QC Protocols Gamma Camera & SPECT Systems

1 QC ProtocolsQC ProtocolsGamma Camera & Gamma Camera & SPECT SystemsSPECT SystemsJames R Halama, PhDJames R Halama, PhDLoyola University Medical CenterLoyola University Medical CenterMaywood, ILMaywood, Camera ImagingGamma Camera overview of Gamma Camera OperationBrief overview of Gamma Camera overview of Camera CalibrationsBrief overview of Camera PhantomImagingSPECT &ReconstructionAcquisition & &ICANL Accreditation RequirementsACR &ICANL Accreditation RecommendationsFinal RecommendationsGamma Camera Imaging ofRadioactive Sources in PatientsThree major channels the -rays and localizes thesource in the (Tl) Crystal(single ormulti-crystal) over width ofpatient stops the ofPMT s localizes -ray interaction in crystalCollimatorPMTPMTNaICrystalLocaliz e -ray Hit in Crystal byPosition Weighed Sumof PMTP ulsesFigure 4 Figure 4--22P2P1P3P4P5P6P7P8p1p2p3p4p5p6p7p8r1r 2r3r4r5r6r7r8Xp1r1+ p2r2+.. +p7r7+p8r8p1+p2+.

2 +p7+p8X =X+ SummingAmplifierpi-PMTipulseri-positiona l weightNaI crystalComponents of Gamma CameraSpatial ResolutionnnIntrinsicIntrinsicResolution Resolution Ability ofAbility ofthetheNaI(NaI(TlTl) crystal and PMT) crystal and PMTcombination to localizecombination to localize --rayrayinteractions in the in the Ability ofAbility ofthe collimator to localize thethe collimator to localize the --ray source in the source in the OverallOverallresolution combining collimatorresolution combining collimatorand intrinsic factors. Totaland intrinsic factors. Totalresolution is quadratic sumofresolution is quadratic sumofthe twothe ResolutionFWHMC dLtcfc(l+f+c)dld hole diameterl hole lengtht septal thickness of leadf collimator to sourcedistancec collimator to crystalcenterdistanceCollimator Ratio Resolving power of collimatorSource to CrystalDistancelAvailable CollimatorsCollimatorTypeHoleDiameter(mm )HoleLength(mm)FWHMat 0 cm(mm)**FWHMat 10 cm(mm)**FWHMat 20 cm(mm)**Sensitivity(CPM/ Ci)Low Energy AllPurpose (LEAPor GAP) (99mTc)Low EnergyHigh (99mTc)Low (99mTc) (67Ga)High (131I) ~ (18F)** Siemens Orbiter Gamma Camera Systemwith intrinsic resolutionof mmFWHMG amma Camera Quality ControlGamma Camera Quality ControlnnBasic Planar QC ProceduresBasic Planar QC ProceduresIntrinsic Spatial ResolutionMeasurementGammaCamera99mTc Point Source(400 800uCi)

3 4-Quad Bar Phantom4-Quadrant barphantomreplacesthe collimator The image is theshadow of the leadbars on the PhantomCollimatorExtrinsic Spatial ResolutionMeasurementPlanar FloodSource(10mCi99mTc or57Co)Planar Sheet Sources57 CoShhetSource T1/2270 days; 122keV ; 10-15mCiat time Sheet Source(water filled) T1/26hrs.; 140keV ; 10-15mCiat time of Spatial Linearity withPLES PhantomImages of PLES (parallel line equal spacing)phantomwith99mTc sourceDeviation fromstraight line ofless than Linearity with 4-Quadrant Bar PhantomNotewavey/curve-linear appearanceof lead barsthroughout Intrinsic UniformityGammaCameraPoint Source400-800 uCi5 UFOVD iameterdistance5-15 Million Counts1-3 Packing(higher sensitivity)at edgeStatistical Variation: 3 Mcts. ~ 1600 ct/cm2(+ ) 15 Mcts. ~ 4800 ct/cm2(+ )No CollimatorFlood ImageMeasuring Extrinsic UniformityGammaCameraCollimatorPlanar SheetSource10-15mCiof57Co or99mTc5-15 Million Counts3-15 Packingshielded bycollimator Camera CalibrationsGamma Camera GainsPMT GainBy FSEPMT &Energy CalibrationsPMT &Energy CalibrationsSecondEnergyCorrectionBy FSEL inearity &UniformityLinearity &UniformityCalibrationsCalibrationsThird LinearityCorrectionBy FSEF ourthUniformityCorrectionBy Control PracticesQuality Control Daily ensure isotope energy level centered images of 5-15 million counts each day ofuse, before imaging )Extrinsic flood image is preferred and tests heavily )Intrinsic flood image to test detector only, especially atthe periphery of the FOV.

4 Acquired at least one (preferred) or extrinsic images of 5-10million counts of four-quadrant bar phantomonce per (preferred) or extrinsic images of 5-10million counts with PLES or four-quadrant bar phantomonce per Correction Matrix Corrects residual non-uniformities. Flood images of 100 Mctsonce per month foreach isotope FloodsDaily FloodsPlot IU for UFOV or CFOV dailyPrePre--Assigned Action LevelsAssigned Action no further evaluation repeat flood once; if still marginal next day/week contact Physicistor supervisorto determine status; a re-calibration may be repeat flood once; if still unacceptable contact Physicistorsupervisorto determine status; a re-calibration may be necessaryGamma CameraIntrinsic Uniformity IUin UFOVE xtrinsic Uniformity IUin UFOVV ertexI below above below above II below above below above III below above below above IIII rregradless of IU, if a single tube is visiblein the flood image,contact Physicistor supervisortodetermine and/or Extrinsic Floods?

5 Intrinsic and/or Extrinsic Floods?Det2 Co-57 Det2-Tc-99mDet1 Co-57 Det1 Tc-99mRoutine Bar Pattern ImagesRoutine Bar Pattern Images Why?Why? mm90 Deg. RotationIntrinsic and/or Extrinsic Bars?Intrinsic and/or Extrinsic Bars? mmIntrinsic BarsIntrinsic Bars Better Assess X/YBetter Assess mmIntrinsic BarsIntrinsic Bars Better AssessBetter AssessLinearityLinearityNote wavy barswrapped aroundPMT sRotating Gamma Camera SPECTR otating Gamma Camera SPECTSPECT AcquisitionWhole Body Planar BoneBone SPECT 256x1024 image 20 min. million counts 120 128x128images 3ostep &shootrotation over360o 30sec/image/head 32 min. totalacq. 60,000cts/imageReconstructed Bone SPECT ImagesReconstructed Bone SPECT ImagesEach line across the imagecorresponds to onetransaxial slice in thetomographic volume. 4 mmslice thickness for 128matrix over 50 vs. Iterative ReconstructionsIterative-OSEMFBPG amma Camera SPECT QCGamma Camera SPECT QCnnUniformity CorrectionsUniformity CorrectionsnnCOR CorrectionsCOR CorrectionsnnSPECT PhantomImagingSPECT PhantomImagingConcentric rings of alternating high and lowcount densities appear in the transaxial imagesdue to insufficient Gamma Camera Ring ArtifactBullseye Ring ArtifactUniformity CorrectionUniformity CorrectionAcquire High CountFlood ImageGenerate FloodCorrection Matrix30-100 million count flood images.

6 10 times daily flood requirementsUniformity Correction is aUniformity Correction is aCalibrationCalibration Uniformity correction appliedto all patient images Both planar and SPECT imagingIntrinsic Uniformity CalibrationIntrinsic Uniformity for TcPerformed for Tc--99mand/or other99mand/or otherisotope used clinicallyisotope used point sourcePrecise point background and scatter freeLow background and scatter count rateCorrect count total countsCorrect total MANUALFOLLOWTHE MANUALF ractured Point Sources?Fractured Point Sources? Isotope in ml in hub ofsyringe or in end of the needle cap. Requires exchange of needle. Do not mishandle and this be used?Can this be used?Acquired at 100 KcpsIntrinsic Uniformity Correction May Mask Underlying Problems!Detector with intrinsic linearity problemsExtrinsic Uniformity CalibrationExtrinsic Uniformity the bestIdeally the best--Corrects for bothCorrects for bothcollimator and intrinsic detectorcollimator and intrinsic planar flood sourceRequires planar flood TcIdeally Tc--99m, Co99m, Co--57 is only a surrogate57 is only a for each collimatorRequired for each MANUALFOLLOWTHE MANUALE xtrinsic Uniformity Correction May Mask Collimator Problems!

7 Damaged collimator with crushed lead septaExtrinsic or Intrinsic Correction?Co-57 ExtrinsicTc-99mIntrinsicSPECT Center-of-RotationThe center ofthe gammacamera in allacquiredimages must beknownSPECTSPECTCOR Acquisition is a CalibrationCOR Acquisition is a to correct patient imagesUsed to correct patient calibration for both 180 and 90 degreeExtrinsic calibration for both 180 and 90 degreedetector separationsdetector follow manufacturer recommendationsMust follow manufacturer recommendationsregarding number and placement of sourcesregarding number and placement of must have sufficient activitySources must have sufficient monthly, or per manufacturerCompleted monthly, or per manufacturerspecificationsspecifications JaszczakPhantom:Cold Rods: , , , , , mmCold Spheres: , , , , , mmSPECT PhantomImagingSPECT PhantomImagingACR SPECT PhantomPlanar Extrinsic Spatial ResolutionPlanar Images 500 K5000 smallest rod sections count rates for multiple detectors , mustbe within 5%of one another (remember to decaycorrect for Tc-99m) SPECT phantomstudies with 2-3 timescounts obtained clinically (24 million for ACR).

8 At highest resolution filter. Use FBPfor PhantomImaging ProtocolSPECT PhantomImaging Protocol Look for bullseyeartifacts. If present,new intrinsiccorrection floodmust be acquired. Spatial resolution number of rodsections observed. Contrast numberof PhantomSPECT PhantomImagesImages180 Degree Orbit SPECT180 Degree Orbit SPECTSPECT PhantomAcquisitions for dualhead SPECT systemoffixed heads and 180degree acquisition Problems!Uniformity Problems!PhantomReconstruction no ACPhantomReconstruction no ACPhantomReconstruction &ACPhantomReconstruction &ACACR SPECT PhantomFormattingSumming of SlicesUniformity(3 slices)Resolution(12 slices)Contrast(2 slices)NonNon--Aligned detectors in XAligned detectors in XSinogramNonNon--Aligned detectors in YAligned detectors in YLinogramACR QC GuidelinesACR QC Guidelines or SystemUniformity-each day of or SystemSpatial Multiple Detector RegistrationCalibration/Test for SPECT Floods For Uniformity Correctionfor SPECTS ystems-frequency as recommended by a qualified SystemPerformance for SPECT Systems quarterlySPECT Phantom; Tc-99mmust be done at least semiannually.

9 Otherradionuclidesmay be tested on alternate Nuclear Medicine/PET Accreditation ProgramRequirements 3/28/2008 ACR QC GuidelinesACR QC Guidelines Annual TestsAnnual TestsACR Nuclear Medicine/PET Accreditation ProgramRequirements 3/28 or SystemSpatial all that count rate per unit activity is Rate SystemPerformance for SPECT Systems QC GuidelinesICANL QC peaking-Daily prior to use; documentation notrequired) or extrinsic uniformity-Daily prior to use;(approximately 2-5 million counts) and linearity Weekly bar calibration-Monthly or per manufacturer of rotation( SPECT ) maintenance-Every 6 monthsThe ICANL Standards for Nuclear Cardiology, Nuclear Medicine andPET Accreditation, 2007 Recommended QC GuidelinesRecommended QC peakingEnergy peaking--Daily prior to useDaily prior to or extrinsic uniformityIntrinsic or extrinsic uniformity--Daily prior to use; (4 Daily prior to use; (4--1010million counts)million counts) CalibrationUniformity Calibration--Monthly, or per manufacturer sMonthly, or per manufacturer srecommendations: only when necessaryonly when uniformity, resolution and linearity QCIntrinsic uniformity, resolution and linearity QC Center of rotationSPECT Center of rotation Monthly, or per manufacturer sMonthly, or per manufacturer PhantomSPECT Phantom(quarterly)(quarterly) maintenancePreventive maintenance semisemi--annual by FSEannual by FSER ecommendedRecommended SPECT PhantomImagingSPECT intrinsic and collimator uniformity,Assesses intrinsic and collimator uniformity,altogether.

10 If only Tcaltogether. If only Tc--99mintrinsic uniformity99mintrinsic uniformitycorrection is applied and not ring artifactscorrection is applied and not ring artifacts nonocollimator flood correction is flood correction is sensitivity differences in detectorsAssesses sensitivity differences in adequacy of COR corrections observedAssesses adequacy of COR corrections overall SPECT resolution and contrastAssesses overall SPECT resolution and contrastRecommendedRecommended QC Guidelines AnnuallyQC Guidelines uniformity, spatial resolution, & all that count rate per unit activity per detector energy rate SPECT performance SPECT Phantomand possiblyfor additional display&systeminterlocks