ReCo-Diff: Residual-Conditioned Deterministic Sampling for Cold Diffusion in Sparse-View CT

TL;DR

ReCo-Diff introduces a residual-conditioned diffusion method for sparse-view CT that improves reconstruction accuracy and stability by leveraging observation residuals in a deterministic sampling process.

Contribution

It proposes a novel residual-conditioned diffusion framework that enhances sparse-view CT reconstruction without heuristic interventions.

Findings

Outperforms existing cold diffusion baselines in accuracy

Demonstrates improved stability and robustness under severe sparsity

Achieves measurement-aware correction during sampling

Abstract

Cold and generalized diffusion models have recently shown strong potential for sparse-view CT reconstruction by explicitly modeling deterministic degradation processes. However, existing sampling strategies often rely on ad hoc sampling controls or fixed schedules, which remain sensitive to error accumulation and sampling instability. We propose ReCo-Diff, a residual-conditioned diffusion framework that leverages observation residuals through residual-conditioned self-guided sampling. At each sampling step, ReCo-Diff first produces a null (unconditioned) baseline reconstruction and then conditions subsequent predictions on the observation residual between the predicted image and the measured sparse-view input. This residual-driven guidance provides continuous, measurement-aware correction while preserving a deterministic sampling schedule, without requiring heuristic interventions. Experimental results demonstrate that ReCo-Diff consistently outperforms existing cold diffusion sampling baselines, achieving higher reconstruction accuracy, improved stability, and enhanced robustness under severe sparsity.