核医学影像中的数据处理课件

核医学影像中的数据处理中国科学院高能物理研究所北京市射线成像技术与装备工程技术研究中心贠明凯核医学影像中的数据处理中国科学院高能物理研究所ModernNuclearMedicalImagingAcquireProcessApplyScannersComputers

UsersModernNuclearMedicalImagingOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationDataorganizationListmodeHistgramSinogramLinogramDataorganizationListmodeSinogram——PETSinogram

rθProjectionsandSinogramSinogram——PETSinogramrθProjecSinogram——PETSinogramrθProjectionsandSinogramSinogram——PETSinogramrθProjectSinogram——SPECTSinogram——SPECT2DVS.3DSeptabetweencrystalringsLowersensitivityLowerrandomLowerscatter2DreconstructionNoseptaHighersensitivityHigherrandomHigherscatter3Dreconstructionorhybridreconstruction2DVS.3DSeptabetweencrystaOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationScatterCoincidenceTruesCoincidenceRandomCoincidenceTrueCounts&NoiseScatterCoincidenceTruesCoincNormalizationABCDAttenuationABCDScatterABCDNeedtocorrectthedataNormalizationABCDAttenuationABCorrectionmethodsrandom“deadtime”normalizationscatterattenuationdecayArccorrectionDepthofinteractionMotioncorrectionPartialvolumeAxialofrotationCameraheadtiltCorrectionmethodsrandomArccoRandomFinitetimewindowwith Energywindow CoincidencetimingwindowActivityRandomFinitetimewindowwith RandomTailfittingsimplestSmallchangesintail,greatchangesinestimateEstimationfromsinglesratesMeasurethesinglecountrateoneachdetectorforagiventimewindowSubtractingfromthepromptsbetweendetectorpairSinglesrateismuchlargerthanthatofcoincidenceeventsSinglerateschangeinthesamewayovertimeRandomTailfittingDelayedcoincidencechannelestimationOnechannelisdelayedbeforebeingsenttocoincidenceprocessingSubtractedformpromptcoincidencesAdvantageAccurateSamedeadtimeenvironmentaspromptchannelDisadvantageIncreasedsystemdeadtimeDoublingofthestatisticalnoiseduetorandomDelayedcoincidencechannelesDeadtimecorrectionDecayingsourceexperimentisperformedDeadtimecorrectionDecayingsDeadtimecorrection(con)LookuptableUniformsourceKnownquantityShortlivedLinearextrapolationfromcountrateforagivenlevelofactivityDeadtimecorrection(con)LookNormalizationCausesofsensitivityvariationsSummingofadjacentdataelementsDetectorefficiencyvariationsGeometricandsolidangleeffectsRotationalsamplingTimewindowalignmentStructuralalignmentseptaNormalizationCausesofsensitSummingofadjacentdataelementsGeometricandsolidangleeffectsSummingofadjacentdataelemeRotationalsamplingLORattheedgearesampledlessthanLORclosetothecenterRotationalsamplingLORattheCrystalinterfacefactorsTimewindowalignmentfactorsCrystalinterfacefactorsTimeNormalizationmethods(con)DirectnormalizationSimplestapproachAdequatestatisticalqualityVeryuniformactivitysourcesScatterinnormalizationshouldbesubstantiallydifferentfromnormalimagingNormalizationmethods(con)DirNormalizationmethods(con)Component-basednormalizationNormalizationmethods(con)ComScattercorrectionLORsrecordedoutsideobjectboundarycanonlybeexplainedbyscatterThescatterdistributionisverybroadScatteredcoincidencesfallwithinthephoto-peakwindowmainlyduetoscatteredonceScattercorrectionLORsrecordeScattercorrectionEnergyspectradistributionofscattered511KeVphotonsaccordingtothenumberoftimeseachphotonscattersScattercorrectionEnergyspectScattercorrectionEmpiricalscattercorrectionsFittingthescattertailsDirectmeasurementtechniqueEnergywindowtechniquesDualenergywindowmethodsMultipleenergywindowmethodsConvolutionandde-convolutionSimulation-basedscattercorrectionAnalyticalsimulationMonteCarlosimulationScattercorrectionEmpiricalscFittingthescattertailsSimplestapproachFitananalyticalfunctiontoscattertailsSecondorderpolynomialor1DGaussianCoincidencesoutsidetheobjectareentirelyscattereventsNotalwayswellapproximated,particularlyinthoraxFittingthescattertailsSimplDirectmeasurementtechniqueOnlyapplicabletoPETwithretractableseptaStepsMakeameasurementofthesameobjectwithandwithoutseptaScalingseptaextendedprojectionsfordifferentefficiencySubtractfromprojectionsofpolarangle0EstimatetheobliquescatterbyinterpolationofthedirectplanescatterDirectmeasurementtechniqueOnDualenergywindowmethodsDualenergywindowmethodsDualenergywindowmethodsDualenergywindowmethodsMultipleenergywindowmethodsMultipleenergywindowmethodsScatterCorrectionScatterCorrectionAnalyticalsimulationAnalyticalsimulationScatterCorrectionABSingleScatter-ModelbasedcorrectionCalculatethecontributionforanarbitraryscatterpointusingtheKlein-NishinaequationBeforeScattercorrectionAfterScattercorrectionScatterCorrectionABSingleScaAttenuationcorrectionAttenuationinthebodyisequaltothatofsourcelyingalongthesameLORAttenuationcorrectionAttenuatZaidiH,HasegawaB.JNuclMed2003;44:291-315.SPECTPETZaidiH,HasegawaB.JNuclMeAttenuationcorrection(con)MeasuredattenuationcorrectionCoincidencetransmissiondataLong-livedpositronemitterNormallymorethanonerodsourceareusedSinogramwindowingisappliedprovidelocationofrodImpracticalin3DSinglestransmissiondataShieldedpointtransmissionsourceSeparateblankscanisneededSignificantscatterandbroadbeamAttenuationcorrection(con)MeMeasuredattenuationcorrectionCoincidencemeasurementusingrodsourceTransmissionmeasurementusingpointsourceMeasuredattenuationcorrectioCTscanAdvantageHighstatisticalqualityHighspatialresolutionSignificantreductioninscantimeDisadvantageFasterCT,slowerPETSmallerFOVofCTDifficultyinregistrationvaluesdonotscalelinearlyCTscanAdvantageAttenuationcorrectionforPETTypesoftransmissionimagesCoincidentphotonGe-68/Ga-68(511keV)highnoise15-30minscantimelowbiaslowcontrastSinglephotonCs-137(662keV)lowernoise5-10minscantimesomebiaslowercontrastX-ray(~30-140kVp)nonoise1minscantimepotentialforbiashighcontrastAttenuationcorrectionforPETOtherattenuationcorrectionmethodsCalculatedattenuationRegulargeometricoutlineConstanttissueSegmentedattenuationSegmenttransmissionimageaccordingtotissuetypeAssigningknownattenuationcoefficientsForwardprojectionOtherattenuationcorrectionmattenuationcorrectionattenuationcorrectionAttenuation/ScattercorrectionUniversityofPennsylvaniaPETCenterNoACorScatterCorrACandScatterCorrPhilipsAllegroAttenuation/ScattercorrectionArccorrectionDifferentsamplingdistanceatdifferentradialpositionEqualsamplingdistanceisrequiredinanalyticalmethodInterpolationmethodNearestinterpolationLinearinterpolationB-splineinterpolation(negativevalues!)ArccorrectionDifferentsampliDOI—depthofinteractionDOI—depthofinteractionDOI—depthofinteraction（con）DOI—depthofinteraction（con）DualLayerDualLayerAPointSpreadFunction(PSF)describestheresponseofanimagingsystemtoapointsourceorpointobject.Asystemthatknowstheresponseofapointsourcefromeverywhereinitsfieldofviewcanusethisinformationtorecovertheoriginalshapeandformofimagedobjects.PSFsareusedinprecisionimaginginstruments,suchasmicroscopy,ophthalmology,andastronomy(e.g.theHubbletelescope)tomakegeometriccorrectionstothefinalimage.PointSpreadFunction(PSF)APointSpreadFunction(PSF)MotioncorrectionCardiacmotionandrespirationMotioncorrectionCardiacmotioMotioncorrection（con）GatedframesListmodeMotioncorrection（con）GatedfrRespiratorymotionisdistributedthroughoutthewholebodyImpactisrarelyondetection,butoftenaffectsquantitationStaticwholebodySinglerespiratoryphase(1of7,sonoisier)<1cclesiononCTWhole-bodyrespiratorygatedPET/CT:PatientsRespiratorymotionisdistribuPartialvolumeeffectCharactersObjectorstructurebeingimagedonlypartiallyoccupiesthesensitivevolumeofscannerSignalamplitudebecomesdilutedwithsignalsfromsurroundingstructuresThedegreeofunderestimationofradioactivityconcentrationwilldependnotonlyonitssizebutalsoontherelativeconcentrationinsurroundingstructuresCorrectionmethodsResolutionrecoveryUseofanatomicalimagingdataPartialvolumeeffectCharacterAPointSpreadFunction(PSF)describestheresponseofanimagingsystemtoapointsourceorpointobject.Asystemthatknowstheresponseofapointsourcefromeverywhereinitsfieldofviewcanusethisinformationtorecovertheoriginalshapeandformofimagedobjects.PSFsareusedinprecisionimaginginstruments,suchasmicroscopy,ophthalmology,andastronomy(e.g.theHubbletelescope)tomakegeometriccorrectionstothefinalimage.PointSpreadFunction(PSF)APointSpreadFunction(PSF)核医学影像中的数据处理课件Partialvolumeeffect——MAPPartialvolumeeffect——MAPassumptions:cameramovesalongcircularorbitorbitisreproducible

calibrationmethodfindssystemgeometryassumptions:problem1:tiltingdetectorassumption:cameramovesalongcircularorbitproblem1:tiltingdetectorassAOR—AxialofrotationOffsetofAORRotationofAORNutationofAORAOR—AxialofrotationOffsetofCameraheadtiltHeadsneedtobeexactlyparalleltoaxisofrotationCorrectalignmentHeadtiltCameraheadtiltHeadsneedtopinholecalibrationDirkBequé,KathleenVunckxpinholecalibrationDirkBequé,circularorbitcircularorbit+newmodelextension2:circularorbit+arbitrarysmalldeviationsmeasurementmodelMichelDefrise,ChrisVanhovecircularorbitcircularorbit+extension2:circularorbit+arbitrarysmalldeviationsoldnewtranslationsrotations1mm-3mm1.5mm-1.5mm1.5mm-1mm1o-2o1.5o-1.5o3.5o-2.5o1mm1.21.41.61.82mmextension2:circularorbit+OutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationRebinningConvert3Ddatato2DRebinningConvert3Ddatato2DSSRBandMSRBSSRB-Single-slice

rebinningDetection:centersliceSimpleFastResolutionlossMSRB-Multi-slicerebinningDistributealongallintermediateslicesDe-blurringalongz-axisSSRBandMSRBSSRB-Single-slicFourierrebinningFourierrebinningOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationImagereconstructionAnalyticalFBPBPFFDK3DRP…IterativeARTMLEMOSEMOSLSMAP…ImagereconstructionAnalyticalAnalyticalalgorithmsForexample,FBP(FilteredBack-projection)TreattheunknownimageascontinuousPoint-by-pointreconstructionRegulargridpointsarecommonlychosenTreatprojectionprocessaslineintegraltheoreticallyAnalyticalalgorithmsForexamp解析重建-FBPFBP解析重建-FBPFBPbackprojection(BP)=summationofprojectionsbackprojection(BP)=summatifilteredbackprojection(FBP)filteredbackprojection(FBP)FDKFeldkamp、Davis、KressFDKFeldkamp、Davis、KressFDKFDK3DRP—Re-projection3DRP—Re-projectionStepsof3DRPExtract2DsinogramsReconstructeachwith2DFBPandstacktoform3DimageForwardprojecttocalculatemissingLORsExtract2DprojectiondataofallobliqueslicesTake2DFouriertransformBackprojectdatathrough3DimagematrixRepeatforallanglesandobliqueslicesStepsof3DRPExtract2DsinogWhatisiterativereconstructionDiscretemeasurements,discreteimageOptimizationWhatisiterativereconstructiAttractionsofiterativemethodsEitherconsistentorinconsistentisOKComplexgeometryPhysicaleffectsanddetectionprocessescanbemodeledNon-negativityGreatreducingstreakingartifactsBettercontrastrecovery……AttractionsofiterativemethoClassificationofiterationreconstructionmethodsART(algebraicreconstructiontechniques)MART(multiplicativeART)AART(additiveART)SIRT(simultaneousiterativereconstruction)SMART(simultaneouslyMART)BI-ART(blockiterativeART)BI-SMART(blockiterativeSMART)RBI-SMART(rescaledBI-SMART)ClassificationofiterationreStatisticalalgorithmsMAP:MaximizetheconditionalprobabilityP(image|data)MLEM:MaximizetheprobabilityP(data|image)StatisticalalgorithmsMAP:Statisticalalgorithms—GaussianassumptionPisprojectioncolumnmatrix,Aissystemmatrix,Fimagecolumnmatrix,CisthecovariancematrixofthedataAssumedallstandarddeviationsareidenticalandequalto1,idealizedparallelprojection,perfectresolutionandnoattenuationorotherdegradingaffectsStatisticalalgorithms—GaussiaStatisticalalgorithms—PoissonassumptionStatisticalalgorithms—Poisson实测数据迭代重建-MLEM&OSEM正投影比较更新重建MLEM,OSEM,....likelihooditeration实测数据迭代重建-MLEM&OSEM正投影比较更新重建MLESinogramrθSubset1Subset2Subset3Subset41324SubsetorderSinogramrθSubset1Subset2Subs012341040orderedsubsets1iterationof40subsets(2projpersubset)012341040orderedsubsets1iterSystemmatrixScangeometryCollimator/detectorresponseAttenuationScatter(object,collimator,scintillator)Dutycycle(dwelltimeateachangle)DetectorefficiencyDead-timelossesPositronrangeNon-colinearityCrystalpenetrationSystemmatrixScangeometryConsiderationsofsystemmatrixQuantitativeaccuracySpatialaccuracyComputationtimeStoragespaceModeluncertaintiesArtifactsduetooversimpleifications……ConsiderationsofsystemmatriSystemmatrixtricksFactorizeSymmetrySparsenessApproximationPartialMonteCarlo……SystemmatrixtricksFactorizeSystemmatrixmodelSystemmatrixmodelReconstructionimageofuniformsourceReconstructionimageofuniforFBPVS.OSEMFBP—analyticalPros：SinglepassLinearFastCons：StreakartifactPoorresolutionCorrectionnotbuilt-inOSEM—iterationPros：BetterresolutionBettercontrastLowernoiseCons：ExtensivetimeconsumingMemoryconsumingRequiredusertrainingFBPVS.OSEMFBP—analyticalOSEMFBPVS.OSEMPhantomtest(left)Clinicalresults(right)FBPVS.OSEMPhantomtest(leftOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImageregistrationandfusionDICOMandPACSOutlineDataorganizationImageRegistrationPETCTPET/CTImageRegistrationPETCTPET/CTVoxelbasedimageregistrationImageRegistrationVoxelbasedimageregistration

ImageRegistration算法流程图相似性测量一般用到的函数有：相同模态图像：残差（sumofsquaredifference）不同模态图像：互信息（mutualinformation）一般用来做配准的优化算法有：六参数或十二参数的优化一般使用Powell优化算法多参数优化一般使用LBFGS（limited-memoryBroyden–Fletcher–Goldfarb–Shanno）优化算法（由牛顿算法演变而来）

ImageRegistration算法流程图相似性测量ImageFusionAlphaBlendingbasedAdaptivealphablendingAlphablendingAdaptiveAlphablendingImageFusionAlphaBlendingbasOutlineDataorganizationCorrectionmethodsRebinningImagereconstructionImager