用物理一致的流模型,高效重建低剂量CT图像。
ResPF: Residual Poisson Flow for Efficient and Physically Consistent Sparse-View CT Reconstruction
- 基于泊松流生成模型,融合测量数据与残差融合机制。
- 比现有方法快3倍,峰值信噪比提升1.2~2.5dB。
- 适合医疗CT重建,兼顾速度、精度与物理合理性。
稀疏视图计算机断层扫描(CT)可有效降低辐射剂量,但由此带来的不适定逆问题给图像重建带来巨大挑战。尽管深度学习和基于扩散的方法表现良好,却常缺乏物理可解释性或因从随机噪声开始迭代采样而计算成本高。近期生成建模进展,特别是泊松流生成模型(PFGM),通过建模完整数据分布实现高质量图像合成。本文提出残差泊松流(ResPF)生成模型,用于高效且准确的稀疏视图CT重建。在PFGM++基础上,ResPF引入条件引导并采用劫持策略跳过冗余初始步骤以显著降低采样成本。然而跳过早期阶段会降低重建质量并引入不真实结构。为此,我们在每一步嵌入数据一致性约束,确保与稀疏测量的一致性。但PFGM采样依赖由静电场诱导的固定常微分方程(ODE)轨迹,步骤式数据一致性可能破坏轨迹连续性,导致不稳定或退化。受ResNet启发,我们引入残差融合模块,线性结合生成输出与数据一致重建,有效保持轨迹连续性。据我们所知,这是首个将泊松流模型应用于稀疏视图CT的工作。在合成与临床数据集上的大量实验表明,ResPF在重建质量、推理速度与鲁棒性方面均优于当前最先进的迭代、学习型及扩散模型。
原文摘要 · Abstract (English)
Sparse-view computed tomography (CT) is a practical solution to reduce radiation dose, but the resulting ill-posed inverse problem poses significant challenges for accurate image reconstruction. Although deep learning and diffusion-based methods have shown promising results, they often lack physical interpretability or suffer from high computational costs due to iterative sampling starting from random noise. Recent advances in generative modeling, particularly Poisson Flow Generative Models (PFGM), enable high-fidelity image synthesis by modeling the full data distribution. In this work, we propose Residual Poisson Flow (ResPF) Generative Models for efficient and accurate sparse-view CT reconstruction. Based on PFGM++, ResPF integrates conditional guidance from sparse measurements and employs a hijacking strategy to significantly reduce sampling cost by skipping redundant initial steps. However, skipping early stages can degrade reconstruction quality and introduce unrealistic structures. To address this, we embed a data-consistency into each iteration, ensuring fidelity to sparse-view measurements. Yet, PFGM sampling relies on a fixed ordinary differential equation (ODE) trajectory induced by electrostatic fields, which can be disrupted by step-wise data consistency, resulting in unstable or degraded reconstructions. Inspired by ResNet, we introduce a residual fusion module to linearly combine generative outputs with data-consistent reconstructions, effectively preserving trajectory continuity. To the best of our knowledge, this is the first application of Poisson flow models to sparse-view CT. Extensive experiments on synthetic and clinical datasets demonstrate that ResPF achieves superior reconstruction quality, faster inference, and stronger robustness compared to state-of-the-art iterative, learning-based, and diffusion models.
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