outline the challenges of ct accreditation: introduction · siemens sensation 10 important notes:...

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The Challenges of CTThe Challenges of CTAccreditation:Accreditation:IntroductionIntroduction

Thomas G. Ruckdeschel, MS, DABRThomas G. Ruckdeschel, MS, DABRDiagnostic Radiological PhysicistDiagnostic Radiological Physicist

Medical Nuclear PhysicistMedical Nuclear PhysicistAlliance Medical Physics LLCAlliance Medical Physics LLC

OutlineOutline

�� AcknowledgementsAcknowledgements�� ResourcesResources�� Common Reasons for FailureCommon Reasons for Failure�� ACR Accreditation: Table IACR Accreditation: Table I�� GE ScannersGE Scanners�� Siemens ScannersSiemens Scanners�� Philips ScannersPhilips Scanners�� Toshiba ScannersToshiba Scanners�� Electronic SubmissionElectronic Submission�� Panel DiscussionPanel Discussion

DisclaimerDisclaimer

�� ACR CT Accreditation PhysicsACR CT Accreditation PhysicsSubcommitteeSubcommittee•• Charter memberCharter member

•• ReviewerReviewer

�� Alliance Medical Physics LLCAlliance Medical Physics LLC•• PresidentPresident

•• Medical Physics ConsultantMedical Physics Consultant

AcknowledgementsAcknowledgements

�� ACR CT Accreditation Physics SubcommitteeACR CT Accreditation Physics Subcommittee•• Dianna Cody, PhD CoDianna Cody, PhD Co--ChairChair•• Doug Pfeiffer, MS CoDoug Pfeiffer, MS Co--ChairChair•• CynthiaCynthia McColloughMcCollough, PhD, PhD

�� Former ChairFormer Chair

•• MichaelMichael McNittMcNitt--Gray, PhDGray, PhD•• Thomas Payne, PhDThomas Payne, PhD

�� ACR StaffACR Staff•• Theresa BranhamTheresa Branham•• Dina HernandezDina Hernandez•• Krista BushKrista Bush

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�� GE HealthcareGE Healthcare

�� Siemens HealthcareSiemens Healthcare•• ChristianneChristianne LeideckerLeidecker, PhD, PhD

�� Philips Healthcare, N.A.Philips Healthcare, N.A.

�� Toshiba America Medical SystemsToshiba America Medical Systems•• Rich Mather, PhDRich Mather, PhD

•• Kirsten L.Kirsten L. BoedekerBoedeker, PhD, PhD


�� Michael A.Michael A. TresslerTressler, MS, DABR, MS, DABR

�� Chad M. Dillon, MSChad M. Dillon, MS

ResourcesResources

�� ACRACR•• 11--800800--227227--54635463

�� Staff available to answer questionsStaff available to answer questions�� Technical questions passed onto Physics subcommitteeTechnical questions passed onto Physics subcommittee

•• www.acr.org/accreditationwww.acr.org/accreditation�� Medical PhysicistMedical Physicist�� VendorVendor

•• Service engineerService engineer•• Applications SupportApplications Support•• Operators ManualOperators Manual•• Tips for AccreditationTips for Accreditation

�� ImPACTImPACT•• ImPACTscan.orgImPACTscan.org

ACRACR

�� Phantom Testing InstructionsPhantom Testing Instructions�� Phantom Testing CriteriaPhantom Testing Criteria

•• Take home test with the answers!Take home test with the answers!

�� Medical Physics 31(9) September 2004Medical Physics 31(9) September 2004•• Practical Tips, Artifact Examples, Pitfalls to AvoidPractical Tips, Artifact Examples, Pitfalls to Avoid

�� FAQFAQ’’ss•• Detector configurations (GE LS example)Detector configurations (GE LS example)•• Helical to axial conversionHelical to axial conversion•• Toshiba DoseToshiba Dose•• Toshiba FOV and CT numbersToshiba FOV and CT numbers

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Resource PersonnelResource Personnel

�� Qualified Medical PhysicistQualified Medical Physicist•• Qualifications submitted to ACR with EntryQualifications submitted to ACR with Entry

ApplicationApplication•• Experience with various scannersExperience with various scanners

�� Service EngineerService Engineer•• Familiar with scanner operations and capabilitiesFamiliar with scanner operations and capabilities•• Should be available to correct deficienciesShould be available to correct deficiencies•• Service Mode accessService Mode access

�� Applications SupportApplications Support•• Familiar with scanner operations and capabilitiesFamiliar with scanner operations and capabilities

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ScannerScanner’’s Operators Manuals Operators Manual

�� ProPro’’ss•• Detector configurationsDetector configurations•• Available slice reconstructionsAvailable slice reconstructions•• Parameters are definedParameters are defined

�� ConCon’’ss•• Not always easily accessibleNot always easily accessible

�� Soft copiesSoft copies

•• May be difficult to find what is neededMay be difficult to find what is needed

�� Tips for AccreditationTips for Accreditation•• Supplied by some vendors upon requestSupplied by some vendors upon request

Common Reasons for FailureCommon Reasons for Failure

�� Failure to follow instructionsFailure to follow instructions�� Phantom AlignmentPhantom Alignment

•• Major FailureMajor Failure�� Improper scanning parameters usedImproper scanning parameters used

•• Table I protocols do not match Protocols usedTable I protocols do not match Protocols used•• Helical to Axial conversionsHelical to Axial conversions•• mAsmAs vsvs ““effectiveeffective mAsmAs””•• Medical PhysicistMedical Physicist vsvs TechnologistTechnologist

�� Low ContrastLow Contrast DetectabilityDetectability•• Cannot visualize at least all four 6 mm rodsCannot visualize at least all four 6 mm rods

�� DoseDose•• Incorrect parameters usedIncorrect parameters used•• Dose Calculator Excel SpreadsheetDose Calculator Excel Spreadsheet mustmust be usedbe used

ACR PhantomACR PhantomGammexGammex 464464

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Phantom AlignmentPhantom AlignmentGOAL

GOAL

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Alignment tip: A/P and LateralAlignment tip: A/P and LateralScoutsScouts

Lateral

A-P

Lateral

A-P

PASS

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PASS

Table I ParametersTable I Parameters

�� kVpkVp•• Must be tested if not disabled. Does notMust be tested if not disabled. Does not

matter if they are used clinically or not.matter if they are used clinically or not.•• For all scanners, aFor all scanners, a kVpkVp may not be availablemay not be available

for a given time andfor a given time and mAmA combination. Keepcombination. KeepmAsmAs the same and increase the rotation timethe same and increase the rotation timeor keepor keep mA/mAsmA/mAs as close as possible toas close as possible toTable I.Table I.

•• Remember availableRemember available kVpkVp’’ss are entered intoare entered intopage 1 of Site Scanning Data Sheet.page 1 of Site Scanning Data Sheet.


�� mAmA•• TypicallyTypically mAsmAs is displayedis displayed

�� mAsmAs/time =/time = mAmA

•• EffectiveEffective mAsmAs�� EffectiveEffective mAsmAs == mAsmAs/Pitch/Pitch

•• mAmA modulation?modulation?�� Determine averageDetermine average mAmA oror mAsmAs

•• Enter average value into Table IEnter average value into Table I

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mAsmAs

�� GEGE•• mAsmAs == mAsmAs

�� PhilipsPhilips•• mAsmAs/slice = effective/slice = effective mAsmAs == mAsmAs/Pitch/Pitch•• mAsmAs = effective= effective mAsmAs * Pitch* Pitch

�� SiemensSiemens•• EffectiveEffective mAsmAs == mAsmAs/Pitch/Pitch•• mAsmAs = effective= effective mAsmAs * Pitch* Pitch

�� ToshibaToshiba•• mAsmAs == mAsmAs•• Toshiba 32 and 64Toshiba 32 and 64

�� EffEff mAsmAs


�� Time perTime per rotation(srotation(s) in sec) in sec•• Partial scansPartial scans

�� <0.4 sec/rotation<0.4 sec/rotation�� 270270oo rotationrotation�� Affects CTDI measurementsAffects CTDI measurements

•• OverscansOverscans�� 420420oo rotationrotation�� Affects CTDI measurementsAffects CTDI measurements

•• Use Time per 360Use Time per 360oo rotation for doserotation for dosemeasurementsmeasurements


�� Scan Field of View (SFOV)Scan Field of View (SFOV)•• in cm or namein cm or name

�� 25 cm, 50 cm, Large, Medium & Small Body, Head25 cm, 50 cm, Large, Medium & Small Body, Head�� Note: Head and Body use different Bowtie filtersNote: Head and Body use different Bowtie filters

�� Siemens 64 has 70 cm SFOV optionSiemens 64 has 70 cm SFOV option�� Toshiba has 18 cm, 24 cm, 32 cm,40 cm & 50 cmToshiba has 18 cm, 24 cm, 32 cm,40 cm & 50 cm

•• Must use appropriate SFOV for phantom, even thoughMust use appropriate SFOV for phantom, even thoughthe protocol may be differentthe protocol may be different


�� Display Field of View (DFOV)Display Field of View (DFOV)•• 5 cm5 cm –– 50 cm (70cm)50 cm (70cm)•• Select appropriate for phantomSelect appropriate for phantom•• ACR recommends closest to, but not <21 cm for ACRACR recommends closest to, but not <21 cm for ACR

phantom (20 cm phantom)phantom (20 cm phantom)�� 24 cm24 cm –– 25 cm DFOV prevents displayed text obstruction25 cm DFOV prevents displayed text obstruction

•• CTDI bodyCTDI body�� 32 cm diameter32 cm diameter

•• 3535 –– 40 cm DFOV40 cm DFOV

•• CTDI headCTDI head�� 16 cm diameter16 cm diameter

•• 20 cm20 cm –– 35 cm DFOV35 cm DFOV

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�� Reconstruction AlgorithmReconstruction Algorithm•• Equipment manufacturer specificEquipment manufacturer specific

•• High Resolution Chest algorithm is usuallyHigh Resolution Chest algorithm is usuallyLung, Detail or Bone (sharp or very sharp)Lung, Detail or Bone (sharp or very sharp)�� Must use for high resolution image at S120Must use for high resolution image at S120

�� Axial (A) or Helical (H)Axial (A) or Helical (H)•• Indicate mode used for clinical protocolIndicate mode used for clinical protocol

Table I ParametersTable I ParametersDetector ConfigurationsDetector Configurations

�� Z axis collimation (in mm)Z axis collimation (in mm)•• Width of theWidth of the tomographictomographic section along the zsection along the z

axis imaged by one data channelaxis imaged by one data channel•• Note: In MDCT, several detector elementsNote: In MDCT, several detector elements

may be grouped together to form one datamay be grouped together to form one datachannelchannel

�� # Data Channels (N) in a single axial scan# Data Channels (N) in a single axial scan�� N x T = detector configuration = totalN x T = detector configuration = total

effective xeffective x--ray beam widthray beam width

Detector ArraysDetector Arrays z = 20 mm, 16z = 20 mm, 16 vsvs 8 detectors8 detectors

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Equal Width ArrayEqual Width Array

16 det x 1.25 mm

Recon 4i x 5.0 mm

4 det x 1.25 mm

Recon 4i x 1.25 mm

Unequal Width ArrayUnequal Width Array

8 detectors

recon 4i x 5.0 mm6 detectors

recon 4i x 2.5 mm

4 detectors recon 4i x 1.0 mm Note: collimate outer 3rd of

outer detectors

2 detectors recon 2i x 0.5 mm Note: collimate outer half of

detectors

Comparison of Early DetectorComparison of Early DetectorDesignsDesigns

4 x 0.54 x 0.5

30 x 1.030 x 1.0UnequalUnequal3434ToshibaToshiba

2 x 1.0, 2 x 1.5,2 x 1.0, 2 x 1.5,

2 x 2.5, 2 x 5.02 x 2.5, 2 x 5.0UnequalUnequal88SiemensSiemens

2 x 1.0, 2 x 1.5,2 x 1.0, 2 x 1.5,

2 x 2.5, 2 x 5.02 x 2.5, 2 x 5.0UnequalUnequal88MarconiMarconi

16 x 1.2516 x 1.25EqualEqual1616GEGE

DetectorDetectorWidthsWidths

Type ofType ofArrayArray

# of# ofDetectorDetectorelementselements

VendorVendor


�� Pitch (IEC)Pitch (IEC)•• P = I / ( N * T)P = I / ( N * T)

•• I = Table Speed in mm/rotationI = Table Speed in mm/rotation

•• N = # data channelsN = # data channels

•• T = detector width in z axisT = detector width in z axis

•• N * T = collimated xN * T = collimated x--ray beam widthray beam width

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�� Example of PitchExample of Pitch•• I = 15 mm / rotationI = 15 mm / rotation

•• N = 4 data channelsN = 4 data channels

•• T = 2.5 mm detector widthT = 2.5 mm detector width

•• P = (15.0 mm/rotation)/(4 x 2.5 mm)P = (15.0 mm/rotation)/(4 x 2.5 mm)

•• P = 15.0/10.0 = 1.5P = 15.0/10.0 = 1.5


�� PitchPitch•• Determines effectiveDetermines effective mAsmAs

�� == mAsmAs/Pitch/Pitch

•• DeterminesDetermines CTDIvolCTDIvol�� == CTDIwCTDIw/Pitch/Pitch�� Used to also derive DLP and effective doseUsed to also derive DLP and effective dose

Table ParametersTable Parameters

�� Reconstruction Scan WidthReconstruction Scan Width•• Image thickness of reconstruction imagesImage thickness of reconstruction images

�� Reconstruction Scan IntervalReconstruction Scan Interval•• Interval between reconstructed imagesInterval between reconstructed images


�� Dose Reduction TechniquesDose Reduction Techniques•• mAmA modulationmodulation

�� AutoAuto mAmA/Smart/Smart mAmA�� CAREDOSECAREDOSE

�� DoserightDoseright�� Real ECReal EC�� SureSureExposure3DExposure3D

•• Clinical use recorded in Table IClinical use recorded in Table I�� Not used to obtain imagesNot used to obtain images

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CTCT DosimetryDosimetry

�� Must measure CTDI in Axial ModeMust measure CTDI in Axial Mode�� Must use Technique in Table I for Adult Head,Must use Technique in Table I for Adult Head,

Adult Abdomen and Pediatric Abdomen (unlessAdult Abdomen and Pediatric Abdomen (unlessattested)attested)•• UseUse mAsmAs vsvs effectiveeffective mAsmAs

�� Adult Head in Head HolderAdult Head in Head Holder�� Adult Abdomen and Pediatric Abdomen onAdult Abdomen and Pediatric Abdomen on

TableTable�� Must fill all Phantom HolesMust fill all Phantom Holes�� Must use Dose Calculator SpreadsheetMust use Dose Calculator Spreadsheet


�� Must use Clinical/Table I TechniquesMust use Clinical/Table I Techniques�� Must use Axial scan to measure CTDIMust use Axial scan to measure CTDI�� When Clinical protocol is HelicalWhen Clinical protocol is Helical

•• Convert to AxialConvert to Axial•• Use Axial scan with effective xUse Axial scan with effective x--ray beam widthray beam width

closest to clinically usedclosest to clinically used•• Enter detector configuration used to obtain doseEnter detector configuration used to obtain dose

measurementmeasurement•• Adjust Table Speed to provide appropriate PitchAdjust Table Speed to provide appropriate Pitch

�� UseUse mAsmAs not effectivenot effective mAsmAs•• EffectiveEffective mAsmAs will yieldwill yield CTDIvolCTDIvol instead ofinstead of CTDIwCTDIw


�� Must meet Dose CriteriaMust meet Dose Criteria•• Pass/FailPass/Fail

�� Adult Head: 80Adult Head: 80 mGymGy�� Pediatric Abdomen: 25Pediatric Abdomen: 25 mGymGy

�� Adult Abdomen: 30Adult Abdomen: 30 mGymGy

•• Reference ValuesReference Values�� Adult Head: 75Adult Head: 75 mGymGy

�� Pediatric Abdomen: 20Pediatric Abdomen: 20 mGymGy�� Adult Abdomen: 25Adult Abdomen: 25 mGymGy


�� CompareCompare CTDIvolCTDIvol with:with:•• DisplayedDisplayed

•• Dose Calculator ProgramsDose Calculator Programs�� ImPACTImPACT

�� Caveat:Caveat:•• PediatricPediatric

�� Dependent on SFOV usedDependent on SFOV used•• 16 cm16 cm vsvs 32 cm CTDI phantoms32 cm CTDI phantoms

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Tips for successTips for success

�� Follow instructionsFollow instructions�� Know your scannerKnow your scanner

•• Enlist technologist assistanceEnlist technologist assistance

�� Verify Scanner is calibrated and allVerify Scanner is calibrated and allpreviously identified deficiencies arepreviously identified deficiencies arecorrectedcorrected

�� Use resourcesUse resources•• Service engineer should be availableService engineer should be available

�� Be your own reviewer!Be your own reviewer!

The Challenges of CTThe Challenges of CTAccreditationAccreditation

GE CT ScannersGE CT Scanners

Thomas G.Thomas G. RuckdeschelRuckdeschel, MS, DABR, MS, DABRDiagnostic Radiological PhysicistDiagnostic Radiological Physicist

Medical Nuclear PhysicistMedical Nuclear PhysicistAlliance Medical Physics LLCAlliance Medical Physics LLC

GEGE LightspeedLightspeed(4 Detectors)(4 Detectors)

ACR FAQACR FAQ

Provided with accreditationProvided with accreditationmaterialmaterial

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GEGE LightspeedLightspeed 1616

�� Detector ConfigurationDetector Configuration•• 16 x 0.625 mm = 10.0 mm16 x 0.625 mm = 10.0 mm•• 8 x 1.25 mm = 10.0 mm8 x 1.25 mm = 10.0 mm•• Total effective length = 20.0 mmTotal effective length = 20.0 mm•• Helical (# simultaneous slices/rotation time)Helical (# simultaneous slices/rotation time)

�� 2, 4, 8 & 162, 4, 8 & 16

�� Simultaneous slices/rotationSimultaneous slices/rotation•• 2 x 0.625 mm, 4 x 3.75 mm, 16 x 0.625 mm2 x 0.625 mm, 4 x 3.75 mm, 16 x 0.625 mm•• 8 x 1.25 mm, 16 x 1.25 mm, 8 x 2.5 mm8 x 1.25 mm, 16 x 1.25 mm, 8 x 2.5 mm

GEGE LightSpeedLightSpeed 16 CT16 CT

GEGE LightspeedLightspeed 3232

�� Detector ConfigurationDetector Configuration•• 32 x 0.625 mm = 20.0 mm32 x 0.625 mm = 20.0 mm

•• 16 x 1.25 mm = 20.0 mm16 x 1.25 mm = 20.0 mm

•• Total effective length = 40.0 mmTotal effective length = 40.0 mm

•• Helical (# simultaneous slices/rotation time)Helical (# simultaneous slices/rotation time)�� 8 & 328 & 32

�� Simultaneous slices/rotationSimultaneous slices/rotation•• 8 x 0.625 mm, 32 x 0.625 mm, 32 x 1.25 mm8 x 0.625 mm, 32 x 0.625 mm, 32 x 1.25 mm

GEGE LightspeedLightspeed 64 (VCT)64 (VCT)

�� LS VCT (64)LS VCT (64)•• 64 x 0.625 mm = 40.0 mm64 x 0.625 mm = 40.0 mm

•• Helical (# simultaneous slices/rotation time)Helical (# simultaneous slices/rotation time)�� 8, 32 & 648, 32 & 64

�� Simultaneous slices/rotationSimultaneous slices/rotation•• 8 x 0.625 mm, 32 x 0.625 mm, 32 x 1.25 mm8 x 0.625 mm, 32 x 0.625 mm, 32 x 1.25 mm

•• 64 X 0.625 mm64 X 0.625 mm

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GE VCT 64 CTGE VCT 64 CT

SMPTE PatternSMPTE Pattern

�� Usually loaded and stored in BrowserUsually loaded and stored in Browser

�� If not, Use Service BrowserIf not, Use Service Browser•• Image QualityImage Quality

•• Install SMPTEInstall SMPTE

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Slice ThicknessSlice Thickness

�� All requested slice thicknessesAll requested slice thicknessesavailableavailable

�� GE VCT (64)GE VCT (64)•• CT #CT # vsvs Slice ThicknessSlice Thickness

�� > 5.0 mm slice thickness unavailable> 5.0 mm slice thickness unavailable

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Low ContrastLow Contrast

�� Verify that low contrast criteriaVerify that low contrast criteriapass with Clinically usedpass with Clinically usedTechniqueTechnique•• Must visualize all four 6.0 mm rodsMust visualize all four 6.0 mm rods

•• If not, optimize technique, consult withIf not, optimize technique, consult withsite and adjust protocolsite and adjust protocol�� Table ITable I


�� Convert Helical Technique to AxialConvert Helical Technique to AxialTechniqueTechnique•• 4 slice4 slice

Helical = 4 x 3.75 mm = 15 mm , I = 10 mm/rotHelical = 4 x 3.75 mm = 15 mm , I = 10 mm/rotPitch = 1.5Pitch = 1.5

Axial = 4 x 3.75 mm = 15 mm, Table Feed = 0 mmAxial = 4 x 3.75 mm = 15 mm, Table Feed = 0 mm•• 64 slice64 slice

Helical = 64 x 0.625 mm = 40 mm, I = 55 mm/rotHelical = 64 x 0.625 mm = 40 mm, I = 55 mm/rotPitch = 1.375Pitch = 1.375

Axial = 64 x 0.625 mm = 40 mm, Table Feed = 0 mmAxial = 64 x 0.625 mm = 40 mm, Table Feed = 0 mm

The Challenges of CTThe Challenges of CTAccreditationAccreditation

Siemens ScannersSiemens Scanners

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Siemens Sensation 10Siemens Sensation 10

�� Detector ElementsDetector Elements•• 16 x 0.75 mm and 8 x 1.5 mm for a total16 x 0.75 mm and 8 x 1.5 mm for a total

"maximum" effective length of 24 mm @"maximum" effective length of 24 mm @isocenterisocenter


�� Nominal slice widths (AxialNominal slice widths (Axial))•• 0.6 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm,0.6 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm,

3.0 mm, 4.5 mm, 5.0 mm, 6.0 mm, 9.0 mm &3.0 mm, 4.5 mm, 5.0 mm, 6.0 mm, 9.0 mm &10.0 mm10.0 mm

�� Nominal slice widths and simultaneousNominal slice widths and simultaneousslices (Axial)slices (Axial)•• 10 x 0.75 mm, 10 x 1.5 m, 2 x 0.6 mm, 2 x 1.010 x 0.75 mm, 10 x 1.5 m, 2 x 0.6 mm, 2 x 1.0

mm, 6 x 3.0 mm and 2 x 12.0 mmmm, 6 x 3.0 mm and 2 x 12.0 mm


�� Important Notes:Important Notes:•• The 0.6 mm detector is available on HeadThe 0.6 mm detector is available on Head

Work & extremitiesWork & extremities•• 0.75 mm and 1.5 mm are available in all0.75 mm and 1.5 mm are available in all

modesmodes•• 1.5 mm Helical can be reconstructed as1.5 mm Helical can be reconstructed as 2.02.0

mm, 3.0 mm, 4.0 mm, 5.0 mm,mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm,6.0 mm, 7.07.0mm,mm, 8.0 mm & 10.0 mm8.0 mm & 10.0 mm


�� Head (Axial):Head (Axial):

• 0.75 mm can be reconstructed as 0.75 mm,1.5 mm, 3.0 mm & 6.0 mm

• 1.5 mm can be reconstructed as 1.5 mm 3.0mm & 6.0 mm

•• 0.6 mm0.6 mm can be reconstructed as 0.6 mm,can be reconstructed as 0.6 mm,0.75, 1.0, 1.50.75, 1.0, 1.5

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�� Head (Helical):Head (Helical):•• 10 x 0.75 mm10 x 0.75 mm can be reconstructed as 0.75can be reconstructed as 0.75

mm,1.5 mm, 2.0 mm, 3.0 mm, 4.5 mm,mm,1.5 mm, 2.0 mm, 3.0 mm, 4.5 mm, 6.06.0mm,mm, 7.0 mm, 8.0 mm & 10.0 mm7.0 mm, 8.0 mm & 10.0 mm

•• 10 x 1.5 mm10 x 1.5 mm can be reconstructed as 1.5can be reconstructed as 1.5mm, 2.0 mm, 3.0 mm, 4.5 mm,mm, 2.0 mm, 3.0 mm, 4.5 mm, 6.0 mm,6.0 mm, 7.07.0mm, 8.0 mm & 10.0 mmmm, 8.0 mm & 10.0 mm


�� Detailed Head WorkDetailed Head Work::•• 0.6 mm0.6 mm 2 x 0.6 mm can be reconstructed2 x 0.6 mm can be reconstructed

asas 0.6 mm0.6 mm

•• 6 x 0.75 mm can be reconstructed as6 x 0.75 mm can be reconstructed as 0.750.75mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 5.0 mm & 6.0 mmmm, 5.0 mm & 6.0 mm

•• 6 x 3.0 mm can be reconstructed as6 x 3.0 mm can be reconstructed as 4.0 mm,4.0 mm,5.0 mm, 6.0 mm,5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm & 10.0 mm7.0 mm, 8.0 mm & 10.0 mm


�� Abdomen (Axial):Abdomen (Axial):•• 8 x 0.75 mm can be reconstructed as 0.758 x 0.75 mm can be reconstructed as 0.75

mm, 1.5 mm, 3.0 mm & 6.0 mmmm, 1.5 mm, 3.0 mm & 6.0 mm

•• 8 x 1.5 mm can be reconstructed as 1.5 mm,8 x 1.5 mm can be reconstructed as 1.5 mm,3.0 mm & 6.0 mm3.0 mm & 6.0 mm

•• 6 x 3.0 cam be reconstructed as 3.0 mm, 6.06 x 3.0 cam be reconstructed as 3.0 mm, 6.0mm & 9.0 mmmm & 9.0 mm

•• 2 x 5.0 mm can be reconstructed as 5.0 mm &2 x 5.0 mm can be reconstructed as 5.0 mm &10.0 mm10.0 mm


�� Abdomen (Helical):Abdomen (Helical):•• 10 x 0.75 mm can be reconstructed as10 x 0.75 mm can be reconstructed as 0.750.75

mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 5.0 mm & 6.0 mmmm, 5.0 mm & 6.0 mm

•• 10 x 1.5 mm can be reconstructed as10 x 1.5 mm can be reconstructed as 0.750.75mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0mm, 5.0 mm & 6.0 mmmm, 5.0 mm & 6.0 mm

•• 6 x 3.0 mm can be reconstructed as6 x 3.0 mm can be reconstructed as 3.0 mm3.0 mm& 6.0 mm& 6.0 mm

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�� Reconstructed slice widths available inReconstructed slice widths available inAxial ModeAxial Mode::•• 0.6 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm,0.6 mm, 0.75 mm, 1.0 mm, 1.5 mm, 2.0 mm,

3.0 mm, 4.5 mm, 5.0 mm, 6.0 mm, 7.03.0 mm, 4.5 mm, 5.0 mm, 6.0 mm, 7.0mm,mm, 8.0 mm, 9.0 mm & 10.0 mm8.0 mm, 9.0 mm & 10.0 mm

Helical to AxialHelical to AxialSlice ThicknessSlice Thickness

�� Sensation 10Sensation 10•• Abdomen Helical:Abdomen Helical:

�� 10 x 1.5 mm10 x 1.5 mm•• 5.0 mm slice recon5.0 mm slice recon

•• Abdomen Axial:Abdomen Axial:�� 8 x 1.5 mm8 x 1.5 mm

•• 3.0 mm or 6.0 mm slice recon3.0 mm or 6.0 mm slice recon

�� 2 x 5.0 mm2 x 5.0 mm•• 5.0 mm5.0 mm


5.0 mm5.0 mm

4.0 mm4.0 mm

4i x 4.5 mm4i x 4.5 mm

3i x 3.0 mm3i x 3.0 mm6i x 3.0 mm; 2i x 9.0 mm6i x 3.0 mm; 2i x 9.0 mm

2i x 0.6 mm; 1i x 1.25 mm2i x 0.6 mm; 1i x 1.25 mm

2i x 5.0 mm2i x 5.0 mm

Reconstructed imageReconstructed imagethicknessthickness

16 x 1.5 mm16 x 1.5 mm

16 x 0.75 mm16 x 0.75 mm1616HelicalHelical

12 x 1.5 mm12 x 1.5 mm

12 x 0.75 mm12 x 0.75 mm6 x 3.0 mm6 x 3.0 mm

2 x 0.6 mm2 x 0.6 mm

2 x 5.0 mm2 x 5.0 mm

1212AxialAxial

Detector ConfigurationsDetector ConfigurationsMaximum #Maximum #Detectors/rotDetectors/rot

ModeMode

Siemens Sensation 64Siemens Sensation 64Detector ConfigurationsDetector Configurations

�� 64 x 0.6 mm, 20 x 0.6mm, 12 x 0.6 mm64 x 0.6 mm, 20 x 0.6mm, 12 x 0.6 mm�� 24 x 1.2 mm, 3 x 1.2 mm24 x 1.2 mm, 3 x 1.2 mm�� 6 x 3.0 mm, 3 x 6.0 mm, 2 x 9.0 mm6 x 3.0 mm, 3 x 6.0 mm, 2 x 9.0 mm�� 12 x 2.4 mm, 6 x 4.8 mm, 4 x 7.2 mm12 x 2.4 mm, 6 x 4.8 mm, 4 x 7.2 mm�� 3 x 9.6, 2 x 14.4 mm3 x 9.6, 2 x 14.4 mm�� 1 x 5.0 mm, 1 x 10.0 mm1 x 5.0 mm, 1 x 10.0 mm�� 6 x 0.6 mm, 3 x 1.2 mm6 x 0.6 mm, 3 x 1.2 mm�� 2 x 1.8 mm, 1 x 3.6 mm2 x 1.8 mm, 1 x 3.6 mm�� Note:Note:

•• effective length of each element @effective length of each element @ isocenterisocenter�� 32 x 0.6 mm = 19.2 mm32 x 0.6 mm = 19.2 mm

•• ““flyingflying”” focal spot doubles # imagesfocal spot doubles # images�� 64 x 0.3 mm = 19.2 mm64 x 0.3 mm = 19.2 mm

�� 8 x 1.2 mm = 9.6 mm8 x 1.2 mm = 9.6 mm�� Total effective length= 28.8 mmTotal effective length= 28.8 mm

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Siemens Sensation 64 CTSiemens Sensation 64 CT

�� Dose MeasurementsDose Measurements•• Technique may use 64 detector elementsTechnique may use 64 detector elements

•• Axial Techniques permit 32 detector elementsAxial Techniques permit 32 detector elementsonlyonly

•• Important Note:Important Note: ““Flying focal spotFlying focal spot”” uses 32uses 32detector elementsdetector elements

Flying Focal SpotFlying Focal Spot

The ACR instructions state that the CTThe ACR instructions state that the CTdosimetrydosimetry spreadsheet should use thespreadsheet should use the

techniques provided in Table I which shouldtechniques provided in Table I which shouldalso be the techniques thatalso be the techniques that are used clinically. Ifare used clinically. Ifthe technique is 120kVp, 276 effectivethe technique is 120kVp, 276 effective mAsmAs, 0.5, 0.5seconds per rotation, N = 64 and T = 0.6 mm,seconds per rotation, N = 64 and T = 0.6 mm,

Pitch = 0.75 then the Table I should bePitch = 0.75 then the Table I should becompleted as follows:completed as follows:


�� kVpkVp: 120: 120�� mAmA: 414: 414

•• If effectiveIf effective mAsmAs = 276= 276 mAsmAs, Pitch = 0.75, and, Pitch = 0.75, andmAsmAs = effective= effective mAsmAs x Pitch then,x Pitch then,mAsmAs = 276 x 0.75 = 207= 276 x 0.75 = 207 mAsmAs

•• IfIf mAsmAs == mAmA x time in sec then,x time in sec then,mAmA == mAsmAs/time/timemAmA = 207= 207 mAsmAs/ 0.5 sec = 414/ 0.5 sec = 414 mAmA

�� Time per rotation: 0.5 secTime per rotation: 0.5 sec

23


�� Scanner TechniqueScanner Technique•• TT = 0.6 mm and N = 64 ??= 0.6 mm and N = 64 ??•• Flying Focal SpotFlying Focal Spot

�� TT = 0.6 mm and N = 32= 0.6 mm and N = 32

�� Pitch: 0.75Pitch: 0.75�� What is the *Table Speed?:What is the *Table Speed?:

•• Pitch = Table Speed/ N x TPitch = Table Speed/ N x T•• Table Speed = Pitch x N x TTable Speed = Pitch x N x T•• Table Speed = 0.75 x 32 x 0.6 = 14.4 mm/rotTable Speed = 0.75 x 32 x 0.6 = 14.4 mm/rot

* The table speed is not displayed but is determined from the IE* The table speed is not displayed but is determined from the IECCdefinition of Pitch; P = Table speed (mm/rot)/ N x Tdefinition of Pitch; P = Table speed (mm/rot)/ N x T

Service EngineerService Engineer

�� Service ModeService Mode•• Permits all technique combinations for allPermits all technique combinations for all

modesmodes

•• (Rotate) Rot Mode(Rotate) Rot Mode�� ImagingImaging

•• (Stationary) Stat Mode(Stationary) Stat Mode�� Generator testsGenerator tests

•• kVpkVp

•• HVLHVL

Service ModeService Mode

�� ProblemsProblems•• Need service engineerNeed service engineer

•• Difficulty filming from service modeDifficulty filming from service mode

�� QC or Physics Mode?QC or Physics Mode?

24

Anticipated Options for ACRAnticipated Options for ACRAccreditationAccreditation

�� Potential Change of phantom alignment criteria fromPotential Change of phantom alignment criteria fromMajor to Minor deficiency?Major to Minor deficiency?

�� Allow Helical scan with appropriate SFOV for CT #Allow Helical scan with appropriate SFOV for CT #accuracyaccuracy•• Acrylic (+110 to +135)Acrylic (+110 to +135)

�� Use Adult Head protocol for CT# water and sliceUse Adult Head protocol for CT# water and slicethicknessthickness

�� When Abdomen ProtocolWhen Abdomen Protocol kVpkVp is 140is 140 kVpkVp, use 120, use 120 kVpkVpfor CT# accuracyfor CT# accuracy

�� Remove conversion of helical protocol to axial except forRemove conversion of helical protocol to axial except forDoseDose

�� Add to instructions method to determineAdd to instructions method to determine mAsmAs forfor mAmAmodulated techniquesmodulated techniques

Anticipated Options for ACRAnticipated Options for ACRAccreditationAccreditation

�� New definitions and calculations to instructions:New definitions and calculations to instructions:•• AddAdd mAsmAs & effective& effective mAsmAs to Table Ito Table I•• Instructions to include N & T on e submissionsInstructions to include N & T on e submissions•• TT == the width of thethe width of the tomographictomographic section along the zsection along the z--axisaxis

imaged by one data channel. In multiimaged by one data channel. In multi--detectordetector--row CT, severalrow CT, severaldetector elements may be grouped together to form one datadetector elements may be grouped together to form one datachannel. In singlechannel. In single--detectordetector--row CT, the value of T is equal to therow CT, the value of T is equal to thenominal scan width.nominal scan width.

NN == the number ofthe number of tomographictomographic sections imaged in asections imaged in asingle axial scan (one rotation of the xsingle axial scan (one rotation of the x--ray source). This is equalray source). This is equalto the number of data channels used in a particular scan. Theto the number of data channels used in a particular scan. Thevalue of N may be less than or equal to the maximum number ofvalue of N may be less than or equal to the maximum number ofdata channels available on the system.data channels available on the system.

Thank you!Thank you!

outline the challenges of ct accreditation: introduction · siemens sensation 10 important notes:...

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