from sinograms to surfaces a direct approach to the segmentation of tomographic datanew

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1、FromSinogramstoSurfaces:ADirectApproachToTheSegmentationOfTomographicDataVidyaElangovanandRossT.WhitakerSchoolofComputing,UniversityofUtahSaltLakeCity,UT,USAToappear:InternationalConferenceonMedicalImageComputingandComputer-AssistedIntervention(MICCAI),October2

2、001,Utrecht,TheNetherlandsAbstract.Underidealcircumstancestheproblemoftomographicreconstructioniswell-posed,andmeasureddataaresufficienttoobtainaccurateestimatesofvolumedensities.Insuchcasessegmentationandsurfaceestimationfromthereconstructedvolumearejustified.In

3、othersituationsthereconstructedvolumesarenotsuitableforsub-sequentsegmentation.Thiscanhappeninthecaseofincompletesinograms,noiseinthemeasurementprocess,ormisregistrationoftheviews.Thispaperpresentsadirectapproachtothesegmentationofincompleteandnoisytomographicd

4、ata.Thestrategyistoimposeafairlysimplemodelonthedata,andtreatsegmentationasaprob-lemofestimatingtheinterfacebetweentwosubstancesofsomewhathomogeneousdensity.Thesegmentationisachievedbysimultaneouslydeformingasurfacemodelandupdatingdensityparametersinordertoachi

5、eveabestfitbetweentheprojectedmodelandtheinputsinograms.Thedeformationisimplementedwithlevel-setsurfacemodels,calculatedattheresolutionoftheinputdata.Severalcomputationalinnovationsmaketheapproachfeasi-blewithstate-of-the-artcomputers.Theusefulnessoftheapproachi

6、sdemonstratedbyreconstructingtheshapeofspinydendritesfromelectronmicroscopetomographicdata.1IntroductionCertainkindsoftomographicreconstructionproblemsareill-posedduetoincompletesinogramdata.Difficultiesinreconstructingvolumesfromsuchdataareaggravatedbynoiseinth

7、emeasurementsandmisalignmentsamongprojections.Thispaperaddressestheproblemofsegmentationinthecontextofsuchdifficulttomographyproblemsinbiologyandmedicine.Theusualapproachforsegmentation(indeed,anykindofpostprocessing)insuchcasesistoreconstructthevolume,asbestasp

8、ossible,fromthemeasureddatausingstandardtechniquessuchasfilteredbackprojection.Segmentationisthenperformedbasedonthegrey-scalepropertiesofthatvolume.However,theill-posednatur