医学影像设备学课件：CT Princeples.pptx

《医学影像设备学课件：CT Princeples.pptx》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、CT（ComputedTomography)History、Structure、PrincepleModernCTsystemsemployslipringtechnologytoallowforcontinuousdataacquisition.a)Photographofameasuringsystemduringassemblywithsliprings(left)andcomponents(right)visible.b)Schematicrepresentationofsliprings,whichallowthetransf

2、erofelectricalenergytothex-raycomponentsanddatafromthedetectorsystemtotheimagereconstructionunit.Multi-SourceCT.a,b)Schematicdrawingsofaproposedthree-sourcescannerandofadual-sourcescannerthatwasactuallybuilt.c)PhotooftheSiemensSOMATOMDefinitionFlashdualsourceCTsysteminsta

3、lledintheWestChinaHospitalFromahistoricalperspective,fourscannergenerationsareknowninCT.Headscanners,whichscannedthepatientbytranslationandrotationofthemeasurementsystemwithapencilbeam(a)orasmallfanbeam(b),andfanbeamsystems,inwhichallbodysectionscanbescannedwithacontinuou

4、s360°rotation.The'3rdgeneration',featuringarotatingdetector(c),hasclearlyoutdistancedthe'4thgeneration',whichutilizesstationarydetectorrings(d).EBT:ElectronBeamTomographyX-RayDiscoveryX-raywasdiscoveredbyaGermanscientistRoentgen100yearsago.Thismadepeopleforthefirsttimebea

5、bletoviewtheanatomystructureofhumanbodywithoutoperationButit'ssuperimposedAndwecouldn'tviewsofttissueGodfreyN.Hounsfield,theEnglishengineerwhodevelopedthefirstCTscannerandreceivedtheNobelPrizeinmedicinein1979togetherwiththephysicistA.M.CormackComputedtomography-perception

6、inslices.CTprovidestransversesectionimagesofthehumanbodyindigitalform.Acoordinatesystemthenresultswhichbasicallyconformstotheanatomicalmainaxesandplanes.Analogordigitalimages?Continuousimagingofanatomyorscanningofsingleslices?InearlyCTimages,hereabrainscanproducedin1974wi

7、than80x80imagematrix(a),thecomputeddiscretepictureelementsareclearlyvisible,justasthestepsinthesecondaryreconstructionsgeneratedfromsinglescanstakenwithaspacingof13mm(b).Forvolumescansobtainedinspiralscanningmodeandreconstructionoffinermatrices(c)pictureelementscannotbedi

8、scernedfromanalogimagesanymore;theycanalsobeviewedinthethirddimensionquasi-continuously(d).Whydo