum a posteriori (MAP) estimation, which takes full consideration of the statistical properties of the two intrinsic noise sources in low-dose CT, i.e., the ...

未经过充分处理的低毫安秒采集的计算机断层扫描（CT）图像恢复总是由于多种物理因素而严重退化。本文将低剂量CT正弦图预处理公式化为标准最大后验（MAP）估计，充分考虑低剂量CT中两个内在噪声源的统计特性，即...

A single-scan dual-energy low-dose cone-beam CT (CBCT) imaging technique that exploits a multi-slit filter is proposed in this paper. The multi-slit filter installed between the x-ray source and the scanned object is reciprocated during a scan. The x-ray beams through the slits would generate relatively low-energy x-ray projection data, while the filtered beams would make high-energy projection da...

本文提出了一种利用多狭缝滤波器的单次扫描双能量低剂量锥束CT成像技术。在扫描过程中，安装在X射线源和扫描物体之间的多狭缝滤波器会往复运动。通过狭缝的X射线束会产生相对低能量的X射线投影数据，而经过滤波的射线束则会产生高能量的投影数据...

Despite the rapid developments of X-ray cone-beam CT (CBCT), image noise still remains a major issue for the low dose CBCT. To suppress the noise effectively while retain the structures well for low dose CBCT image, in this paper, a sparse constraint based on the 3-D dictionary is incorporated into a regularized iterative reconstruction framework, defining the 3-D dictionary learning (3-DDL) metho...

尽管X射线锥束CT（CBCT）发展迅速，但图像噪声仍然是低剂量CBCT的主要问题。为了有效抑制噪声同时保持低剂量CBCT图像的结构，本文将基于三维字典的稀疏约束引入正则化迭代重建框架，定义了三维字典学习（3-DDL）方法...

Dynamic cerebral perfusion computed tomography (DCPCT) has the ability to evaluate the hemodynamic information throughout the brain. However, due to multiple 3-D image volume acquisitions protocol, DCPCT scanning imposes high radiation dose on the patients with growing concerns. To address this issue, in this paper, based on the robust principal component analysis (RPCA, or equivalently the low-ra...

动态脑灌注计算机断层扫描（DCPCT）能够评估整个大脑的血流动力学信息。然而，由于需要多次三维图像体积采集协议，DCPCT扫描给患者带来高辐射剂量，这一问题日益受到关注。为了解决这一问题，本文基于鲁棒主成分分析（RPCA，或等价于低秩...

The valuable structure features in full-dose computed tomography (FdCT) scans can be exploited as prior knowledge for low-dose CT (LdCT) imaging. However, lacking the capability to represent local characteristics of interested structures of the LdCT image adaptively may result in poor preservation of details/textures in LdCT image. This paper aims to explore a novel prior knowledge retrieval and r...

全剂量计算机断层扫描（FdCT）扫描中的有价值结构特征可以作为低剂量CT（LdCT）成像的先验知识。然而，缺乏自适应地表示LdCT图像中感兴趣结构的局部特征的能力可能导致LdCT图像中细节/纹理的保留不佳。本文旨在探索一种新的先验知识检索和...

Cone-beam computed tomography (CBCT) has been widely used in radiation therapy. For accurate patient setup and treatment target localization, it is important to obtain high-quality reconstruction images. The total variation (TV) penalty has shown the state-of-the-art performance in suppressing noise and preserving edges for statistical iterative image reconstruction, but it sometimes leads to the ...

锥束计算机断层扫描（CBCT）已广泛应用于放射治疗。为了准确的病人定位和治疗靶区定位，获得高质量的重建图像至关重要。在统计迭代图像重建中，总变差（TV）罚分在抑制噪声和保持边缘方面表现出最先进的性能，但有时会导致...

This paper presents a joint optimization of dynamic fluence field modulation (FFM) and regularization in quadratic penalized-likelihood reconstruction that maximizes a task-based imaging performance metric. We adopted a task-driven imaging framework for prospective designs of the imaging parameters. A maxi-min objective function was adopted to maximize the minimum detectability index (d') througho...

本文提出了一种联合优化动态通量场调制（FFM）和二次惩罚似然重建中正则化的方法，该方法最大化基于任务的成像性能指标。我们采用了任务驱动的成像框架进行成像参数的前瞻性设计。采用极大极小目标函数，以最大化整个...的最小可检测指数（d'）。

In this paper, a newly developed statistical model-based image reconstruction [referred to as Simultaneous Multiple Artifacts Reduction in Tomographic RECONstruction (SMART-RECON)] is applied to low dose computer tomography (CT) myocardial perfusion imaging (CT-MPI). This method uses the nuclear norm of the spatial-temporal image matrix of the CT-MPI images as a regularizer, rather than a conventi...

本文介绍了一种新开发的基于统计模型的图像重建方法（称为同时多伪影减少断层重建，SMART-RECON），并将其应用于低剂量计算机断层扫描（CT）心肌灌注成像（CT-MPI）。该方法使用CT-MPI图像时空图像矩阵的核范数作为正则化项，而非传统方法...

Iodinated contrast-enhanced X-ray imaging of the breast has been studied with various modalities, including full-field digital mammography (FFDM), digital breast tomosynthesis (DBT), and dedicated breast CT. Contrast imaging with breast CT has a number of advantages over FFDM and DBT, including the lack of breast compression, and generation of fully isotropic 3-D reconstructions. Nonetheless, for ...

已经研究了使用各种模态的碘对比增强乳腺X射线成像，包括全视野数字乳腺摄影（FFDM）、数字乳腺断层合成（DBT）和专用乳腺CT。与FFDM和DBT相比，乳腺CT对比成像具有一些优势，包括无需乳腺压迫以及生成完全各向同性的三维重建。然而，为了...

Tomographic image reconstruction for low-dose computed tomography (CT) is increasingly challenging as dose continues to reduce in clinical applications. Pre-log domain methods and post-log domain methods have been proposed individually and each method has its own disadvantage. While having the potential to improve image quality for low-dose data by using an accurate imaging model, pre-log domain m...

低剂量计算机断层扫描（CT）的断层图像重建随着临床应用中剂量的持续降低而变得越来越具有挑战性。预对数域方法和后对数域方法已被分别提出，每种方法都有其自身的缺点。尽管通过使用精确的成像模型有可能改善低剂量数据的图像质量，但预对数域方法...

Repeated CT scans are known to increase the risk of cancer; thus, it is paradoxical to use multiple follow-up CT scans to monitor the development of a lung nodule and conduct early treatment of the nodule. In the case of a solitary lung nodule, regional scanning and region of interest (ROI) reconstruction are likely to restore the internal area at the nodule. A limited-range few-view CT is propose...

已知重复CT扫描会增加癌症风险；因此，使用多次随访CT扫描来监测肺结节的发展并对结节进行早期治疗是矛盾的。对于孤立性肺结节，区域扫描和感兴趣区域（ROI）重建可能恢复结节内部区域。提出了一种有限范围少视角CT...

This paper describes a new method for imageless needle and patient tracking in interventional CT procedures based on fractional CT scanning. Our method accurately locates a needle with a spherical marker attached to it at a known distance from the tip with respect to the patient in the CT scanner coordinate frame with online sparse scan sampling and without reconstructing the CT image. The key pri...

本文描述了一种基于分数CT扫描的介入CT手术中无图像针和患者追踪的新方法。我们的方法通过在线稀疏扫描采样，在不重建CT图像的情况下，在CT扫描仪坐标系中精确定位带有球形标记的针，该标记位于距离针尖已知距离处，并相对于患者定位。关键的前提...

We present a new method for on-line radiation dose optimization in repeat computer tomography (CT) scanning. Our method uses the information of the baseline scan during the repeat scanning to significantly reduce the radiation dose without compromising the repeat scan quality. It automatically registers the patient to the baseline scan using fractional scanning and detects in sinogram space the pa...

我们提出了一种在重复计算机断层扫描（CT）中在线辐射剂量优化的新方法。我们的方法在重复扫描期间利用基线扫描的信息，显著降低辐射剂量而不影响重复扫描质量。它通过分数扫描自动将患者配准到基线扫描，并在正弦图空间中检测...

The introduction of computed tomography (CT) in 1972 was among the most significant development in medical imaging since the discovery of X-rays in 1895. In addition, the innovation of computationally reconstructing tomographic images from projection data significantly influenced the development of other medical imaging modalities, such as magnetic resonance imaging and single photon and positron ...

1972年计算机断层扫描（CT）的引入是自1895年X射线发现以来医学成像领域最重要的进展之一。此外，从投影数据计算重建断层图像的创新显著影响了其他医学成像方式的发展，如磁共振成像、单光子发射和正电子发射断层成像...

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