摘要：
多譜CT成像是通過(guò)不同譜段的CT圖像表征檢測(cè)對(duì)象中的不同組分.為了便于在同一視圖中顯示所有組分的信息,需要研究多譜CT序列的融合方法;但是常用融合方法如加權(quán)平均法、小波變換融合法等都是針對(duì)圖像細(xì)節(jié)信息的優(yōu)化,不能表達(dá)組分的物理特性,從而導(dǎo)致融合圖像的灰度不具有物理表征性,影響CT的定量檢測(cè).為此,結(jié)合具有物理表征特征的數(shù)據(jù)約束模型(DCM),開(kāi)展了基于先驗(yàn)組分的多譜CT序列DCM融合算法研究.首先通過(guò)能譜濾波分離的成像方法獲得多個(gè)能譜范圍內(nèi)的多能投影數(shù)據(jù),采用TV-OSEM算法重建不同能譜段的CT序列;其次,利用傳統(tǒng)DCM模型和改進(jìn)DCM模型分別對(duì)多譜CT序列進(jìn)行融合,傳統(tǒng)DCM模型是嚴(yán)格單能的,由于濾波后能譜的非嚴(yán)格單能特性,其融合結(jié)果不能表征出對(duì)象序列中的全部組分.針對(duì)此問(wèn)題提出了改進(jìn)DCM模型.改進(jìn)DCM模型選擇了新的體元定義,并且在多譜CT序列融合中引入先驗(yàn)組分作為參照,通過(guò)先驗(yàn)物質(zhì)對(duì)融合結(jié)果中其他物質(zhì)進(jìn)行校準(zhǔn),實(shí)現(xiàn)檢測(cè)對(duì)象中各組分位置的準(zhǔn)確分布.仿真實(shí)驗(yàn)表明,該方法可從物理表征正確性的角度,實(shí)現(xiàn)多譜CT序列融合,在滿足CT序列中不同組分區(qū)分的同時(shí),其融合圖像的灰度具有物理可參照性,有利于后續(xù)的CT定量檢測(cè).%Multi-spectral CT imaging is to characterize the different components in the CT images of different spectral ranges. For more convenient displaying all components physical information in an image,it is necessary to study the fusion method of multi-spectral CT sequence.But the commonly used fusion methods,such as weighted average method and wavelet transform fu-sion method,are mainly for the optimization of image information.The physical properties of the components can not be ex-pressed,so that the gray scale of the fused image without physical representation affects the quantitative detection of CT.A multi-spectral CT sequence DCM fusion algorithm based on priori components with physical characterization was presented. First,we got multi-spectrum projection sequence by Imaging method separated by energy spectrum filtering and the CT sequence with different energy spectrum can be obtained by TV-OSEM reconstruction algorithm.Second,the traditional DCM model and the improved DCM model were used to fuse the multi-spectral CT sequences.The traditional DCM model was strictly single en-ergy,considering the non-strict monocular characteristic of the filtered energy spectrum.The fusion result can not accurately characterized all the components in the object sequence.To solve this problem,an improved DCM model was proposed.In the improved DCM model,a new voxel definition was selected and a metallic priori component was introduced as a reference sub-stance in the multi-spectral CT sequence.The Prior component was used to calibrate other substances in the fusion results.Thus accurate distribution of each component in the CT sequence was achieved by calibration of the fusion results.Simulation result, the method can realize multi-spectral CT sequence fusion from the perspective of the physical representation.while satisfying the different components distinction of the CT sequence,the gray scale of its fused image had physical reference.This method is beneficial to the subsequent CT quantitative detection.
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