本文選題：分能段CT成像 + 灰度階躍��； 參考：《中北大學(xué)》2017年碩士論文

【摘要】：X射線CT成像技術(shù)是應(yīng)用于工業(yè)無損檢測、公共安全檢查及醫(yī)療診斷等領(lǐng)域的重要手段之一,然而隨著科學(xué)技術(shù)的快速發(fā)展,適用于結(jié)構(gòu)分析的傳統(tǒng)單能CT成像技術(shù)已不能滿足目前工業(yè)CT對物質(zhì)對比度的高要求。這是由于在X射線成像系統(tǒng)中,實(shí)際X射線源發(fā)射的射線是由不同能譜信息組成的連續(xù)能譜,而該X射線對被檢測物體進(jìn)行透照以后,因?yàn)椴煌镔|(zhì)具有特殊的特征吸收,所以對X射線的衰減能力也不盡相同。但是常規(guī)的重建算法都是基于近似單能能譜的假設(shè)下,對采樣投影數(shù)據(jù)進(jìn)行重建,這種實(shí)際數(shù)據(jù)與仿真數(shù)據(jù)的不一致性,易導(dǎo)致重建圖像出現(xiàn)硬化偽影和金屬偽影,降低CT重建質(zhì)量。為此,國內(nèi)外研究人員針對雙能CT系統(tǒng)和光子計(jì)數(shù)探測器進(jìn)行了多能CT重建研究,但都由于成本較高,不易推廣應(yīng)用于實(shí)際工程中。鑒于雙能CT系統(tǒng)的成像基本數(shù)理原理,為了在原有的傳統(tǒng)CT系統(tǒng)的基礎(chǔ)上,實(shí)現(xiàn)多能CT成像的目的,本文研究了一種分能段CT的成像方法。論文基于仿真設(shè)計(jì)思想,建立了雙能段和多能段的分能段CT模型,通過仿真實(shí)驗(yàn)對分能段投影數(shù)據(jù)的特征分析以及對其重建圖像的對比度的研究,驗(yàn)證了模型的有效性和分能段CT成像理論與方法的意義。然后針對分能段投影的灰度階躍,采用精確高頻定位的小波分析理論,結(jié)合小波低頻的灰階修正小波系數(shù),實(shí)現(xiàn)了小波逆變換后投影的灰階修正,并通過仿真實(shí)驗(yàn)驗(yàn)證了該方法的可行性。為了從重建算法上,改進(jìn)分能段CT成像理論,實(shí)現(xiàn)多能段CT成像。最后基于E-ART雙能譜CT重建算法,提出了一種分能段CT掃描的多能迭代重建算法,通過仿真實(shí)驗(yàn)表明,分能段CT成像不僅能夠消除重建圖像偽影,而且實(shí)現(xiàn)圖像內(nèi)部物質(zhì)的區(qū)分,重建出高質(zhì)量的圖像。
[Abstract]:X-ray CT imaging is one of the most important methods used in industrial nondestructive testing, public safety inspection and medical diagnosis. However, with the rapid development of science and technology,The traditional single-energy CT imaging technique, which is suitable for structural analysis, can no longer meet the high requirement of material contrast in industrial CT.This is because, in an X-ray imaging system, the actual X-ray source is a continuous energy spectrum consisting of different energy spectrum information, and after the X ray is taken into account of the object being examined, because different substances have special characteristics of absorption,So the attenuation ability of X-ray is different.However, the conventional reconstruction algorithms are based on the assumption of approximate single energy spectrum to reconstruct the sampled projection data. This kind of actual data is inconsistent with the simulation data, which can easily lead to the appearance of hardened artifacts and metal artifacts in the reconstructed images.The quality of CT reconstruction was reduced.For this reason, researchers at home and abroad have carried out multi-energy CT reconstruction research on dual-energy CT system and photon counting detector, but because of the high cost, it is difficult to be popularized in practical engineering.In view of the basic mathematical principle of imaging of dual-energy CT system, in order to realize the purpose of multi-energy CT imaging on the basis of the original traditional CT system, this paper studies a kind of imaging method of segmented CT.Based on the idea of simulation design, the CT model of dual-energy segment and multi-energy segment is established, and the feature analysis of the projection data and the contrast of the reconstructed image are studied by simulation experiment.The validity of the model and the significance of the theory and method of segmental CT imaging are verified.Then, aiming at the grayscale step of the energy division projection, the wavelet analysis theory of accurate high frequency location is adopted, and the gray scale correction coefficient of wavelet low frequency is combined to realize the gray scale correction after inverse wavelet transform.The feasibility of the method is verified by simulation experiments.In order to improve the theory of split-segment CT imaging from the reconstruction algorithm, multilevel CT imaging can be realized.Finally, based on the E-ART dual energy spectrum CT reconstruction algorithm, a multi-energy iterative reconstruction algorithm is proposed. The simulation results show that the sub-energy segment CT imaging can not only eliminate the reconstructed image artifacts, but also realize the internal material differentiation.Reconstruct high quality images.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP391.41

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 項(xiàng)里偉;;雙能CT的研究現(xiàn)狀與發(fā)展趨勢[J];科技廣場;2016年09期

2 孫春霞;潘晉孝;陳平;;基于小波分析的分能段計(jì)算機(jī)斷層掃描成像[J];激光與光電子學(xué)進(jìn)展;2016年09期

3 牛素捚;潘晉孝;陳平;;基于能譜濾波分離的多譜計(jì)算機(jī)層析成像方法[J];光學(xué)學(xué)報(bào);2014年10期

4 張唯唯;張華;;雙能成像技術(shù)的最新進(jìn)展[J];中國醫(yī)療設(shè)備;2012年09期

5 唐智偉;胡廣書;;Dual Energy CT Imaging in Cone-Beam Micro-CT for Improved Attenuation Coefficient Measurement[J];Tsinghua Science and Technology;2011年04期

6 韋哲;鄭蕾;李戰(zhàn)明;;小波多分辨率理論在心音信號分析中的應(yīng)用[J];醫(yī)療衛(wèi)生裝備;2010年10期

7 喬志偉;魏學(xué)業(yè);韓焱;;濾波反投影算法的數(shù)值實(shí)現(xiàn)問題研究[J];機(jī)械管理開發(fā);2009年02期

8 王革;俞恒永;勃魯努·德·曼;莊天戈;趙俊;;X線CT研究與發(fā)展之展望[J];中國醫(yī)療器械雜志;2008年03期

9 董寶玉;;圓軌道XCT圖像重建的EM算法研究與實(shí)現(xiàn)[J];科技信息(學(xué)術(shù)研究);2007年17期

10 吳朝霞,劉力,柴新禹;可變約束OS-EM圖像重建算法仿真研究[J];中國生物醫(yī)學(xué)工程學(xué)報(bào);2004年01期

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