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1、成像理论与技术万遂人Email:srwan@seu.edu.cnCell:139-5178-0069教材：《医学成像原理》，科学出版社，2012.1.现代医学的几次革命性突破，跟医学成像技术有关。21世纪被称为“创新医学影像的世纪”。MolecularMedicine1913MedicalX-Ray1976ComputedTomography19832005+2000Digital x-RayImagingMRImaging1993DigitalUltrasound美国BME排名前50位的大学都开设了
2、“医学成像”课程，作为研究生专业核心课程。医学成像都是射线能量和人体组织相互作用形成的。电磁波成像电磁波对25cm厚人体软组织的投射系数声波成像超声回波成像超声非线性成像不同成像方法互补性ImagingDefinitionsObjectfunction-therealspacedescriptionoftheactualobject.Resolution-thecollectedimageisonlyanapproximationoftheactualobject.Theresolutiondescr
3、ibeshowaccuratethespatialmappingis.Distortions-describesanyimportantnonlinearitiesintheimage.Iftherearenodistortions,thentheresolutionisthesameeverywhere.Fuzziness-describeshowwellwehavedescribedtheobjectwewishtoimage.Contrast-describeshowclearlywecandi
4、fferentiatevariouspartsoftheobjectintheimage.SignaltoNoiseratioTherearetwoverybasicproblemsinimageanalysis:Giventhedata,anestimationoftheinstrumentfunctionanda(statistical)modelofthenoise,recovertheinformation(anestimationoftheobjectfunction),Employinga
5、suitablemodel,interpretthisinformation.Sohereourgoalsare:Designanalgorithmtocomputetheobjectfunctiongivencertaindataonthescatteringfield,anestimationofthepointspreadfunction,andanestimationoftheexperimentalnoise.Findawayofrecoveringanappropriatesetofmat
6、erialparametersfromtheobjectfunction,Setuptheexperimentsuchthatobjectfunctionreflectstheparameterofinterest,Designtheexperimentsuchthattheimagingexperimentcloselyapproximatesalinearsystem(orthatthenon-linearitiesaredealtwithcorrectly)andsuchthatthepoint
7、spreadfunctionisnarrowandofdefiniteshape.Considerthesimplemodel,aplaneofsourcesI(x,y)mappedontoaplaneofdetectorsE(x,y).Thedetectorsmeasurephotonintensity(energy)anddosoinalinearfashion(iftwicethephotonintensityimpingesonthedetectoritreturnsasignaltwicea
8、slarge).Question:whatwouldhappenifthedetectorssaturated?Thereisamappingfromthesourcetothedetector,E(x,y)=S{I(x,y)}andthemappingisalinearfunctionalso,S{aI1(x,y)+bI2(x,y)}={S{aI1(x,y)}+S{bI2(x,y)}aandbarescalars.Whenwemodelthesyste
