锥束螺旋CT的迭代算法研究

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1、中北大学硕士学位论文锥束螺旋CT的迭代算法研究姓名：薛震申请学位级别：硕士专业：应用数学指导教师：潘晋孝20090425中北大学硕士学位论文AbstractComputedTomography(CT)isatechnologywithwhichwecanknowthestructureofanobjectinthewayofnon．destruction．UptonOWithasbeenusedwidelyinfieldsofsuchasmedicaldiagnosis．nondestructiveexamination，andaeronauticsandastr

2、onauticsetc．Cone—beamCThasmuchadvantageover2Dparallel．beamandfan。beamCTintheaspectsofspeedinobtainingdata，spatialresolutionandtheutilizationratioofrays．NowCTincommerceareturningtousingcone．beamCT．Helicalcone．beamCT-thecone．beamCTwithhelicalscanningpath，hasbeenknownforusinglessX·rays，s

3、canningfastwithlargevolume．highaccuracyofreconstruction．SoithasbecomeahottopicinthefieldofCTimagereconstruction．Atpresenttheresearchonreconstructionalgorithmsofhelicalcone．beamCTisgenerallybasedonanalyticalgorithms，andthesemethodsusuallyneedcompleteprojectiondata．Inpracticecompletepro

4、jectiondatacannotbeobtainedoutofobjectivecause，SOanalyticmethodsfailinthiscase．IterativealgorithmshavegottenmoreandmoreattentionforitCanreconstructimagessimplyandeffectivelyandCanreconstructimageswitIlincompleteprojectiondata．Someexploratorystudyhasbeenissuedonhelicalcone。beaminthisPa

5、Der．Themaincontextisasfollows：Firstly,afastandreal—timemethodofobtainingprojectionmatrixisproposedaccordingtothecharacteristicofhelicalcone．beamCT．Theanalysisoncomplexityisdone．Theeffectivenessofproposedalgorithmsisprovedbysomeexperiments．Secondly,theeffectofpitchonreconstructedresult

6、isgoRenthroughreconstructingimageswithprojectiondataindifferentpitches．TheexperimentalresultsshowthatthepitchCanusuallybechosenas0．5．1．5timestheheightofdetectorontheconditionthatcone．beameffectiSnotobvious．Thusthereconstructedspeedcanbefastened．theamountofradiationcallbereduced，andbet

7、terreconstructedresultscanbeobtained．Lastly,theiterativealgorithmsaredonewiththeprojectiondataincaseofsparseandsight—limited．Theexperimentalresultsshowthatbetterimagescanstillbegottenbyusingiterativereconstructionalgorithmwithincompleteprojectiondata．Ontheconditionthattheamountofproje

8、ction