无需配对数据,通过正弦图抖动实现低剂量CT去噪。
Zero-Shot Low-dose CT Denoising via Sinogram Flicking
- 利用正弦图中互补射线随机交换生成多组含噪图像。
- 在模拟数据上优于ZS-N2N等现有方法,保持图像分辨率。
- 适合临床无配对数据场景,尤其适用于低剂量CT重建。
许多低剂量CT成像方法依赖于监督学习,需要大量配对的噪声与干净图像。然而,临床实践中获取配对图像十分困难。为解决此问题,零样本自监督方法如ZS-N2N仅使用单张图像内部信息训练去噪网络,但常采用下采样操作导致图像分辨率下降,且训练数据受限于单一图像本身。本文提出基于正弦图抖动的零样本低剂量CT成像方法,在不依赖配对数据的前提下,通过随机互换正弦图中互补射线段,生成大量内容一致但噪声模式不同的正弦图副本。当动态显示时,这些正弦图因结构相同而噪声各异,呈现出闪烁效果,故称‘正弦图抖动’。我们采用轻量级模型(源自ZS-NSN)在这些正弦图对上进行训练,重复该过程以获得最终结果。模拟实验表明,该方法性能优于ZS-N2N等先进方法。
原文摘要 · Abstract (English)
Many low-dose CT imaging methods rely on supervised learning, which requires a large number of paired noisy and clean images. However, obtaining paired images in clinical practice is challenging. To address this issue, zero-shot self-supervised methods train denoising networks using only the information within a single image, such as ZS-N2N. However, these methods often employ downsampling operations that degrade image resolution. Additionally, the training dataset is inherently constrained to the image itself. In this paper, we propose a zero-shot low-dose CT imaging method based on sinogram flicking, which operates within a single image but generates many copies via random conjugate ray matching. Specifically, two conjugate X-ray pencil beams measure the same path; their expected values should be identical, while their noise levels vary during measurements. By randomly swapping portions of the conjugate X-rays in the sinogram domain, we generate a large set of sinograms with consistent content but varying noise patterns. When displayed dynamically, these sinograms exhibit a flickering effect due to their identical structural content but differing noise patterns-hence the term sinogram flicking. We train the network on pairs of sinograms with the same content but different noise distributions using a lightweight model adapted from ZS-NSN. This process is repeated to obtain the final results. A simulation study demonstrates that our method outperforms state-of-the-art approaches such as ZS-N2N.
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