ct中金属伪影的校正分析

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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