EMI Scanner

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Early Days of CT: Innovations (Both Good and Bad) Robert G. Gould Department of Radiology University of California San Francisco

description

EMI scanner Innovation

Transcript of EMI Scanner

  • Early Days of CT: Innovations (Both Good and Bad)

    RobertG.Gould

    DepartmentofRadiology

    UniversityofCaliforniaSanFrancisco

  • The Names: An Incomplete List

    JohannKarlAugustRadon18871956 WilliamHenryOldendorf19251992 AllanMcLeodCormack19192004 GodfreyNewboldHounsfield19192004 RobertLedley1924

  • Sir Godfrey Hounsfield

    ElectedtoRoyalSociety1975

    Nobelprize1979sharedwithAllanCormack

    19192004

  • EMI Head Scanner

    Firstclinicalimage(AtkinsonMorleyHospitalLondon

  • EMI Head Scanner

    1972salesbrochure

    Doseinformation

  • EMI Head Scanner

    XRayControls

    Geometry: Translaterotate,pencilbeam

    Scantime: 4.520min

    RotationAngle: 1

    Numberofviews: 180

    Samplesperview: 160

    Totalsamples: 28,800

    Matrix: 80x80

    FOV: 23.5cm

    Pixelsize: 3x3mm

    Slicethickness: 13mmor8mm

    Xraytube: Fixedanode

    TechniqueFactors: 100(40),120(32),140(27)[KVp(mA)]

    Detectors: NaIPMT

    Cost: ~$350,000

  • Question: What machine was the first multislice CT?

    Answer:EMIheadscanner!Ithad2detectorsalongtheZaxis.

  • EMI Head Scanner

    Printoutscale+ 500

    1972salesbrochure

    Firsttrulydigitaldeviceinradiology

  • EMI Head Scanner

    1972salesbrochure

  • EMI: Rise and Fall1971: PrototypeheadscannerinstalledatAtkinson

    MorleyHospital1972: FirstclinicalresultspresentedbyJamesAmbrose,

    MDon70patients1973: Clinicalproduction,twounitsinstalledintheUSat

    MayoClinicandatMGH1974: ACTAwholebodyscannerinstalled1975: 3rdgenerationmachinesinstalled1975: 10companiesnowmakeCTscannersincludingall

    ofthemajorequipmentmanufacturers1978: EMIloses$56million1979: EMIintroducesthe7070nutating ringscanner1979: EMIsellsbusinesstoThornElectricalIndustries1980: GEbuysscannerbusinessfromThornfor$37.5

    million

  • EMI: Rise and Fall

    ThesagaofEMIs CTscannerbusinessbecameacasestudyattheHarvardBusinessSchool: AlthoughCTrepresentedaconceptualbreakthrough,thetechnologiesitharnessedwerequitewellknownandunderstood

    Supposedlywellprotectedbyawallofpatents Oncetheproductwasonthemarketitcouldbereverseengineeredanditsessentialfeaturescopies

  • Whole Body Scanner ACTAScanner

    InstalledinGeorgetownUniversityMedicalCenterinFebruary1974

    Ist generationgeometryverysimilartoEMIheadscanner

    5minutedataacquisitiontime DevelopedbyRobertLedley SoldbyPfizer Soldforunder$300,000 CurrentlyintheSmithsonian

    NationalMuseumofAmericanHistory

  • Delta Scanner (Ohio Nuclear) 1st installedNovember1974intheClevelandClinic

    Wholebodyscannerwithtranslaterotategeometrywith~2minuteacquisition

    Producedoneofthefirst2nd generationscanners 3detectorconfiguration

    Subsequentlyproduced3rd and4th generationscanners

    Relativelylonglived(19741985) BoughtbyJohnsonandJohnson

    IntellectualpropertysoldtoGEin1986

  • CT Data Acquisition

    Calibratedetectorspriortoacquiringeachview

    X-ray tubecollimator

    detectortranslate

    rotate 1o

    X-ray tube

    detectors

    collimator

    translate

    rotatefan angle

    Translaterotate(1st generation)

    Translaterotate,fanbeam(2nd generation)

  • CT Geometries

    X-ray tubecollimator

    detectors

    Rotaterotate(3rdgeneration)

    detectors

    collimator

    Rotatestationary(4thgeneration)

    X-ray tube

  • Quest for Scan Speed

    1000

    100

    10

    1

    0.1

    0.011975 1980 1985 1990 1995 2000

    Year

    Scan

    time(sec)

    2005 2010

  • Typical Performance Circa 1976 SearlePho/Trax

    Headscanner 3rd generation Gasdetectors 540secscantime 40secrecon Alsohadabodyscanner(Pho/Trax4000

  • Innovations in 3rd Generation Geometries

    Challengewastohavestabledetectors Noabilitytocalibrateduringacquisition Somemachinerequiredcalibrationbetweenpatients

    Samplesperviewdeterminedbydetectorgeometry

  • Gas Detectors

    HighpressureXe ~20atm ~1020cmthick

    Usedonlyin3rd generationmachines GE,Varian,Artronix,Searle

  • Sampling Innovations: 3rd Generation

    Quarteroffset(1979)

    RABrooks,etalJComputAssistTomo3(1979)511518

    FlyingSpot(1981)

  • American Science and Engineering First4th generationCT(1976) RightslatersoldtoPicker

    UsedBGO Developedtoovercomestabilityrequirementsof3rd generationgeometry

    Shownat1976RSNA

  • Innovations in 4th Generation Geometries

    Challengeistohavesufficientviews Samplesperviewnotanissue

  • EMI 7070

    4th generation,nutating ring Reducesringdiameter

    Foragivennumberofdetectors,improvesspatialresolution 1088CsI detectors

    Circalate1970s

    x

    x

  • Artronix: A Typical Case EnteredtheCTmarket~1974 3rd generation

    Madebothheadandbodyscanners

    OneofthefirstsystemsusingXe gasdetectors

    Produceda4th generationvariant

    Wentoutofbusinessin1978

  • Decisions

  • Miscellaneous Innovations

    Company Innovation

    AS&E 4th generationgeometry,BGOdetector

    Artronix Xe detector,4th generationvariant

    Elscint Combined2nd/3rd generationmachine

    OhioNuclear 2nd generation,CaF2(Eu)solidstatedetector

    Varian Xe/Krgasdetector,highvoltagesliprings

  • 1978 Status

    14companieslisted

    Allgeometriesrepresented

    PolicyImplicationsofComputedTomography(CT)Scanner,NTIS#PB81163917(1978)

  • CT Industrial Applications (NDT)

    AerojetStrategicPropulsionCompany Principleusesolidfuelrockets/missles

    420KeV Upto1mdiameterobjects

    Slicethickness110mm

    1981

  • TeletomographyReconstructiondonecentrally

    Dataacquisitionanddisplayonly

    Modemlinks

    MastergantryRemotegantry

    RemoteDisplay

    Circa1985

  • Dose Measurements

    ComputedTomographyDoseIndex formalizedin1981byTBShope,etalMedPhys8(1981)488495.

    CTDI14T =1

    nTD(z)dz

    7T

    +7T

    Index

  • Socioeconomics

    Requirededucation(reeducation?)ofpracticingradiologists

    Costeffectivenessquestions ConcernsregardingthecostofmedicalcareifCTdidnotreplaceexistingprocedures

    MuchworkremainstobedoneinordertoestablishthoseareasinwhichCTscanningwillactuallyaffectpatientmanagementnotjustverifytheexistenceofdisease! McCulloughandPayne:XRayTransmissionComputedTomography,MedPhys4(1977)8598.

  • And Today

    Scantimes$2.5million

    Early Days of CT: Innovations (Both Good and Bad)The Names: An Incomplete ListSir Godfrey HounsfieldEMI Head ScannerEMI Head ScannerEMI Head ScannerQuestion: What machine was the first multislice CT? EMI Head ScannerEMI Head ScannerEMI: Rise and FallEMI: Rise and FallWhole Body ScannerDelta Scanner (Ohio Nuclear)CT Data AcquisitionCT GeometriesQuest for Scan SpeedTypical Performance Circa 1976Innovations in 3rd Generation GeometriesGas DetectorsSampling Innovations: 3rd GenerationAmerican Science and EngineeringInnovations in 4th Generation GeometriesEMI 7070Artronix: A Typical CaseDecisionsMiscellaneous Innovations1978 StatusCT Industrial Applications (NDT)TeletomographyDose MeasurementsSocioeconomicsAnd Today