在分析不同能谱对应的公共能量段下多能投影之间关系的基础上,研究了基于减影融合的多谱CT成像算法。该方法在分析不同射线源参数下射线能谱之间关联性的基础上,建立了递变能量多能投影序列减影融合模型,并通过递变能量获取工件的多个多能投影序列,结合减影融合模型,对所得投影图像进行减影融合,去除公共能量段投影信息,获取近似窄能谱的投影信息。最后采用统计迭代算法进行图像重建,减小噪声干扰,提高重建质量。实验结果表明,所提方法能通过多谱投影减影融合得到近似窄谱投影,有效抑制射束硬化伪影。

Based on the analysis of the relationship between the photon intensity received by the detector under the common energy segment corresponding to different energy spectra, a multi-spectral computed tomography (CT) imaging method using subtraction fusion is proposed herein. From the analysis of the correlation across the X-ray spectrum using different X-ray source parameters, we establish a subtraction fusion model involving various energy polychromatic projection sequences and obtain multiple sequences of the phantom by varying energy. Combined with the subtraction fusion model, the projection is obtained at different energies, the projection information of the common energy segments is removed using subtraction fusion, and the projection information of the approximate narrow spectrum is derived. Finally, the expectation-maximization/total-variation algorithm is used to reconstruct the image, reduce the noise interference, and improve the reconstruction quality. Theoretical analysis and experiments show that the proposed method can obtain approximate narrow-spectrum projection through multi-spectral projection subtraction fusion, which can effectively suppress beam hardening artifacts and improve CT imaging quality.