论文标题

使用深钢筋学习的低剂量X射线计算机断层扫描的有限参数denoising

Limited Parameter Denoising for Low-dose X-ray Computed Tomography Using Deep Reinforcement Learning

论文作者

Patwari, Mayank, Gutjahr, Ralf, Raupach, Rainer, Maier, Andreas

论文摘要

深度学习的使用成功解决了医学成像领域的几个问题。深度学习已成功地应用于CT降解问题。但是,深度学习的使用需要大量数据来训练深卷积网络(CNN)。此外,由于参数计数较大,这种深入的CNN可能会导致意外的结果。在这项研究中,我们介绍了一个新型的CT DeNoising框架,该框架具有可解释的行为,并提供有限的数据提供了有用的结果。我们在投影域和音量域中使用双边滤波来消除噪声。为了说明非平稳噪声,我们为每个投影视图和每个卷像素调整$σ$参数。调整由两个深CNN进行。由于标签的不切实际,这两个深CNN通过深Q强化学习任务进行了训练。该任务的奖励是通过使用由神经网络代表的自定义奖励功能生成的。我们的实验是针对Mayo Clinic TCIA数据集进行的腹部扫描和AAPM低剂量CT大挑战的。我们的Denoising框架具有出色的脱氧性能,将PSNR从28.53增加到28.93,并将SSIM从0.8952增加到0.9204。我们的表现要优于几个最先进的深CNN,它们的参数数量较高(p值(PSNR)= 0.000,p-value(ssim)= 0.000)。我们的方法不会引入任何模糊,这些模糊是由基于MSE损失的方法或任何深度学习工件引入的,这些方法是由基于WGAN的模型引入的。我们的消融研究表明,参数调整和使用我们的奖励网络会产生最佳结果。

The use of deep learning has successfully solved several problems in the field of medical imaging. Deep learning has been applied to the CT denoising problem successfully. However, the use of deep learning requires large amounts of data to train deep convolutional networks (CNNs). Moreover, due to large parameter count, such deep CNNs may cause unexpected results. In this study, we introduce a novel CT denoising framework, which has interpretable behaviour, and provides useful results with limited data. We employ bilateral filtering in both the projection and volume domains to remove noise. To account for non-stationary noise, we tune the $σ$ parameters of the volume for every projection view, and for every volume pixel. The tuning is carried out by two deep CNNs. Due to impracticality of labelling, the two deep CNNs are trained via a Deep-Q reinforcement learning task. The reward for the task is generated by using a custom reward function represented by a neural network. Our experiments were carried out on abdominal scans for the Mayo Clinic TCIA dataset, and the AAPM Low Dose CT Grand Challenge. Our denoising framework has excellent denoising performance increasing the PSNR from 28.53 to 28.93, and increasing the SSIM from 0.8952 to 0.9204. We outperform several state-of-the-art deep CNNs, which have several orders of magnitude higher number of parameters (p-value (PSNR) = 0.000, p-value (SSIM) = 0.000). Our method does not introduce any blurring, which is introduced by MSE loss based methods, or any deep learning artifacts, which are introduced by WGAN based models. Our ablation studies show that parameter tuning and using our reward network results in the best possible results.

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