CT成像原理介绍英文版医学知识讲解培训ppt课件

CTCT成像原理介成像原理介绍绍英文英文版医学知版医学知识讲识讲解解CT成像原理介绍英文版医学知识讲解1Computed Tomography CT Basics Principle of Spiral CT Scan Parameter&Image Quality Optimizing Injection Protocols Clinical Applications2CT成像原理介绍英文版医学知识讲解Computed Tomography CT Basics2X-Ray Discovery X-ray was discovered by a German scientist Roentgen 100 years ago.This made people for the first time be able to view the anatomy structure of human body without operation77 But its superimposed 77 And we couldnt view soft tissue3CT成像原理介绍英文版医学知识讲解X-Ray Discovery X-ray was dis3l My name is Godfrey Hounsfieldl I work for the Central Research Labs.of EMI,Ltd in Englandl I developed the the first clinically useful CT scanner in 1971History of Computed Tomography Early 1970s1963-Alan Cormack developed a mathematical method of reconstructing images from x-ray projections4CT成像原理介绍英文版医学知识讲解 My name is Godfrey Hounsfiel4 For the first time we could view:CT Broke the Barrier-Tomographic or“Slice”anatomy-Density difference77 But its time consuming77 And resolution needs to be improved5CT成像原理介绍英文版医学知识讲解 For the first time we could v5Concept of X-ray AttenuationAn X-ray beam passing throughthe body is attenuated(loses itsenergy)by:AbsorptionScatteringIncident X-rayTransmitted raySCATTERED X-SCATTERED X-RAYSRAYSBODYTISSUEAbsorption by the tissue is proportional to the densityLessdensetissueMoredensetissueMORE ATTENUATIONLESS ATTENUATION6CT成像原理介绍英文版医学知识讲解Concept of X-ray AttenuationA6How does CT Work?How does CT Work?Recon.&postpro.Data acquisitionX-ray generation7CT成像原理介绍英文版医学知识讲解How does CT Work?Recon.&post7X-ray goes through collimator thereforepenetrate only an axial layer of the object,called sliceHow does CT Work?How does CT Work?8CT成像原理介绍英文版医学知识讲解X-ray goes through How does CT8Patient is placed in the center of the measurement fieldX-ray is passed through the patients slice from many direction along a 360 pathThe transmitted beams are captured by the detectors which digitizes these signalsThese digitized signals called raw data are sent to a computer which create the CT imageHow does CT Work?How does CT Work?9CT成像原理介绍英文版医学知识讲解Patient is placed in the cente9The object slice is divided into small volume elements called voxels.Each voxel is assigned a value which is dependent on the average amount of attenuationHow is CT Image generated?10CT成像原理介绍英文版医学知识讲解The object slice is divided in10The attenuation values are transferred to the computer where they are coded&used to create a slice imageHow is CT Image generated?11CT成像原理介绍英文版医学知识讲解The attenuation values are tra11CT Generations&Design“Generation”is used to label CT tube-detector designs3rd Generation Design3rd Generation DesignRotating tube&detectorRotating tube&detector4th Generation Design4th Generation DesignFixed ring detectorFixed ring detector12CT成像原理介绍英文版医学知识讲解CT Generations&Design“Genera12Slip-ring TechnologyPower is transmitted through parallel sets of conductive ringsinstead of electrical cables Continuous Gantry Rotation Prerequisite for Spiral CTNon Slip-ring ScannerNon Slip-ring ScannerSlip-ring ScannerSlip-ring Scanner13CT成像原理介绍英文版医学知识讲解Slip-ring TechnologyPower is t13Computed Tomography CT Basics Principle of Spiral CT Scan Parameter&Image Quality Optimizing Injection Protocols Clinical Applications14CT成像原理介绍英文版医学知识讲解Computed Tomography CT Basics14What is Spiral Scan?-just 4“C”Continuously rotating tube/detector systemContinuously generating X-rayContinuously table feedContinuously data acquisition15CT成像原理介绍英文版医学知识讲解What is Spiral Scan?-just 415Reconstruction of arbitraryslices(either contiguous or overlapping)within thescanned volume Distance between the slices is called IncrementABVolume DataContinuous data acquisition16CT成像原理介绍英文版医学知识讲解Reconstruction of arbitraryABV16Increment Slice ThicknessIncrement=Slice ThicknessIncrement=Slice Thickness No Overlap No Overlap No Gaps No GapsContiguous Image Reconstruction17CT成像原理介绍英文版医学知识讲解IncrementSlice ThicknessIncr17Increment Overlap SliceThicknessOverlapping Image ReconstructionIncrement Slice ThicknessIncrement Slice ThicknessIncrement Slice Thickness Gaps between slices Gaps between slices Images are further apart Images are further apart Less images created Less images createdImage Reconstruction with GapsIncrement Slice Thickness19CT成像原理介绍英文版医学知识讲解Increment Slice ThicknessIma19Standard CT/Slice ImagingStandard CT/Slice ImagingDeep InspirationDeep InspirationShallow InspirationShallow Inspiration Misregistration due to different Misregistration due to different respiratory levels between slices respiratory levels between slicesPartial Volume EffectPartial Volume Effect Unable to resconstruct images at Unable to resconstruct images at arbitrary position arbitrary position Slice imaging is slow Slice imaging is slow20CT成像原理介绍英文版医学知识讲解Standard CT/Slice ImagingDee20 Scan the whole region of Scan the whole region of interest in one breath hold interest in one breath hold Reconstruction of overlapping Reconstruction of overlapping images without additional dose images without additional dose Retrospective reconstruction Retrospective reconstruction of slices in arbitrary position of slices in arbitrary position within the scanned volume within the scanned volume No gaps since radiation always No gaps since radiation always transmits the whole volume transmits the whole volumeSpiral CT/Volume ImagingSpiral CT/Volume Imaging21CT成像原理介绍英文版医学知识讲解 Scan the whole region of Re21Computed Tomography CT Basics Principle of Spiral CT Scan Parameter&Image Quality Optimizing Injection Protocols Clinical Applications22CT成像原理介绍英文版医学知识讲解Computed Tomography CT Basics22Scan ParametersX-ray Tube Voltage(kVp)X-ray Tube Current(mA)Scan Time(s)Slice thickness or Collimation(mm)Table Speed(Table Speed(mm/rot)mm/rot)or Feed per 360 rotationor Feed per 360 rotation Pitch Pitch Interpolation Process Interpolation Process Increment(mm)Increment(mm)23CT成像原理介绍英文版医学知识讲解Scan ParametersX-ray Tube Volt23Table Speed&Pitch Table Speed is defined as distance traveled in mm per 360 rotationPitch =Table Feed per rotation Collimation24CT成像原理介绍英文版医学知识讲解Table Speed&Pitch Table Spee2410mm 10mm P1P110mm P210mm P23030s s30s30sMore Coverage inMore Coverage inthe same time with the same time with extended Pitch!extended Pitch!Pitch 2 covers Pitch 2 covers 2x2xdistance as distance as Pitch 1Pitch 125CT成像原理介绍英文版医学知识讲解10mm P110mm P230s30sMore Cover25Scan Range=300mm10mm P110mm P110 mm/s10 mm/s10mm P210mm P220 mm/s20 mm/s30s15sCover the same volume in shorter time with extended PitchCover the same volume in shorter time with extended Pitch26CT成像原理介绍英文版医学知识讲解Scan Range=300mm10mm P110mm 26To reduce artifacts due to table motion during spiral scanning,we use a special reconstruction process called INTERPOLATION Interpolation Interpolation Converts volume data into slice Converts volume data into slice imagesimagesInterpolation Algorithm27CT成像原理介绍英文版医学知识讲解To reduce artifacts due to tab27Wide AlgorithmWide AlgorithmSlim AlgorithmSlim Algorithm2 x 360 2 x 360=720=720raw dataraw data2(180+52)2(180+52)=464=464raw dataraw dataWide algorithm produces a broader image thicknessWide algorithm produces a broader image thicknessWide algorithm uses more raw data=less image noiseWide algorithm uses more raw data=less image noise28CT成像原理介绍英文版医学知识讲解Wide AlgorithmSlim Algorit28PITCH 2PITCH 2PITCH 1PITCH 1Pitch 2 scanning produces a broader image thicknessPitch 2 scanning produces a broader image thicknessPitch 2 scanning does not increase image noisePitch 2 scanning does not increase image noise30%increase in 30%increase in image thicknessimage thicknesswith Pitch 2 with Pitch 2 29CT成像原理介绍英文版医学知识讲解PITCH 2PITCH 1Pitch 2 scanning29Slice Sensitivity Profile(SSP)SSP describes the effective slice thickness of an image and to what extent anatomy within that slice contribute to the signalSSPRESOLUTIONAll points within the slice contribute equally&points outside of the slice do not contribute to the image at all.Image signalIdeal SSPZ-axis(mm)Collimation=width of x-ray beam=slice profile30CT成像原理介绍英文版医学知识讲解Slice Sensitivity Profile(SS30Slice Profile(SP)Effective slice thickness of an image Slice ProfileResolutionFactors influencing Slice Profile Collimation Collimation Pitch Pitch Interpolation algorithm(360 or 180)Interpolation algorithm(360 or 180)31CT成像原理介绍英文版医学知识讲解Slice Profile(SP)Effective sl31Factors influencing SSPCollimator width collimation=SSPSpiral CTTable speed or PitchInterpolation Algorithm=mathematical process required to reconstruct axial images from the spiral volume data set32CT成像原理介绍英文版医学知识讲解Factors influencing SSPCollima32Pitch&Slice Profile33CT成像原理介绍英文版医学知识讲解Pitch&Slice Profile33CT成像原理介33Slim vs Wide SSP ComparisonSlice Profile Slim%Broaden Wide%BradenPitch One 5.0 mm 0 6.3 mm 26Pitch Two 6.5 mm 30 10.8 mm 11634CT成像原理介绍英文版医学知识讲解Slim vs Wide SSP ComparisonS34WIDE720 degreeMore photonsSLIM464 degreeLess photons SSP Spatial resolutionSSPSpatialresolutionSmoother imageNoisier image35CT成像原理介绍英文版医学知识讲解WIDESLIM SSPSSPSmoother imag35Slim-AdvantagesImproved Z ResolutionReduced partial volume artifactsSlim+extended PitchLonger coverageSame coverage with shorter scan time or thinner slicesLess radiation dose36CT成像原理介绍英文版医学知识讲解Slim-AdvantagesImproved Z 36CT成像原理介绍英文版医学知识讲解培训ppt课件37Slice Profile Comparison38CT成像原理介绍英文版医学知识讲解Slice Profile Comparison38CT成像38 Lesion smaller than 1cm SCAN RANGE=150mm 10/10/10 10/10/10(15s)(15s)5/10/5 5/10/5(15s)(15s)Slice Profile=10mm Slice Profile=6.5mmOptimizing the Scanning Parameters39CT成像原理介绍英文版医学知识讲解 Lesion smaller than 1cm S39Smallest Possible Effective Slice ThicknessScan Length Scan Length(mm)(mm)Scan Duration Scan Duration(s)(s)Table Table Speed Speed(mm/s)(mm/s)SmallestSmallestCollimation Collimation(mm)(mm)Scan DurationScan DurationDepends on the scan length&patients breath-hold complianceTable SpeedTable SpeedPitch FactorPitch Factor1 Pitch 2 to cover the whole volume in one breath-hold40CT成像原理介绍英文版医学知识讲解Smallest Possible Effective Sl40Computed Tomography CT Basics Principle of Spiral CT Scan Parameter&Image Quality Optimizing Injection Protocols Clinical Applications41CT成像原理介绍英文版医学知识讲解Computed Tomography CT Basics41Peripheral vein eg.antecubital vein 19-20 gauge needle or IV catheterVolumeFlow RateConcentrationInjection Protocols300 mg I/ml300 mg I/mlnon-ionic contrastnon-ionic contrast2-5 ml/s 2-5 ml/s cardiac output cardiac output80-150 ml80-150 ml patients weight®ion of interestpatients weight®ion of interestSiteScan DelayDelay between injection initiation&the Delay between injection initiation&the start of the scan sequencestart of the scan sequence42CT成像原理介绍英文版医学知识讲解Peripheral vein eg.antecubita42Tailoring Scan&Injection ProtocolsInjection Duration must be Injection Duration must be equal to or greater thanequal to or greater than Scan Time Scan Time5050100100150150200200250250TimesTimesHUHUCONTRASTCONTRAST5050100100150150200200250250TimesTimesHUHUCONTRASTCONTRASTNaClNaClBolus Duration scan timeBolus Duration scan timeInsufficient,inhomogeneousInsufficient,inhomogeneous opacificationopacificationBolus Duration=scan timeBolus Duration=scan timeUniform,maximum opacificationUniform,maximum opacificationEnhancement Curve of the Target RegionEnhancement Curve of the Target Region43CT成像原理介绍英文版医学知识讲解Tailoring Scan&Injection Pro435050100100150150200200250250TimesTimesHUHUOptimal WindowOptimal WindowEarlyEarlyTime-density curveTime-density curveof the target regionof the target regionLateLateContrast Bolus TimingDetermines optimal scan delay for spiral CTA sequenceCONTRASTCONTRASTNaClNaCl44CT成像原理介绍英文版医学知识讲解50100150200250TimesHUOptimal44Test Bolus ProcedureImaging VolumeImaging Volumefor spiral CTAfor spiral CTA 10-20 ml of contrast is injected 10-20 ml of contrast is injected at the chosen rate for spiral at the chosen rate for spiral After a delay of 8-10s,low-dose,After a delay of 8-10s,low-dose,single-level axial images are single-level axial images are acquired every 2s at the starting acquired every 2s at the starting point of the imaging volume point of the imaging volume Dynamic scans at Dynamic scans at this positionthis position Dynamic Evaluation to generate Dynamic Evaluation to generate a Time-density curve a Time-density curve45CT成像原理介绍英文版医学知识讲解Test Bolus ProcedureImaging Vo45Dynamic EvaluationTime-density curve Scan Delay Peak Enhancement Time Dynamic ScansROI placed in the Aorta46CT成像原理介绍英文版医学知识讲解Dynamic EvaluationTime-density46Computed Tomography CT Basics Principle of Spiral CT Scan Parameter&Image Quality Optimizing Injection Protocols Clinical Applications47CT成像原理介绍英文版医学知识讲解Computed Tomography CT Basics47 Arterial Phase Arterial Phase Venous Phase Venous PhaseDual Phase Liver ExamLiver Metastases48CT成像原理介绍英文版医学知识讲解 Arterial Phase Venous PhaseDu48Single Plane Imaging with Multiplanar Results2D reconstruction based on a serial 2D reconstruction based on a serial of axial images along a certain axisof axial images along a certain axisSagittalSagittalCoronalCoronalOblique recon.of AortaOblique recon.of Aorta49CT成像原理介绍英文版医学知识讲解Single Plane Imaging with Mult49CT AngiographySpine 3D image:AVMSpine 3D image:AVMMax.IntensityMax.IntensityProjectionProjectionSurface ShadedSurface ShadedDisplay(3D)Display(3D)Femoral Arteries CT AngiogramFemoral Arteries CT Angiogram50CT成像原理介绍英文版医学知识讲解CT AngiographySpine 3D image:503D Post-processing3D BronchoscopyLesion in the right upper lobe branchLesion in the right upper lobe branchColour Segmentation 3D Colour Segmentation 3D 51CT成像原理介绍英文版医学知识讲解3D Post-processing3D Bronchosc51Volume Rendering TechniqueTransparent imageTransparent imageTransparent&color imageTransparent&color imageSolid ImageSolid Image52CT成像原理介绍英文版医学知识讲解Volume Rendering TechniqueTran52Virtual Endoscopy Real Time Fly through Real Time Fly through Reverse Perspective Reverse Perspective Axial Image reference Axial Image reference High Resolution High ResolutionBronchoscopyBronchoscopy53CT成像原理介绍英文版医学知识讲解Virtual Endoscopy Real Time F5354CT成像原理介绍英文版医学知识讲解The END54CT成像原理介绍英文版医学知识讲解54