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ID:32993834
大小:8.27 MB
页数:62页
时间:2019-02-18
《ct中金属伪影的校正分析》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、硕士学位论文投影得到相应的弦图;接着利用先验图像的前向投影进行归一化和线性插值,再乘以先验图像的投影进行反归一化;最后对校正投影进行FBP重建得到校正图像。实验表明,NMAR算法对金属植入物有较好的校正结果,即使对于邻近金属物体的高强度的伪影,也能消除大部分的伪影。在远离金属植入物的区域,经过NMAR算法校正后几乎不存在伪影。与单纯的线性插值方法相比,本文方法的校正结果更理想,并且避免了单纯插值方法中金属区域信息的丢失和新伪影的产生。在本文最后对所做的工作做了小结,同时对今后的工作做了一些展望。关键词:金属伪影迭
2、代法投影插值法数学形态学归一化V硕士学位论文StudyonMetalArtifactReductioninComputedTomographyName:HongHong一——Supervisor:LinghongZhou一ABSTRACTCThasbecomeallindispensabletoolforclinicaldiagnosisinhospitalandresearchmethodsincethefirstclinicalCTequipmenthadbeenpublishedfrom1972.Noton
3、lyCanbeusedfordiagnosisofhumandisease,CTimagealsobecommittedtomanyotherapplications.However,differencealwaysexitsbetweenactualandidealCTsystemthatreflectedintheinaccuracyofdata.Differentkindsofartifactswillbeproducedinthereconstructimagewiththeseinaccuratedat
4、a.Accordingtothedifferenceofreasonsandcharacteristicsofartifacts,therearegeometricartifacts,hardeningartifacts,scatteringartifacts,motionartifactsandmetalartifacts.ThemetalartifactsplayanimportantpartinthequalityofCTimage.ItisinevitablethatpatientscalTyorcont
5、ainmetalwhenscannedwithCTinmedicine.Themetalproducesbrightanddarkstreakartifactsinimageafterreconstruction.Becausethepathologicalfeaturesofhumantissueandtheperformanceofartifactsaredifferent,theartifactswillnotleadtomisdiagnosisinnormalconditions.However,when
6、theintensityandareaofartifactislargeenough,theartifactsreducetheimagequalityandevenmaketheimagenotberead.Thecausesofmetalartifactsarerathercomplex.ThemetalartifactsCanleadtobeamhardening,partialvolumeorthedynamicrangeofelectronicdevicesworkingABSTRACTindataac
7、quisition.Inaddition,thereisevidencethatthemotionofmetalisoneofthemainreasonsofartifacts.Obviously,lotsofreasonscancausemetalartifact.Butthebasicreasonisassociatedwitllthemetalcharacterofhighattenuation.ThehighattenuationmakestheX—rayhardandalsoaggravatescatt
8、ering.Aimingatthisproblem,scholarshaveputforwardvariousmetalartifactreduction(MAR)methods.ThesecorrectionmethodsCanbedividedintothreecategories:iterativereconstructionmethod,projectionint
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