最新Computational methods for microwave medical imaging微波医学成像的计算方法-药学医学精品资料.ppt

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1、最新Computationalmethodsformicrowavemedicalimaging微波医学成像的计算方法-药学医学精品资料OutlineOverviewForwardfieldmodelingaccuracyandefficiencyImplementationoftheFDTDmethod3DmicrowaveimagingSystemandresultsReconstructionefficiencyEstimationmodelTheadjointmethodandthenodaladjointapprox

2、imationSVDanalysisoftheJacobianmatrixPhasesingularityandphaseunwrappingScatteringnullsDynamicphaseunwrappinginimagereconstructionConclusions2004-12-222Qianqian'sPhDThesisDefenseCharacteristicsofDartmouthMicrowaveimagingsystemTomography,wide-bandoperatingfrequency,sm

3、alltarget,lossybackground,simpleantennaModelingnonlinearscatteredfield,nonlinear(iterative)parameterestimationAdvantageofaccessinginvivodata(smallanimal/patientbreastimaging),firstclinicalmicrowaveimagingsystemintheUS2004-12-223Qianqian'sPhDThesisDefenseFDTD(FiniteD

4、ifference-TimeDomain)methodinmicrowavetomographyConceptuallystraightforward,easytoprogramGoodabsorptionboundaryconditionMarching-On-Timefeature(MF,initialfield)LowercomputationalcomplexityEasytoparallelize2004-12-227Qianqian'sPhDThesisDefense2DFDTDdual-mesh2004-12-2

5、28Qianqian'sPhDThesisDefenseUsingFDTDforwardmodelinginaniterativereconstructionStartSetinitialguessEvaluateforwardsolutionComparepredictedfieldmeasuredfieldEvaluateJacobianSolveforparameterupdatesGoodenough?FEM:AssembleAAssemblebApplyBCSolveAx=bFDTD:Computeupdatecoe

6、ff.dot=1:timestepUpdateEUpdateHIfsteady-state?breakenddoamp&phaseextractionEndnoyes2004-12-229Qianqian'sPhDThesisDefenseComputationalefficiencycomparisonFE/BE(directmethod)Matrixsize:Half-bandwidth:BandedLUdecomposition:flop=2np2+2npCholeskydecomposition:flop=np2+7n

7、p+2n+n*flop(sqrt)LDLTdecompositionflop=np2+8np+nFDTD:flop=Nsteady*flopiter=56sqrt(2)N(N+2NPML)2cmax/cbk2004-12-2210Qianqian'sPhDThesisDefenseFLOPcountvs.meshsizeTheresultmaybedifferentif:FEusesaniterativesolverusesapproximatedBCFDTDusepolarcoordinateseparateworkingv

8、olumeandPMLlayer2004-12-2211Qianqian'sPhDThesisDefenseForwardfieldaccuracy2D/3Dscalar/3Dvectorinhomogeneousandinhomogeneouscases2004-12-2