Download - EMI Scanner
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Early Days of CT: Innovations (Both Good and Bad)
RobertG.Gould
DepartmentofRadiology
UniversityofCaliforniaSanFrancisco
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The Names: An Incomplete List
JohannKarlAugustRadon18871956 WilliamHenryOldendorf19251992 AllanMcLeodCormack19192004 GodfreyNewboldHounsfield19192004 RobertLedley1924
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Sir Godfrey Hounsfield
ElectedtoRoyalSociety1975
Nobelprize1979sharedwithAllanCormack
19192004
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EMI Head Scanner
Firstclinicalimage(AtkinsonMorleyHospitalLondon
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EMI Head Scanner
1972salesbrochure
Doseinformation
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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
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Question: What machine was the first multislice CT?
Answer:EMIheadscanner!Ithad2detectorsalongtheZaxis.
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EMI Head Scanner
Printoutscale+ 500
1972salesbrochure
Firsttrulydigitaldeviceinradiology
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EMI Head Scanner
1972salesbrochure
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EMI: Rise and Fall1971: PrototypeheadscannerinstalledatAtkinson
MorleyHospital1972: FirstclinicalresultspresentedbyJamesAmbrose,
MDon70patients1973: Clinicalproduction,twounitsinstalledintheUSat
MayoClinicandatMGH1974: ACTAwholebodyscannerinstalled1975: 3rdgenerationmachinesinstalled1975: 10companiesnowmakeCTscannersincludingall
ofthemajorequipmentmanufacturers1978: EMIloses$56million1979: EMIintroducesthe7070nutating ringscanner1979: EMIsellsbusinesstoThornElectricalIndustries1980: GEbuysscannerbusinessfromThornfor$37.5
million
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EMI: Rise and Fall
ThesagaofEMIs CTscannerbusinessbecameacasestudyattheHarvardBusinessSchool: AlthoughCTrepresentedaconceptualbreakthrough,thetechnologiesitharnessedwerequitewellknownandunderstood
Supposedlywellprotectedbyawallofpatents Oncetheproductwasonthemarketitcouldbereverseengineeredanditsessentialfeaturescopies
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Whole Body Scanner ACTAScanner
InstalledinGeorgetownUniversityMedicalCenterinFebruary1974
Ist generationgeometryverysimilartoEMIheadscanner
5minutedataacquisitiontime DevelopedbyRobertLedley SoldbyPfizer Soldforunder$300,000 CurrentlyintheSmithsonian
NationalMuseumofAmericanHistory
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Delta Scanner (Ohio Nuclear) 1st installedNovember1974intheClevelandClinic
Wholebodyscannerwithtranslaterotategeometrywith~2minuteacquisition
Producedoneofthefirst2nd generationscanners 3detectorconfiguration
Subsequentlyproduced3rd and4th generationscanners
Relativelylonglived(19741985) BoughtbyJohnsonandJohnson
IntellectualpropertysoldtoGEin1986
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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)
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CT Geometries
X-ray tubecollimator
detectors
Rotaterotate(3rdgeneration)
detectors
collimator
Rotatestationary(4thgeneration)
X-ray tube
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Quest for Scan Speed
1000
100
10
1
0.1
0.011975 1980 1985 1990 1995 2000
Year
Scan
time(sec)
2005 2010
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Typical Performance Circa 1976 SearlePho/Trax
Headscanner 3rd generation Gasdetectors 540secscantime 40secrecon Alsohadabodyscanner(Pho/Trax4000
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Innovations in 3rd Generation Geometries
Challengewastohavestabledetectors Noabilitytocalibrateduringacquisition Somemachinerequiredcalibrationbetweenpatients
Samplesperviewdeterminedbydetectorgeometry
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Gas Detectors
HighpressureXe ~20atm ~1020cmthick
Usedonlyin3rd generationmachines GE,Varian,Artronix,Searle
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Sampling Innovations: 3rd Generation
Quarteroffset(1979)
RABrooks,etalJComputAssistTomo3(1979)511518
FlyingSpot(1981)
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American Science and Engineering First4th generationCT(1976) RightslatersoldtoPicker
UsedBGO Developedtoovercomestabilityrequirementsof3rd generationgeometry
Shownat1976RSNA
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Innovations in 4th Generation Geometries
Challengeistohavesufficientviews Samplesperviewnotanissue
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EMI 7070
4th generation,nutating ring Reducesringdiameter
Foragivennumberofdetectors,improvesspatialresolution 1088CsI detectors
Circalate1970s
x
x
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Artronix: A Typical Case EnteredtheCTmarket~1974 3rd generation
Madebothheadandbodyscanners
OneofthefirstsystemsusingXe gasdetectors
Produceda4th generationvariant
Wentoutofbusinessin1978
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Decisions
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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
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1978 Status
14companieslisted
Allgeometriesrepresented
PolicyImplicationsofComputedTomography(CT)Scanner,NTIS#PB81163917(1978)
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CT Industrial Applications (NDT)
AerojetStrategicPropulsionCompany Principleusesolidfuelrockets/missles
420KeV Upto1mdiameterobjects
Slicethickness110mm
1981
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TeletomographyReconstructiondonecentrally
Dataacquisitionanddisplayonly
Modemlinks
MastergantryRemotegantry
RemoteDisplay
Circa1985
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Dose Measurements
ComputedTomographyDoseIndex formalizedin1981byTBShope,etalMedPhys8(1981)488495.
CTDI14T =1
nTD(z)dz
7T
+7T
Index
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Socioeconomics
Requirededucation(reeducation?)ofpracticingradiologists
Costeffectivenessquestions ConcernsregardingthecostofmedicalcareifCTdidnotreplaceexistingprocedures
MuchworkremainstobedoneinordertoestablishthoseareasinwhichCTscanningwillactuallyaffectpatientmanagementnotjustverifytheexistenceofdisease! McCulloughandPayne:XRayTransmissionComputedTomography,MedPhys4(1977)8598.
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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