Joint Estimation of Scatter Distribution and Material Maps in Volumetric Dual-Layer Cone-Beam CT

Dual-energy cone-beam CT (DE-CBCT) provides a flexible spectral imaging approach for volumetric material quantification, but its accuracy can be severely degraded by photon scatter. We propose a joint scatter estimation and one-step material decomposition framework for DE-CBCT using a dual-layer flat-panel detector. In this method, scatter is explicitly modeled in the physical forward model, while a diffusion model provides a sophisticated anatomical prior for material decomposition and also acts as a scatter-free prior for scatter estimation. The joint estimation framework operates iteratively, alternating between diffusion posterior sampling and prior-guided scatter estimation to jointly recover material density maps and scatter distributions. Experiments using an anthropomorphic head phantom show that direct material decomposition from cone-beam projections leads to significant bias and cross-talk between water and bone channels. In contrast, the proposed joint estimation strategy achieves accurate water-bone separation and substantially improves quantitative accuracy. The proposed method provides a promising framework for accurate spectral CBCT imaging.