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1、NuclearMedicinePhysicsandInstrumentationMyUnderstandingofNM(Clinical)MedicineMedicalImagingandNuclearMedicineNuclearMedicineDiagnosisTherapyNMPhysicsNuclearPhysicsNuclearInstrumentTeacher：LuyiZhou(周绿漪)Dept.ofNuclearMedicineTel：85422330Topics.AtomandNucleus.ModesofRadioactiveDecay.DecayofRadioactivit
2、y.InteractionofParticleswithMatter.RadiationDetectors.InstrumentationforRadiationDetection.Camera.SPECT.PET.DevelopmentofNuclearMedicineInstruments.AtomandNucleus（I）AtomlAtomNucleusElectronBohrModelShellEnergyLevelBindingEnergyAtomicEmissionsCharacteristicXRayAugerEffectEnergyLevelandBindingEnergyAt
3、omicEmissions:CharacteristicXRayAtomicEmissions:AugerEffect（II）Nucleus1.CompositionandNotationCompositionnucleon：protonandneutronlNotationExample:Shortened：Acceptable:X-AOr:I-131Mass numberElement symbolAtomic numberNumber of neutrons2.NuclidesandtheirclassificationNuclide:AnAtomwithgivenAandZ，exact
4、arrangementofnucleoninthenucleus,andmeasurablelifetime.Isotope：Nuclideswiththesamenumberofprotons,butdifferentnumbersofneutrons.(Example:I-125,I-127,I-131areisotopesofI,andoneanother）Isomer:NuclideswithidenticalA,Z,andN,butdifferentenergystates.Nuclides:StablenuclidesandRadionuclidesRadionuclides:Na
5、turalradionuclidesandArtificialradionuclides3.ForcesbetweennucleonsNucleonsaresubjecttoelectricalforcesandexchangeforcesElectricalforce：repulsive,longdistance,nonsaturable,weak(eV)Strongforce(exchangeforce)：attractive,shortdistance,saturable,strong(MeV)Whentheforcesarebalanced,thenucleusisstable,ori
6、twilldecay.4、EnergystateofnucleusAnucleusmaybeinoneofthethreeenergystates:Groundstate：moststablestateExcitedstate：extremelyunstable，transientexistencebeforetransformingintootherstateMetastablestate：unstable,butwithrelativelylonglifetimebeforetransformingintoanotherstate.Alsocalledisomericstate.Isome
7、r：Twonuclidesthatdifferfromoneanotherinthatoneisametastablestateoftheotherarecalledisomers（e.g.Tc-99andTc-99m）*Theenergylevelsarewelldefined5.Stableorunstable?lBalanceoftheforceslEnergystateIfUnstableRadioactivedecayRadioactivedisintegrationII.ModesofRadioactiveDecay（I）Terminologies(1)Radioactivedec
8、ay：Aprocessinwhichanunstablenucleustransformsintoamorestableonebyemittingparticlesand/orphotonsandreleasingnuclearenergy.Parent: the unstable radioactive nucleusDaughter: the more stable product nucleus (which may also be radioactive)Transition energy: energy releasedRadionuclide：radioactivenuclidew
9、ithasetofcharacteristicproperties:modeofradioactivedecayandtypeofemissions,thetransitionenergy,andtheaveragelifetime.Radioisotope：theradioactivemember(s)ofanisotopicfamily.（I）Terminologies(2)SpontaneityofradioactivedecayTheexactmomentatwhichagivennucleuswilldecaycannotbepredicted,norisitaffectedtoan
10、ysignificantextentbyeventsoccurringoutsidethenucleus(Eachnucleusdecaysindependently)（II）ModesofRadioactiveDecay1.decay(negatrondecay)：Aprocessinwhichaneutroninthenucleusistransformedintoaprotonandanelectron(particle,negatron).Standardnuclearnotationofdecay:X：parentY：daughterQ：transitionenergy,inMeV：
11、neutrino.neutralparticle,nomass,rarelyinteractwithmatterDecayscheme：Diagrammaticdepictionofradioactivedecay.decaytotheright:atomicnumberincreases.v.v.verticaldistancebetweenthelinesisproportionaltothetransitionenergye.g.DecayofC-14ShareofQ：randomlybetween-andparticleenergydistribution(spectrum)May h
12、ave any energy from 0 to QRarely carries away all QThe average energy is about 1/3 of Q The most possible energy is 1/3 of Q- Particle Kinetic Energy (MeV)RelativeNumberEmitted Particle Spctrum2.（ ，）decayWhen the daughter nucleus is in an excited state, it promptly decays to a more stable state by e
13、mission of a ray. The sequential decay process is (,) decay Decayschemeof133XeEnergySpectrumanditsApplicationComposed of a series of discrete lines The energy distribution is characteristic of the radionuclide.Quantity and space distribution of known radionuclide can be recorded by detecting rayRela
14、tiveNumberEmitted0.050.100.15rayenergy（MeV）1(0.080MeV)2(0.081MeV)3.IsometricTransitionandInternalConversionIsomerictransition(IT)ThedecayofthemetastableorisomericstatebytheemissionofarayInternalconversion(IC）Thenucleusdecaysbytransferringenergytoanorbitalelectron,whichisejectedinsteadoftherayConvers
15、ion electron4.Electroncapture(EC)Aprocessinwhichanorbitalelectroniscapturedbythenucleusandcombineswithaprotontoformaneutron.ECisalsocalledinverse decay.(EC,)decay125Idecayscheme5.+decay(Positrondecay)Aprotoninthenucleusistransformedintoaneutronandapositivelychargedelectron(positron).Thepositronandan
16、eutrinoareejectedfromthenucleus.p+n+e+energy15O的衰变AnnihilationofpositronAntiparticle(antimatter)ofanordinaryelectronAnnihilationreaction(Combineswithanelectron)MassconvertedintoenergyTwo0.511MeVannihilationphotonsOppositedirections(180Oapart).PET(PositronEmissionTomography)6.decayandNuclearFissionde
17、cayThenucleusejectsanparticle,whichconsistsoftwoneutronsandtwoprotons.NuclearfissionThespontaneousfragmentationofaveryheavynucleusintotwolighternuclei.Thelighternucleussharethenuclearmassinabouta60:40ratio.Question：Isthereadecay?Why?7.Typeofdecaysaccordingtotheiremittedparticlesray：decayray：-decay,+
18、decayray：（,）decay，（-,）decay，（+,）decay，IT，（EC，）Thoseemittingno,rays,butelectronsorXray：EC：CharacteristicXrayorAugerelectronsInternalconversion：Conversion electron, CharacteristicXrayorAugerelectronsIII.DecayofRadioactivity（I）Activityanditsunits1.Activity and its units, Specific activity,Radioactiveco
19、ncentrationActivity:Theactivityofaradioactivesampleistherateatwhichthenucleidisintegrate,ie.thenumberofdisintegrations/second(dps)ordpmUnitsS.I system: bequerel, Bq: 1 decay persecond=1BqTraditional：curie,Ci3.71010dps=1Ci Conversions1Ci=3.71010Bq1Bq0.2710-10Ci1mCi=10-3Ci=3.7107Bq1Ci=10-6Ci=10-3mCi=3
20、.7104Bq;1KBq=103Bq;1MBq=106Bq;1GBq=109BqRelatedterminologiesSpecificactivityActivityperunitmassofaradioactivesource.e.g.0.5Ci/gRadioactiveconcentrationTheactivityperunitvolumeofsolventinwhichtheradionuclideisdissolved,e.g.37MBq/ml,1mCi/ml)（II）RuleofExponentialThe changeof the number of radioactivenu
21、cleiand activity against time follow the rule ofexponential.N=N0e-tA=A0e-te-t:decayfactorN：numberofradioactivenucleiattimetA：activityattimetN0：numberofradioactivenucleiattimet=0A0：activityattimet=0:decayconstantDecayplotLinear:anexponentiallydecreasingcurveSemilogarithmic:astraightlinewhoseslopeisde
22、terminedbydecayconstant.(=0.1/s)Time（S）Relative number or activity Time（S）DecayplotLinearSemilogRelative number or activity（III）DecayConstant,Half-LifeandEffectiveHalf-Life1.DecayconstantTheproportionalityconstantbetweentherateofradioactivenucleardecayandthenumberofradioactivenucleiremaining. A=N e.
23、ge.g，assuming =0.02/s=2%/s,which means 2% of the assuming =0.02/s=2%/s,which means 2% of the radioactive nuclei decay in one second at any radioactive nuclei decay in one second at any moment, if N=10000moment, if N=10000，then A=0.02/s10000=200/s, then A=0.02/s10000=200/s, meaning 200 nuclei decayed
24、 in 1 second (on the meaning 200 nuclei decayed in 1 second (on the average). In the next second,?average). In the next second,?Decayconstant(cont)Each radionuclide has a characteristic valueIf a radionuclide has more than one mode of decay,(e.g 18F，97%+，3% EC），），with decay constant for each mode, 1
25、、2、3n，then the total decay constant is the sum, =1+2+3n2.Half-lifeThetimeittakesfortheactivitytofallbyhalf.e.g.,99mTcT1/2=6.02h，=0.693/6.02=0.115/h3.Effectivehalf-lifeThetimeittakesfortheactivitytofallbyhalfbecauseofthecombinedprocessesofphysicaldecayandbiologicalclearancePhysicaldecay:,T1/2Biologic
26、alclearance:b，Tbe=+bln2/Te=ln2/T1/2+ln2/TbEffectivehalf-lifeTe=T1/2Tb/(T1/2+Tb)Usually, T1/2 is known, Te can be measured, thus Tb determinedDetermine of exposureIV.InteractionofParticleswithMatter（I）InteractionsofChargedParticleswithMatter1.InteractionMechanisms:losingenergybyInteraction with orbit
27、al electron：Ionization,excitationInteractionwithnucleus:bremsstrahlung2.Specificionization()Totalnumberofionizations(ionpairs)perunitoftracklengthalongachargedparticletrackisrelatedtoparticlecharge(q),particlespeed(v)andmaterialdensitybyqve.g：particle（q，v）hasgreaterthanparticle,thushasgreaterionizat
28、ionpower.3AbsorptionAfterlosingenergychargeparticlesareabsorbedbymatter.particle:AtomofHelium- particle and the like: free electron ororbitalelectron+particle:annihilation（II）InteractionofRaysandX-rayswithMatter*Particle?Wave?Photon?Ray?Ionizingradiation?1.Photoelectriceffect(photoelectricabsorption
29、)A process in which an atom absorb the totalenergyofanincidentphotonThe photon disappearsThe energy is used to eject an orbital electron from the atom on a almost “inner first” baseLikelihood increases with increasing atomic number and decreasing photon energy ( Z3/E3)2.Comptoneffect(Comptonscatteri
30、ng)A collision between a photon and a outer shell orbital electron of an atom.transfers part of its energy to it, leaving the atom as the recoil electronThe photon is deflected through a scattering angle Aphoto-electroninteraction,notdependonthedensity,atomicnumberofthematerialMoreenergyislostwhenhi
31、ghenergyphotonsarescattered.e.g.80keV:upto24%140keV:upto36%360keV:upto58%Theenergytransferredtotherecoilelectronrangesfrom0(0)uptothemaximum(180o,backscattering)Thelowertheenergy,thelessthechangeinenergyforagivenscatteringanglePhotonenergyandscatteringangleWaysofseparatingscatteredradiation(1)Collim
32、atorWaysofseparatingscatteredradiation(2)Energy window3.ElectronPairProductionAninteractionwithanucleusinwhichthephotondisappears and its energy is used to create apositive-negativeelectronpair.Minimumphotonenergyis1.022MeV,whichistherestmassequivalentof2electrons.LikelihoodincreaseswithincreasingEa
33、ndZ(NouseinNM)4.DepositionofPhotonEnergyinMatterV.RadiationDetectorsinNM（I）Mechanisms1.IonizationCollectingtheionpairsIonizationchambers,Geiger-MllerCounters2.scintillationdetectionofthefluorescentradiationManyapplicationsinNM3.Darkeningofphotographicfilm4.Changoftemperature5.Chemicalchange（II）Gas-f
34、illeddetectors1.Ionizationofgase.g.34eVperionpairinairVoltageCurrentVoltageresponsecurve2.VoltageresponsecurveA:recombinationB:saturationIonizationchamberC:proportionalGasamplificationProportionalcounterD:limitedproportionalE:Geiger-MllerAvalancheofsecondaryionizationsGeiger-MllercounterF:continuesd
35、ischarge3.Dosecalibrator1.Basicallyanionizationchamber:Displaythesampleactivitybymeasuringthetotalcurrentresultingfrommultipleevents.Currentisproportionaltosampleactivity,normalizedforvariousradionuclidetodisplayactivity.Canmeasure“hot”samples(1Ci)4.Othergas-filleddetectorslProportionalcounterPartic
36、leenergylG-McounterCountingrate(countperunittime)AreasurveymeterslPocketdosimeterRecordsthetotalchargecollectedoveraperiodoftime（III）ScintillationDetector1. Scintillation *The number of photons of light emitted (intensity), is proportional to the energy of the incoming radiation. scintillation detec
37、tors can be used to determine the energy.2. Basic Composition and PrincipleScintillator: converts radiation energy to photons of visible light Photomultiplier tube: converts photons to electrons and multiplies the number of electronsOutput: A electrical pulse whose height is proportional to the amou
38、nt of radiation energy absorbed in the scintillator. 3.ScintillatorslPropertieslDensity and atomic numberlPhoto yield ( conversion efficiency)lScintillation decay timelNaI(Tl) ( Thallium-activated sodium iodide crystal)Usefulness Dense: =3.67g/cm3, Z=53 (iodine) Efficient: 30 eV per photon, or 13% c
39、onversion efficiency Adequate scintillation decay time: 230 nsecGood for penetrating radiations (X ray, ray)Disadvantages Fragile: sensitive to mechanical or thermal stress Hygroscopic: Hermetic sealing requiredOther scintillators BGO (Bi3Ge4O12) :for PET, =7.13g/cm3 , Scintillation decay time 300 n
40、sec LiquidGasNaI(Tl)BGO4.PhotomultipliertubeslComposition: photocathode, dynodes, anodelFunction: converts photons to electrons and multiplies the number of electronslPropertieslAmplification factorlHigh voltage5.SpectrumTheIdealPulse-HeightSpectrumPhotopeakCompton region (plateau) Compton edgeCompt
41、on valley Multiple Compton scatteringlTheActualSpectrumlBroadened peaklRounded edgelBackscatter peaklOther componentslBroadened peak and Rounded edge, Why? 300 eV per photoelectron from photocathode-Poisson- or Gaussian- shaped photopeakEnergyResolutionThewidthofpeak(E)measuredacrossitspointsofofhal
42、f-maximumamplitudeistheenergyresolution.Fullwidthathalfmaximum(FWHM)ofthephotopeakFWHM(%)=(E/E）*100%WhyFWHM?lResolutionv.senergylSpectrumv.sscintillatorsizeSpectrumv.sscatterE,morescatterE,easiertoseparatee.g.at90oscatteringanglePrimary，Scattered100keV,84keV500keV,253keV6.EnergyWindowApresetenergyra
43、ngeEnergy-Selective-counting,thusradionuclide-selective-countingDiscriminateagainstscatter,background,etc.outsidethedesiredenergyrange(Background?)7.LiquidScintillationCountersApplication：DetectinglowenergyraysFeaturesLiquid Scintillator(cocktail)Coincidence detection by two PMTs and coincidence cir
44、cuitVI.InstrumentationforRadiationDetection（I）BasicCompositionandPrincipleAn instrument for radiation detection is oftencomposedof:1. Radiation detector: converts radiation energy to electrical signals by collecting ion pairs, scintillation photons, etc. Probe:Detectors are often assembled with prim
45、ary electric circuit e.g. preamplifiers, to form a stand-alone component.2. Electronic instruments: amplifiers, pulse-height analyzers,scaler-timers, analog ratemeters.3. Ancillaries: sample servers, computers（II）ElectronicInstruments1.AmplifiersMatch（bypreamplifier）AmplificationShaping(Filtering:ba
46、nd-passfilter)2.Pulse-HeightAnalyzersFunction:Todeterminetheheightofpulse(1)Pulse-HeightDiscriminator(2)Single-ChannelAnalyzers(3)MultichannelAnalyzers(1).Pulse-HeightDiscriminatorComposition：OnevoltagecomparatorInput：PulsesofvariousheightOutput：PulsesofthesameamplitudeandshapeCondition：Theheightofa
47、inputpulseisabovethethresholdThreshold:apresettablevoltagelevelFunction：Totellifthepulse-height(thusenergy)isabovecertainvalue.(2).Single-ChannelAnalyzers(SCA)Composition：TwovoltagecomparatorsInput：PulsesofvariousheightOutput：PulsesofthesameamplitudeandshapeCondition：Theheightofainputpulseisbetweent
48、helowerthresholdandtheupperthresholdFunction：Totellifthepulse-height(thusenergy)iswithincertainrange.EnergyWindow(3).MultichannelAnalyzers(MCA)The core is an ADC: Analog- to-Digital Converter3.Scaler-TimerCountstheoutputpulsesfromPHAsinapresettime4.AnalogRatemetersDeterminestheaveragenumberofpulseso
49、ccurringperunitoftime（III）Applications1.Configurations2.InVitroMeasurementlNaI(Tl) well counterScintillator shape High detection efficiency 100% Geometric efficiency Low background by lead shielding lLiquid scintillation counterlDose calibratorlCompare晶体光电倍增管样品井型闪烁探测器3.InvivoMeasurementlMeasuring ra
50、ys from inside the bodylCollimatorsDesign: Cylindrical hole Expanding (conical) holeFunction: A passageway for rays from an area of interest lMultiprobesystemsLeadLeadDetectorUmbraPenumbraSingle-hole collimator（IV）NuclearCountingStatisticsFluctuationofcounts:Cause：DecayisaspontaneousprocessDistribut
51、ion： Gaussiandistribution(normaldistribution)whenN20Standard Deviation (SD) and Relative StandardDeviation(%SD)：forcountNSD=%SD=1/e.g.NSD%SD1001010%10,0001001%Conclusion:Largernumbersofcountshavesmallerpercentageuncertaintiesandarestatisticallymorereliablethansmallnumbersofcounts.Waystoreducetheeffe
52、ctoffluctuation:Longermeasuringtime(notoftenpracticable,e.g.decay)HigherdetectingefficiencyAlargerdoseLowerbackgroundcountingrateDataprocess,e.g.SmoothingandfilteringofcurvesandimagesCurvesmoothRawdataOne3-pointsmoothFive3-pointsmoothTwenty3-pointsmoothVII.Cameras（I）CompositionandprincipleCrystalPos
53、itionandEnergyCircuitsCollimatorDotDisplayand/orComputerInterfaceZYXPMTs and theirPreamplifiersCamera1.BasicPrinciple(1)Collimator:Projectingspacedistributiontothecrystalplane(2)CrystalandPMTarray:energyconverters.(3)PositionandEnergycircuits:Calculatingthepositionofthescintillationandtheenergyabsor
54、bed(4)DotDisplayand/orComputerInterface:Displayingaflashdotorsendingpositioncoordinatestocomputer2.CollimatorsCollimatorsTypesGeometric：Pinhole, Parallel hole, Diverging,ConvergingEnergy：Low energy, Medium energy, High energyResolution and Sensitivity Performance：All purpose, High resolution, High s
55、ensitivitye.g. LEAP (Low Energy All Purpose)3.CrystalandPMTarrayCircularorrectangularNaI(Tl)crystalThickercrystalmakeshigherdetectionsensitivityThinnercrystalmakesbetterspaceresolutionMorePMTsmakebetterspaceresolutionTheoutputofeachPMTsimultaneouslyfeedstoX,YandZchanneltoprocessRectangularPMTarrayfr
56、omGE4.PositionandEnergyCircuitslEnergy-independent positioning signal: Centroid of scintillationlEnergy-selective imaging: Multichannel AnalyzerXiYYiX0AxiandAyiaretheweightsoftheithPMT,Axi=kXi;Ayi=kYi.IiistheintensityofscintillationreceivedbyithPMTkisacommonproportionalfactorwhichisfinallycanceledou
57、tinXandY5.ImageRecordinglOnesetof(X,Y,Z)signalisgeneratedforeachandeveryvalidevent.lOne flash dot is displayed for one valid eventlOr one set of (X, Y) value is converted to digitslRecordingmanyeventsmakesaimagelPolaroid camera or 35-mm cameralComputer display(II)ComputersinNM1. PrinciplereviewHardw
58、aresTangible PartsCPUMemoryDiskSoftwaresContainingInstructionsDataOperating System SoftwaresApplication Softwares2. ComputerInterfaceComputers Communication Channel with Imaging DevicesGamma CameraSPECTPETOutput From ComputerAcquisition InstructionsDigital to Analog Conversion (DAC)Input From Imagin
59、g DeviceImagesAnalog to Digital Conversion (ADC)(T,Xd,Yd,R).(T,Xd,Yd)(T,3.ImageCreationFrameModeListModeRadio-pharmaceuticalsMatrixPixel (Picture Element)RadioactivityBrightness or Color versus RadioactivityFunctional ImageCellular Level Organ Function3.ImageCreation(cont)4.Image Storage and Transmi
60、ssionImages Stored as Computer FilesPublic Format (JPEG, GIF)Inter (Only in Nuclear Medicine)DICOM Standard Format (All Medical Images)Manufacturers Proprietary FormatsImage Computer NetworksFTP ( Protocol)Web Based Upload/DownloadPACS (Picture Archiving and Communication System)BenefitsLong Term St
61、orageTelemedicine(III)GammaCameraApplications1.MatrixSizeandImageModeLargermatrixcanbetterpreservetheimageresolution.Typical: 128128, 6464Pixel Size: 3mm, 6mmImagemodeisdeterminedbypixeldepthByte Mode: 1 byte/pixel Maximum counts/pixel=255 Word Mode: 1 word/pixel Maximum counts/pixel=655352.StaticAc
62、quisitionPurposeDemonstrating the Size and Position of an OrganThe Distribution of Function within the organAcquisitionParameters128128, Word Mode, Counts/frame or Time/frameAlsocalledImage sequenceCountmatters-50k500k2.DynamicAcquisitionPurposeAseriesofimagestotrackthechangeofradiopharmaceuticaldis
63、tributionAcquisitionParameters6464or128128,bytemodeorwordmodeNumberofgroups,Numberofframesinagroup,Time/frameinthegroups,Pausebetweengroups2.DynamicAcquisition(cont)DynamicImageDisplayMultipleframesCinematic3.WholeBodyScanMethodContinuous move of camera head or bed Step and shootAcquisition Paramete
64、rsSpeed, Time, (Matrix size) 4.MultigatedAcquisitionMethodR wave of ECG is used as a triggerA cardiac cycle is divided into 16 to 24 frameThe corresponding frames are added to form one frame Cycle1Cycle21324561324561324564.MultigatedAcquisition(cont)AcquisitionParametersMatrixsizeandImagemodeFrames/
65、Cycle,Totalcounts,time,ornumberofbeats5.ImageProcessinglDigital ImagelMatrix and pixellPixel and CountslRegion of Interest (ROI) AnalysislTotal Counts, Number of Pixel, Average CountslTime-Activity CurveslImage MathlImage FilteringSpatialDomainandFrequencyDomainThey are Equal and interchangeable via
66、 Fourier TransformationWhat should we look at in frequency domain?SpatialDomainFrequencyDomainFTSpatialdomainandfrequencydomain(cont)Spatial domain: Amplitude and positionFrequency domain: Amplitude and frequencyLarger size in spatial domain has lower frequency in frequency domain and V.VSpatialdoma
67、inandfrequencydomain(cont)Image filtering: Modification of amplitude in frequency domainBasic Types of Filter：Lowpass, Bandpass, HighpassCut-offfrequencyVIII.SPECT(Single-Photon Emission (Single-Photon Emission Computed Tomograph)Computed Tomograph)(I)BasicCompositionCamerawithimprovedperformance:un
68、iformity,linearityRotatingGantryandLow-AttenuationbedComputerandSPECTsoftware(II)Principles1. Projection and TomographyProjection:ascount,proview180oor360oProjectionsReconstruction:Projection-TomographSectionProfileView(s)2. Reconstruction by BackprojectionlHow to dolProblemlStar artifactlCause of p
69、roblemlBackprojection causes reciprocal filteringAA=1/fFrequency3.ReconstructionbyFilteredBackprojectionRampFilterAA=1/fFrequencyFrequencyA1/fxf=1AFrequencyRampFilter(A=f)4.WindowFilterPurpose:Reducenoise0.5100.51FrequencyAmplitudeA.RampFilter10.500.51FrequencyAmplitudeB.WindowedRamp4.WindowFilter(c
70、ont)Parameters:cut-offfrequencyandorder5.ReconstructionSteps6.AttenuationandScatterCorrectionBeforeAfter（III）ApplicationsPlanar (Projection) Tomograph1.Purpose：Bettercontrast（Resolution improvement is limited）2.AcquisitionandReconstructionParametersAcquisitionArcofAcquisition,MatrixSize,NumberofView
71、s,TimeorCountperviewReconstructionWindowFilterType,Cut-offFrequency,Order3.ImageDisplayImageReformatting3DVolumeDisplay（IV）QualityControlofCameraandSPECT1.QualityAssuranceAlleffortsmadetoachieveideal,error-and-artifacts-freeoutcome2.QualityControlofNMInstrumentsPerformanceTestsTo verify the usefulne
72、ssCorrectionorCalibration To improve performance by modifying some quantities3. Performance CharacteristicsTypesIntrinsic Performance: Collimator offSystem (extrinsic) Performance: Collimator on Linearity, Uniformity, Spatial ResolutionTrueDistributionBarrelDistortionPincushionDistortionImageoffour-
73、quadrantbarphantomGoodUniformityBadUniformity4.Corrections：UniformityCorrection，CenterofRotationCorrectionSinogramXProjectionAngleyx1/0.90.915.TotalPerformanceOptimization(BestCondition)Performance5.TotalPerformance(cont)ClinicalConditionPerformanceAnthropomorphicthoraxphantomCardiacinsert.PET(Posit
74、ronEmissionTomograph)1.CoincidenceDetectionLOR: Line of ResponseMore Effective, Better Spatial ResolutionCoincidenceDetection2.ProjectionAcquisitionandImageReconstructionTrue coincidence events are recordedAngular projections formed by regrouping events Images are reconstructed by Filtered Backprojection, etc.DualHeadAcqRingDetectorAcqRegroupingProjectionbyRegroupingX.DevelopmentofNuclearMedicineInstrumentsThankYou！
