Piecewise Structural Diffusion Defined on Shape Index for Noise Reduction in Dual-Energy CT Images
The increasing radiation dose in dual-energy CT (DE-CT) scanning due to the double exposures at 80 kVp and 140 kVp is a major concern in the application of DE-CT. This paper presents a novel image-space denoising method, called piecewise structural diffusion (PSD), for the reduction of noise in low-dose DE-CT images. Three principle structures (plate, ridge, and cap) and their corresponding diffusion tensors are formulated based on the eigenvalues of a Hessian matrix. The local diffusion tensor that is piecewise-defined on the domain of shape index is composed by a linear combination of two diffusion tensors of the associated principle structures. A single diffusion tensor calculated from the fused DE-CT image is applied to both high- and low-energy images. In the DE-CT colon phantom study, we demonstrated that DE-CT images filtered by PSD yielded the similar image quality with half of radiation doses.
KeywordsNoise reduction dual-energy CT dual-energy CT colonography
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