多模型迭代重建算法对CT图像质量影响的模型研究

Effect of Adaptive Statistic Iterative Reconstruction Veo on CT Image Quality:Phantom Study

目的通过模型研究,客观评价多模型迭代重建算法(ASi R-V)对CT图像质量的影响。材料与方法在不同条件下,分别扫描20 cm水模型和QA模型。以不同迭代权重,对原始数据进行重建。迭代比例选择从ASi R-V 0%即滤波反投影(FBP)到ASi R-V 100%,间隔10%。比较不同迭代水平图像的噪声、密度分辨率及空间分辨率。结果与FBP图像相比,随着ASi R-V比重增加,图像噪声水平明显下降,密度分辨率明显提高,而空间分辨率略有提高。在120 k V、200 m A扫描条件下,ASi R-V 50%、ASi R-V 100%较FBP分别降低标准差约32%、58%,提高低对比探测能力约12%、21%,提高调制传递函数50约2%、5%。结论基于模型的ASi R-V不仅可以显著降低噪声、明显提高密度分辨率,而且略提高空间分辨率。随着迭代比例增加,改善效果增加。

Purpose To evaluate the performance of a brand-new iterative reconstruction algorithm named adaptive statistic iterative reconstruction Veo（ASi R-V） based on objective methods.Material and Methods We performed scans on 20 cm radiation level using water and QA phantoms.Images were reconstructed using different ASi R-V blending percentages from ASi R-V 0%（filtered back projection,FBP） to ASi R-V 100%,at interval of 10%.Noise standard deviation（SD） and density resolution（low-contrast detectability,LCD） were measured by scanning water phantom.Modulation transfer function（MTF） was measured by scanning QA phantom.We compared reconstructed images of noise SD,LCD and MTF by using different blending percentages of ASi R-V.Results As the increasing ASi R-V percentage,noise SD level significantly reduced and LCD significantly increased,while MTF slightly increased compared with FBP.Under the scan condition of 120 k V,200 m A,noise SD of ASi R-V 50% and ASi R-V 100% decreased by 32% and 58%,respectively;LCD increased by 12% and 21%,respectively;MTF increased by 2% and 5%,respectively compared with FBP.Conclusion Our study indicated ASi R-V provided a significant reduction of image noise,improvement of density resolution as well as a slight improvement of spatial resolution.Therefore,this new algorithm has the potential effect to reduce radiation dose without compromising image quality.