CT成像原理介绍(英文版)资料讲解.ppt

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1、CT成像原理介绍(英文版)X-RayDiscoveryX-raywasdiscoveredbyaGermanscientistRoentgen100yearsago.ThismadepeopleforthefirsttimebeabletoviewtheanatomystructureofhumanbodywithoutoperationButit'ssuperimposedAndwecouldn'tviewsofttissueMynameisGodfreyHounsfieldIworkfortheCentralResearchLabs.ofEMI,LtdinEnglan

2、dIdevelopedthethefirstclinicallyusefulCTscannerin1971HistoryofComputedTomographyEarly1970s1963-AlanCormackdevelopedamathematicalmethodofreconstructingimagesfromx-rayprojectionsForthefirsttimewecouldview:CTBroketheBarrier-Tomographicor“Slice”anatomy-DensitydifferenceButit'stimeconsumingAn

3、dresolutionneedstobeimprovedConceptofX-rayAttenuationAnX-raybeampassingthroughthebodyisattenuated(losesitsenergy)by:AbsorptionScatteringIncidentX-rayTransmittedraySCATTEREDX-RAYSBODYTISSUEAbsorptionbythetissueisproportionaltothedensityLessdensetissueMoredensetissueMOREATTENUATIONLESSATTEN

4、UATIONHowdoesCTWork?Recon.&postpro.DataacquisitionX-raygenerationX-raygoesthroughcollimatorthereforepenetrateonlyanaxiallayeroftheobject,called"slice"HowdoesCTWork?PatientisplacedinthecenterofthemeasurementfieldX-rayispassedthroughthepatient’sslicefrommanydirectionalonga360°pathThetransmi

5、ttedbeamsarecapturedbythedetectorswhichdigitizesthesesignalsThesedigitizedsignalscalledrawdataaresenttoacomputerwhichcreatetheCTimageHowdoesCTWork?Theobjectsliceisdividedintosmallvolumeelementscalledvoxels.EachvoxelisassignedavaluewhichisdependentontheaverageamountofattenuationHowisCTImag

6、egenerated?Theattenuationvaluesaretransferredtothecomputerwheretheyarecoded&usedtocreateasliceimageHowisCTImagegenerated?CTGenerations&Design“Generation”isusedtolabelCTtube-detectordesigns3rdGenerationDesignRotatingtube&detector4thGenerationDesignFixedringdetectorSlip-ringTechnologyPoweri

7、stransmittedthroughparallelsetsofconductiveringsinsteadofelectricalcablesContinuousGantryRotationPrerequisiteforSpiralCTNonSlip-ringScannerSlip-ringScannerComputedTomographyCTBasicsPrincipleofSpiralCTScanParameter&ImageQualityOptimizingInjectionProtocolsClinicalAp