Evaluation Report - ImPACT CT Scanner Evaluation Centre

February 2003Evaluation ReportNUMBERMDA 03023Dual Slice CT Scanner Comparison ReportVersion 8ImPACT reportMDA Evaluation ReportMDA 03023© Crown Copyright£100 (Free to the NHS)

WHAT YOU CAN EXPECT FROM MDA EVALUATION REPORTSThe Device Evaluation Service (DES) aims to provide independent and objectiveevaluations of medical devices available on the UK market. Specialist centres,mainly in NHS Trusts, do the evaluations under long-term contract to, and inaccordance with protocols approved by, the MDA. The evaluations are usually of aunit supplied by the manufacturer. We would expect this unit to be representative ofthe product on the market but cannot guarantee this. Prospective purchasers shouldsatisfy themselves with respect to any modifications that might be made to theproduct type after MDA’s evaluation. The reports are intended to supplement, notreplace, information already available to prospective purchasers.© Crown Copyright 2003Apart from any fair dealing for the purposes of research or privatestudy, or criticism, or review, as permitted under the Copyright,Designs & Patents Act, 1988, this publication may only be reproduced,stored or transmitted in any form or by any means with the priorpermission, in writing, of the Controller of Her Majesty's StationeryOffice (HMSO).Enquiries concerning reproduction outside those terms should be sentto HMSO at the undermentioned address:The Copyright Unit,The Stationery Office,St Clements House,2 - 16 Colegate,NORWICH,NR3 1BQ

ImPACT – Imaging Performance Assessment of CT ScannersDual Slice CT Scanner Comparison ReportVersion 8, February 2003A report comparing the specification and imaging performance of the following CTscanners:ManufacturerGEGEPhilipsSiemensToshibaScanner modelNX/iNX/i ProMx8000DSomatom Emotion DuoAsteion DualCompiled and prepared by members of the ImPACT groupwww.impactscan.org© 2003, Crown Copyright

Table of ContentsTABLE OF CONTENTS ..........................................................................................2INTRODUCTION......................................................................................................3Purpose of this report ......................................................................................................... 3Comparison methods.......................................................................................................... 3Scanner performance ............................................................................................................ 3Specification comparison....................................................................................................... 3Scanners covered in this report......................................................................................... 4SCANNER PERFORMANCE ..................................................................................5Introduction.......................................................................................................................... 5Dose efficiency..................................................................................................................... 6Head scanning....................................................................................................................... 6Body scanning ....................................................................................................................... 6Spatial resolution................................................................................................................. 7Limiting resolution.................................................................................................................. 7Geometric efficiency ........................................................................................................... 8Clinical scan tables ............................................................................................................. 9Standard brain ....................................................................................................................... 9Standard abdomen ................................................................................................................9Helical abdomen .................................................................................................................... 9Inner ear (1mm) ..................................................................................................................... 9High resolution spine ...........................................................................................................10SPECIFICATION COMPARISON..........................................................................11Scanner gantry................................................................................................................... 11Patient couch ..................................................................................................................... 12X-ray generator .................................................................................................................. 13X-ray tube ........................................................................................................................... 13Detection system ............................................................................................................... 14System start-up and calibration....................................................................................... 14Scan parameters................................................................................................................ 15Helical scanning ................................................................................................................16Scan projection radiograph (SPR) ................................................................................... 16Manufacturers’ performance data.................................................................................... 17Factors affecting image quality........................................................................................ 18Operator’s console ............................................................................................................ 19Main computer ...................................................................................................................20Image storage..................................................................................................................... 21Image reconstruction ........................................................................................................ 223D reconstruction .............................................................................................................. 23Optional features ...............................................................................................................24Installation requirements .................................................................................................. 25Independent workstation .................................................................................................. 26Image transfer and connectivity....................................................................................... 27APPENDIX 1: IMAGE QUALITY ASSESSMENT AND Q.....................................28APPENDIX 2: MANUFACTURERS’ COMMENTS................................................29Responses are included from the following manufacturers : ...................................... 29Response from GE Medical Systems .............................................................................. 30Response from Philips Medical Systems........................................................................ 31Response from Siemens Medical Solutions................................................................... 32APPENDIX 3: IMPACT AND THE MDA................................................................33Background........................................................................................................................ 33ImPACT ............................................................................................................................... 33MDA support to purchasers and users ........................................................................... 332 ImPACT Dual Slice CT Scanner Comparison v 8

Introduction• Purpose of this reportIn January 2000, the UK government announced the funding for the replacement, over athree-year period, of all non-helical CT scanners in use in England.ImPACT produced comparison reports for the seven phases of the purchase program. Theprimary aim of these reports was to aid the equipment selection process by providingcomparisons of CT scanners that are currently on the market. The previous set of ‘BlueCover’ comparison reports generally available was from Phase 7 of the governmentpurchase, in August 2002 (report numbers MDA 02058 (single slice), 02060 (dual),02061 (four slice) and 02059 (eight and sixteen slice)).Version 8 of report was produced to reflect changes in scanners since that date, and inanticipation of the availability of further funds for CT scanner purchase within the NHS.The scope of this report is limited to CT scanners that are capable of acquiring two sets ofattenuation data per tube rotation. Separate reports are available for single, four, six to tenand sixteen slice scanners.• Comparison methodsThe data given in this report are representative of the scanners as of February 2003, and areliable to change as the performance of individual scanner models is changed and upgraded.In particular, optional features such as workstations and software packages may be listed asstandard for the scanner replacement programme, but may not be included in other, separatescanner purchases.There are two main areas for comparison of the scanners, performance and specification.Scanner performanceThis section presents the results of ImPACT’s imaging and dose performance assessment ofeach of the scanners. Although manufacturers generally publish image and dosecharacteristics of their scanners, different measurement techniques and phantoms oftenmake it very difficult to compare results from one scanner against another. The ImPACTperformance assessments utilise standard techniques, and allow a fair, like-with-likecomparison.Specification comparisonThe specification comparison is presented as a side-by-side summary comparison of thespecification of each scanner, workstation and related equipment. It is grouped into a seriesof sub-sections relating to different aspects of the scanner, such as gantry, tube anddetectors etc.ImPACT Dual Slice CT Scanner Comparison v 8 3

Introduction• Scanners covered in this reportAt the time of writing, there are five manufacturers of medical CT scanners; (in alphabeticalorder) GE Medical Systems, Philips Medical Systems, Shimadzu, Siemens AG and ToshibaMedical Systems. Of these, GE, Philips, Siemens and Toshiba produce dual slice scanners.The scanner models in this report are listed in the table below.ManufacturerGEGEPhilipsSiemensToshibaScanner modelNX/iNX/i ProMx8000DSomatom Emotion DuoAsteion DualThe GE NX/i and NX/i Pro are very similar, the main difference being the larger tube andgenerator on the NX/i Pro. The specification comparison section lists them in a singlecolumn, with the differences shown where relevant. The performance data comes from anassessment of an NX/i Pro, but the NX/i has identical imaging performance.Philips acquired Marconi Medical in October 2001. The Philips Mx8000D was formerlymarketed as the Marconi Mx8000D.The Philips Mx8000D has not yet been evaluated byImPACT, therefore no imaging performance measurements are available. The limitingresolution data for the Mx8000D came from the assessment of the Marconi Mx8000 (a fourslice scanner), which is also applicable to the Mx8000D.The Toshiba Asteion Dual has recently been assessed by ImPACT, but reviewed data wasnot available in time for inclusion in this report.4 ImPACT Dual Slice CT Scanner Comparison v 8

Scanner performance• IntroductionIn order to compare the performance of CT scanners, the ImPACT evaluation programmehas developed a range of assessment techniques. These were described in detail inMDA/98/25, Type Testing of CT Scanners: Methods and Methodology for AssessingImaging Performance and Dosimetry. The results of this testing are presented in thissection, which consists of data regarding different aspects of scanner performance.The dose efficiency section looks at the overall image quality of the scanner relative to theradiation dose delivered to the patient, for both head and body scanning. This is presentedin terms of the ImPACT Q value.Spatial resolution compares the ability of the scanners to reproduce fine detail within animage, usually referred to as the high contrast spatial resolution. This is presented as theMTF 50 and MTF 10 values (known as MTF 50 and MTF 10 ) for the limiting clinical resolutionof the scanner.Geometric efficiency examines the z-axis dose utilisation of the scanners. This is expressedas the ratio of the imaged slice thickness to the x-ray beam thickness. In general, scannerswith a high geometric efficiency will not produce large patient doses, particularly fornarrow slice thicknesses, where geometric efficiencies are normally lowest.Clinical scan tables lists the measured image quality and dose parameters for the standardImPACT clinical scans.ImPACT Dual Slice CT Scanner Comparison v 8 5

Scanner performance• Dose efficiencyDose efficiency is a term used to describe the quality of a scanner's images relative to theradiation dose to the patient. It can be expressed in a number of ways. ImPACT normallyuse the 'Q-value', which combines measurements of noise, high contrast resolution, slicethickness and dose to produce an imaging figure of merit (see Appendix 2).The Q 2 values presented in this section are for head and body imaging. The imagingparameters used for these scans are chosen to minimise slight variations that occur fordifferent kV, slice thicknesses, scan times and reconstruction algorithm, by using standardvalues where possible:kV: 120 kV or 130 kV when this is the ‘standard’ operating kV for the scannerSlice thickness: 2 x 5 mm for head, 1 x 10 or 2 x 10 mm for body, depending on thecapabilities of the scanner.Scan time: 1.5 or 2 s for head, 1s or faster for body.Reconstruction algorithm: the algorithm chosen for each scanner is the one that mostclosely matches the average ‘standard’ head and body algorithm (MTF 50 of 3.4 c/cm,MTF 10 of 6.0 c/cm).Reconstruction field of view: 250 mm (head) and 380 mm (body).The mAs setting that would result in a CTDI w of 50 mGy for head and 15 mGy for bodyscanning is listed. Z-sensitivity, image noise at 50 or 15 mGy and MTF values are alsoshown.Head scanningScannerRecon mAs for z-sens Noise MTF 50 MTF 10filter 50mGy (mm) (%) (c/cm) (c/cm)Q 2GE NX/i Std+ 337 5.0 0.30 3.3 6.2 7.1Siemens Emotion Duo H40 235 4.6 0.32 3.5 5.7 6.3MEAN 286 4.8 0.31 3.4 6.0 6.7Body scanningScannerRecon mAs for z-sens Noise MTF 50 MTF 10filter 15mGy (mm) (%) (c/cm) (c/cm)Q 2Siemens Emotion Duo B30 151 9.5 1.3 3.6 6.0 2.1GE NX/i Detl 229 9.4 1.3 3.3 6.1 2.1MEAN 190 9.4 1.3 3.4 6.1 2.16 ImPACT Dual Slice CT Scanner Comparison v 8

Scanner performance• Spatial resolutionThe spatial resolution figures given below show the capabilities of the scanners toreproduce fine detail within an image.Limiting resolution looks at the highest spatial resolution that can be achieved with thescanner, using a clinical reconstruction algorithm.Limiting resolutionScannerRecon. MTF 50 MTF 10filter (c/cm) (c/cm)Marconi Mx8000D E 8.9 17.8Siemens Emotion Duo U90 7.6 13.4GE NX/i Edge 10.2 12.1The scan parameters used for limiting resolution table are those that produce the highestspatial resolution i.e. fine focal spot, long (>1 s) scan time, sharpest reconstructionalgorithm, small reconstruction field of view.ImPACT Dual Slice CT Scanner Comparison v 8 7

Scanner performance• Geometric efficiencyGeometric efficiency is a measure of the scanners dose utilisation in the z-axis. This isexpressed as the ratio of the axial imaged slice section thickness relative to the z-axis doseprofile. For optimum imaging, the geometric efficiency should be 1, but it is often less,especially for narrow beam collimations where post-patient collimation may be necessary tobring the imaged slice thickness closer to the nominal value. Geometric efficiency valuesof greater than 1 are due to the accuracy limits of the measurements.The data is presented in the form of a table and a graph. The table gives geometricefficiency values both for the setting closest to 2 x 1 mm slice thickness and also, whereapplicable, for the slice narrower than 1 mm. The graph presents data for all slice widths,showing how geometric efficiency varies with nominal imaged slice width. The total z-sensitivity figure is measured using fused slices.Error bars on the graph reflect the accuracy of measurements of the section thickness (± 0.2mm) and dose profiles (± 0.2 mm).ScannerSliceThickness(mm)Imagedwidth(mm)Total z-sensitivity(mm)Doseprofile(mm)GeometricefficiencyGE NX/i 2 x 1 1.2 2.3 2.2 1.1Siemens Emotion Duo 2 x 1 1.1 2.1 2.1 1.01.21.0Geometric Efficiency0.80.60.40.2GE NX/iSiemens Emotion Duo0.00 2 4 6 8 10Nominal Imaged Slice Width (mm)8 ImPACT Dual Slice CT Scanner Comparison v 8

Scanner performance• Clinical scan tablesThese are a sub-set of the standard ImPACT clinical scan tables for a range of examinationtypes. It should be noted that exposure parameters listed were those suggested by themanufacturer, but in practice they will vary from site to site. In particular, the settings formA and scan time, which define patient dose, may vary widely from one centre to another.Standard brainHead scan reconstructed to show low contrast brain detail. Listed alphabetically.Scanner kVp mAsScan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10time (s) (mm) (mm) Filter (mGy) (mm) (%) (c/cm) (c/cm)GE NX/i 120 240 2.0 2 x 10 250 Std+ 35 9.4 0.26 3.3 6.2Siemens Emotion Duo 130 255 1.5 1 x 10 250 H20 54 9.5 0.18 3.0 5.1MEAN 45 9.4 0.22 3.2 5.7Standard abdomenAxial abdomen scan. Listed alphabetically.Scanner kVp mAsScan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10time (s) (mm) (mm) Filter (mGy) (mm) (%) (c/cm) (c/cm)GE NX/i 120 175 0.7 2 x 10 380 Std+ 11 9.4 1.2 2.7 4.8Siemens Emotion Duo 130 120 0.8 1 x 10 380 B30 12 9.5 1.4 3.6 6.0MEAN 12 9.4 1.3 3.2 5.4Helical abdomenHelical abdomen scan. Listed alphabetically.Scanner kVp mAsScan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10time (s) (mm) (mm) Filter (mGy) (mm) (%) (c/cm) (c/cm)GE NX/i 120 175 0.7 10.00 380 Std+ 8 10.4 1.1 2.5 4.5Siemens Emotion Duo 130 120 0.8 10 380 B30 12 10.1 1.3 3.6 6.0MEAN 10 10.3 1.2 3.0 5.2Inner ear (1mm)High contrast inner ear exam. Listed alphabetically.Scanner kVp mAsScan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10time (s) (mm) (mm) Filter (mGy) (mm) (%) (c/cm) (c/cm)GE NX/i 120 100 1.0 2 x 1 120 Edge 16 1.2 8.4 10.2 12.1Siemens Emotion Duo 130 135 1.5 2 x 1 120 U90 28 1.1 7.6 7.6 13.4MEAN 16 1.2 8.4 10.2 12.1ImPACT Dual Slice CT Scanner Comparison v 8 9

Scanner performanceHigh resolution spineHigh contrast spine examination. Listed alphabetically.Scanner kVp mAsScan Slice FOV Recon CTDI W z-sens. Noise MTF 50 MTF 10time (s) (mm) (mm) Filter (mGy) (mm) (%) (c/cm) (c/cm)GE NX/i 120 170 1.0 2 x 3 120 Bone 12 3.1 14 7.5 10.1Siemens Emotion Duo 130 165 1.5 2 x 1.5 120 U90 17 1.5 23 7.7 11.4MEAN 14 2.3 19 7.6 10.810 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Scanner gantryGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualGeneration 3rd 3rd 3rd 3rdSlipring Low voltage Low voltage Low voltage Low voltageAperture (cm) 70 70 70 72Scan fields of view (cm) 18, 25, 35, 50 25 and 50 50 18, 24, 32, 40, 50Nominal slice widths for axialscans (mm)2 x 1, 2, 3, 4, 5,6, 7, 10, [2 x 0.5]2 x 0.5,1, 2.5,5, 8, 102 x 1, 1.5,2.5, 3, 4, 5.1 x 6, 8 ,102 x 0.5, 1, 2, 3, 4,5, 8, 10Tilt range (degrees) ± 30 ± 30 ± 30 ± 30Type of positioning lights Laser Laser Laser LaserAccuracy of positioning lights(mm)Info. not available± 0.5 mm atgantry centre±2 mm Info. not availableImPACT Dual Slice CT Scanner Comparison v 8 11

Specification comparison• Patient couchCouch topGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualMaterial Carbon fibre Carbon fibre Carbon fibre Carbon fibreLength and width (cm)Horizontal movement224 x 65 (or 42just for cradle)243 x 67.5 222 x 43 200 x 47Horizontal movement range (cm) 162 200 153 182Horizontal movement speeds(mm/sec)Accuracy/reproducibility of tablepositioning (mm)20, 100 0.5 - 100 1 - 100 10, 100± 0.25 ± 0.25 ± 0.5 ± 0.25Scannable horizontal range (cm):(i) without table top extension 162 165 153 144(ii) with table top extension(s) 162 187 153 155Vertical movementVertical movement range out ofgantry (cm)40 - 95 48 - 100.8 45 - 83 30 - 87Vertical movement range ingantry (cm)81 - 95 86 - 100.8 18.6 73 - 87Minimum couch top heightoutside gantry (cm)40 48 45 30Weight bearing propertiesMaximum weight allowed oncouch (kg)Maximum weight on couch whichstill achieves stated performancespecifications (kg)205 200 200 500180 200 200 20512 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• X-ray generatorGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualType High frequency High frequency High frequency High frequencyLocationRotationassemblyRotationassemblyRotationassemblyRotationassemblyPower rating (kW) 42 [53.2] 60 40 36kV settings available 80, 120, 140 90, 120, 140 80, 110, 130 80, 100, 120, 135mA range and step sizeMax. mA allowed for each kV10 - 350 [10 -440] (5mAsteps)80kV:350[400]mA120kV:350 [440]mA140kV:300 [380]mA28 - 500( 5.5 6.4mm (at 80kV) > 1 (inh) + 1.5Anode heat capacity (MHU) 3.5 [6.3] 6.5 3.5 MHUMaximum anode cooling rate(kHU/min)4.0 (nominal)(claimedequivalent to 6.5)820 [840] 735 700 864Method of cooling Oil to air Oil to air Oil to airGuaranteed tube life200,000 rotations160,000rotations130,000 secondsof scanningOil to air withliquid metalbearings200,000 rotationsImPACT Dual Slice CT Scanner Comparison v 8 13

Specification comparison• Detection systemGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualDetector typeSolid state(HiLight / Lumex)Solid state (Highspeed ceramic)Solid state (UltraFast Ceramic)Solid stateNumber of detectors per row789 (plus 23referenceelements)672 (plus 2referenceelements)2 x 672(channels)896 (plus 1 pairref detectors)Number of elements along z-axis 2 2 2 22Effective length of each elementat isocentre (mm)Total effective length of detectorarray at isocentre (mm)Future option for moreslices/rotation2 x 10 2 x 10 2 x 5 4 x 0.5, 18 x 120 20 10 20Yes (4). Aim tolaunch shortlyYes, 4 or 16slices/rotationavailable now.Yes, 6 slicesavailable nowYes (4). (not'forklift', 3 - 4days)• System start-up and calibrationPower-on to warm-up time (mins)Tube warm-up time from 'cold' tooperating temperature (mins)Time to perform detectorcalibrations at warm-up (mins)Recommended frequency for anyadditional calibration by theradiographerTime to perform these additionalcalibrations (mins)GE NX/i[and NX/i Pro]3 from fully off, 1from standbyPhilipsMx8000D6 from fully off,approx. 2 fromstandbySiemensEmotion Duo11 from fully off,5 from standby2 2 - 3 345 secondsinclusive of warmupIncluded in tubewarm up, noadditional cals.are normallyrequired9 & 45 mins butnot normallyrequiredToshibaAsteion Dual2 from fully off,0 from standby2 (0 in anemergency)3 2 11 per weekAdvised 2 hrspost switch on1 per week2 2 Up to 20Total time from fully off toscanning in an emergency (mins)5 8 - 95 (withoutcheck up)214 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Scan parametersReconstruction fields of view(cm)Nominal slice widths (mm) andnumber of simultaneous slices(axial scans)* = OptionalScan times for axial scans (s)* = partial scansGE NX/i[and NX/i Pro]4.8 - 502 x 0.5*, 2 x 1,2 x 2, 2 x 3,2 x 5, 2 x 7,2 x 10, 9 + 10.53*, 0.8, 1,1.5, 2, 3[0.46*, 0,7, 1,1,5, 2, 3]PhilipsMx8000D2.5 - 50 (0.1steps)2 x 0.5, 2 x 1,2 x 2.5, 2 x 5,2 x 8, 2 x 100.3*, 0.5, 0.75, 1,1.5, 2SiemensEmotion DuoToshibaAsteion Dual5 - 50 0 - 502 x 1, 2 x 1.5,2 x 2.5, 2 x 4,2 x 5. 1 x 6,1 x 8, 1 x 100.5*, 0.67*, 0.8,1, 1.52 x 0.5, 2 x 1,2 x 2, 2 x 3,2 x 4, 2 x 5,2 x 8, 2 x 100.5*, 0.75, 1, 1.5,2, 3kV settings available 80, 120, 140 90, 120, 140 80, 110, 130 80, 100, 120, 135mA range and step sizeMax. mA allowed for each kV10 - 350 [10 -440] (5mA steps)80kV:350[400]mA120kV:350 [440]mA140kV:300 [380]mA28 - 500(1mA steps)90 kV: 500 mA120 kV: 500 mA140 kV: 425 mA30 - 240(1 mA steps)80 kV: 228 mA110 kV: 236 mA130 kV: 240 mA10 - 400(10mA steps)80-120 kV:400 mA135 kV: 350 mAImPACT Dual Slice CT Scanner Comparison v 8 15

Specification comparison• Helical scanningRotation times for helicalscanning (s)Number of simultaneous slices ateach rotation timePitches available for routinescanning (range and increment)Recommended pitches foroptimal image qualityHelical interpolation algorithmsavailableMaximum number of rotations inone helical run at standardabdomen parametersMaximum continuous scan time(s)Starting with a cold tube, themaximum helical scan distanceusing a 1 mm imaged slicethickness and a pitch of 1.5Gantry tilt for helical scanning(degrees)GE NX/i[and NX/i Pro]0.8, 1. 1.5[0.7,1,1.5]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion Dual0.5, 0.75, 1, 1.5 0.8, 1, 1.5 0.75, 1, 1.52 2 2 21.5 and 3(0.75 and 1.5)1.5 and 3180º LI, 360° & z-filter interpolation39 (300mA),56 (250 mA),>60 (210mA)[99 (300mA),110 (270 mA),120 (250mA)]All 0.7s scan time0.5 to 4 (0.25 to2) (0.1 steps)1 to 4 (0.5 to 2)(freelyselectable)1.25 to 3 (0.63 to1.5) (0.25 steps)0.5, 0.75, 1, 1.25,1.75, 2.5, 3.5, 4 1 to 4 (full range) 1.25, 1.5, 1.75,2.25, 2.5, 2.75, 3180º, 360º, highorder non linearfilters200SureView(Adaptive axialinterpolator)100 (100mA)100 (150mA)45 (200mA)All 0.8s scan time180º, 360º,Muscot115(190mA, 0.75s)133(160mA, 0.75s)120 100 100 100225 mm[257 mm]300 mm 375 mm Info. not available±30 ±30 ±30 Info. not available• Scan projection radiograph (SPR)GE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualMaximum SPR length (mm) 1000 1024 1024 1390SPR field dimensions(mm x mm)Angular positions of x-ray tubeavailable for SPR (degrees)Real time imageAccuracy of slice prescriptionfrom the scanogram (mm)Accuracy of distancemeasurements from SPR's takenat isocentre (lateral and axialdirections) (mm)500 x 1000Any angle from0 - 355 (5º steps)Yeswidth: 500length: 100 -1024 (1mmsteps)512 x 10240, 90, 180, 270 AP, PA, LATAvailable nextsoftware releaseStandardwidth:240, 400, 500,length:200 - 1,3900, 90, 180, 270(oblique in 5ºsteps)Yes± 0.25 < ± 1 ± 0.5 ± 0.25± 0.25 ± 0.25 ± 0.5 < ± 0.5 mm16 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Manufacturers’ performance dataImage qualityResolution (lp/cm) for sharpestclinical algorithmContrast, smallest rod size (mm)discernable at given parametersin 20 cm CATPHANGE NX/i Plus[and NX/i Pro]15 lp @ 0% MTF13 lp @ 10%MTF 8.5 lp @50% MTFPerformancealgorithm, 0.7sec scan time,small focus5.0mm @ 0.3%PhilipsMx8000D24.0 lp @ cut off,Ultra-high mode,E algorithm, 25cm FOV5 mm @ 0.3%,120 kVp, 250mAs, 2 x 10 mmslice, EB filterCT number accuracy Info. not available ± 4 HUDoseCTDI 100 for axial standard brainscans at given parameters:- centre of CTDI phantom(mGy/100 mAs)- periphery of CTDI phantom(mGy/100 mAs)CTDI 100 for axial standardabdomen scans- centre of CTDI phantom(mGy/100 mAs)- periphery of CTDI phantom(mGy/100 mAs)Dose profile FWHM (mm)Info. not available120 kVp, 2x5mmslice, 1 sec scanSiemensEmotion Duo15.5 lp @ 0%MTF 130 kV,60mA, 0.8sec,1mm, U90S.5 mm 3 HU 15.8mGy at 90 mAs,0.8 sec, 10 mmat 130 kvair:-1000 ± 10 HU,water: 0 ± 4HU110 kV, 8 mmslice thicknessToshibaAsteion Dual18 lp @ cut off,14.5 lp @ 2%MTF,12.5 lp 10% MTF,FC901 sec.Directlycomparable datanot availableInfo. not availableInfo. not available14.7 13.9 14.4 Info. not available14.2 15.4 15.7 Info. not availableInfo. not available120 kVp, 8mmslice, 1 sec scan110 kV 100 mA1 s scan time8 mm slicethicknessInfo. not available4.6 4.3 4.2 Info. not available7.4 8.8 8.4 Info. not available10: 10.3 (l)7: 8.0 (l)5: 6.2 (l)3: 4.7 (l)2: 3.1 (s)1: 1.6 (s)Info. not available10:9.8,8:8.0,5 : 4.94 : 3.92.5: 2.51.5: 1.41: 1.1Info. not availableImPACT Dual Slice CT Scanner Comparison v 8 17

Specification comparison• Factors affecting image qualityDosePost-patient collimation fornarrow slicesAutomatic mA adjustmentaccording to body dimensions ordensity during examinationNoiseAdaptive filtration for noisereductionResolutionGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualNo Yes No NoSmart mA(standard)Advanced noisereductionN/A CARE Dose YesAdaptive imageenhancement orsmoothing for upto three densityrangesYes (automatic)Yes (userprogrammable)Quarter detector shift Yes Yes Yes YesMoving (dynamic/flying) focalspotNumber of imaging detectors perrowSampling frequencyArtefactsArtefact reduction algorithmsNoYesYes, for all scantimes789 672 672 8961388 HzAdvancedartefactreduction,advanced noisereduction,interative boneoption (IBO),motion correction2,320 views (instandard imagingmode of 0.75srotation time)Iterative bonecorrectionNo1000 Hz 1200 HzModified beamhardening(abdomen,pelvis, shoulder),Motion correction(sequentialmodes)Beam hardeningcorrection, rasterartefactsuppressionprotocol (RASP),stack scanning,automatic patientmotion correction18 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Operator’s consoleImage monitorDiagonal dimension of imagescreen (inches)Number of monitors at console(functions of each if > 1)Image displayGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion Dual21 20 21 2112 (patient set upand acquisition/image review,recon andfilming)1 standard ,(acquisition/review andprocessing). 2ndoptional (shareddatabase)Image display matrix dimensions 512, 768, 1024 1024 1024Usual range of CT numberdisplayed (HU)-1024 to +3071 -1000 to +3094-1024 to +3071(-10,240 to30,710 if metalimplants)2 (acquisition/review andprocessing)512, 512 x 1024,1024-1024 to +8191Accuracy of distancemeasurements in x-y plane (mm)± 0.25 mmdepends on pixelsizeDose informationWeighted CTDI (CTDI W ) orCTDI vol displayed on consoleDose Length Product (DLP)displayed on consoleGeometric efficiency displayedon console when 70% for allcollimations)Not applicable(>70% for allcollimations)>70% for allcollimationsControl methods Mouse, keyboard Mouse, keyboard Mouse, keyboardInfo. not availableMouse, cursor,keyboardImPACT Dual Slice CT Scanner Comparison v 8 19

Specification comparison• Main computerGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualMake and modelSilicon GraphicsO 22 x SiliconGraphics O 2Siemens PC witharray processor;IRS - 2 x PentiumIV, ICS - PentiumIV, ( 2nd console'Wizard' is option)2 x SiliconGraphics O 2Operating system IRIX Unix Windows NT IRIXType and speed of CPUAmount of computer RAM(Mbytes):RU5200, 300MHz2 x RISCprocessor300 MHz (one foreach console)(i) supplied as standard 512 2 x 1024(ii) maximum 512 2 x 1024Pentium IV1.7 GHzNavigator: 1024,Optional Wizard:1536Navigator: 1024,optional Wizard:1536R5000 (scanconsole) R12000(display console)300 MHz2 x 10242 x 102420 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Image storageGE NX/iHard disk storage[and NX/i Pro]Total standard hard disk capacity(Gbytes) available for datastorageMaximum hard disk capacity(Gbytes) available for datastorageStandard hard disk capacity forimage storage (Gbytes andnumber of uncompressed512x512 images)Standard hard disk capacity forstorage of raw data files (Gbytesand no. of data files)Archive optionsArchive optionsCapacity of a single archive disk(Gbytes and no. of images)Time to mount an archive disk ortape (s)Archive data transfer rate(images/s)PhilipsMx8000D36 72SiemensEmotion Duo18 GByte systemdisk, 54 GBytedata diskToshibaAsteion Dual36 72 54 9018,20,000 images18,6000 data filesMOD (standard)2.3 (12,000JPEG losslesslycompressed512 x 512 imagesor 600 raw datafiles)5 - 6 inbackgroundoperation1 (read), 0.7(write)72,54,000 images72, approx. 1800data filesMOD (standard),CD-R (standard)4.1 (15,650512 x 512images. Factor 2-3 compression)Immediate (diskcontinuallyaccessible)Less than 1s perimage18,32,000 images36, 6,000 rawdata filesMOD and CD-R(standard)MOD: 4.1Gb(26,000losslesslycompressedimages), CD-R:0.65Gb (4800compressedimages)256 x 256 matrixapprox 30 for fulldisk4516,000 imagesData from 4,000rotationsRewritable MOD(standard)2.6 (9600512 x 512 images- slightlycompressed)20 for full disk2 - 3 Approx. 1ImPACT Dual Slice CT Scanner Comparison v 8 21

Specification comparison• Image reconstructionGE NX/i[and NX/i Pro]Reconstruction matrix 256, 512Minimum reconstruction intervalin helical scanning (mm)Reconstruction timesTime (secs) from the start of dataacquisition to the appearance ofthe 30th image of a series:PhilipsMx8000D340, 512, 768,1024SiemensEmotion DuoToshibaAsteion Dual256, 512 256, 5120.1 0.1 0.1 0.1(i) standard axial brain scan 60 (with IBO) 23 45(ii) axial spine scan 47 23 45(iii) helical abdomen scan 48 23 32Parallel processing detailsSimultaneous scanning andreconstructionAny delay in either scanning orreconstruction when performedconcurrentlySimultaneous scanning androutine analysisSimultaneous scanning andarchiving and/or hard copyingSimultaneous scanning andtransfer to secondconsole/workstation50 prospective,65 retro.45 prospective,60 retro.35 prospective,50 retro.Yes Yes Yes YesNo No No NoYes Yes Yes YesYes Yes Yes YesYes Yes Yes Yes22 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• 3D reconstruction3D Reconstruction on mainconsole (MC) andworkstation (WS)MIPs and MinIPs (maximum andminimum intensity projections)SSD (3D shaded surface display)3D volume rendering software3D virtual endoscopyMPR (multi-planarreconstruction)Planes available in MPRGE NX/i[and NX/i Pro]MC - standard,WS - standard(MIP & MinIP)MC - optional,WS - otandard(3D)MC - N/A,WS - standard(VolumeRendering)MC - optional,WS - standard(Navigator)MC - standard,WS - standard(MPR & MPVR)All planes asdefined byoperator in realtime. MPVR isalso std & realtimePhilipsMx8000DMC - standard,WS - standard(Angio MIP)MC - standard,WS - standard(3D SSD)MC - standard,WS - standard(Vol Rend 4DAngio)MC - option,WS - option(V-endo Voyager)MC - standard,WS - standard(MPR)All planes, anyoblique (identicalon console andworkstations)SiemensEmotion DuoMC - standard,WS - standardMC - standard,WS - standardMC - optional,WS - standardMC - optionalWS - optionalMC - standard,WS - standardAxial, sagittal,coronal, oblique,curvilinearToshibaAsteion DualMC - standard,WS - standardMC - standard,WS - standardMC - standard,WS - standardMC - optional,WS - standardMC - standard,WS - standardAxial, sagittal,coronal, oblique,curved with crosscut through thecurved reformatImPACT Dual Slice CT Scanner Comparison v 8 23

Specification comparison• Optional featuresGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualContrast injector Optional Optional Optional OptionalContrast media bolus trackingCT fluoroscopy software andhardwareStandard(SmartPrep)OptionalStandard(BolusPro Ultra)Optional(Continuous CTImaging)Standard(CARE Bolus)Optional (CAREVision)StandardOptionalHard-copy imaging device Optional Optional Optional OptionalRadiotherapy planningaccessoriesRadiotherapy planning table topOptional (RT flatpad and 'Exact'couch top)Optional (Exacttable top)OptionalOptionalCarbon fibre breast board Optional Optional Optional N/AMeans for attaching patientimmobilisation devices and astereotactic frame to the end ofthe couchSoftware packages on mainconsole (MC) andworkstation (WS)Bone mineral densitometryCT angiographyDentalRadiotherapy CT simulationsoftwareProspective ECG-triggeredcardiac softwareRetrospective ECG-gatedcardiac softwareOptional (Exactcouch E8505M)MC - N/A,WS - optional(PC option)BMDMC - standard,WS - standard(including MIPMinIP Average)MC - optional,WS - optional(Dentascan)MC - N/A,WS - standard forCT Simpurchase,otherwiseoptionalN/AMC - N/A,WS - optionalOptional Optional OptionalMC - optional,WS - optional(Q BMAP II)MC - standard,WS - standard(Angio MIP)MC - optional,WS - optional(DENT -3)MC - optional,WS - optional(AcQsim orSmartSim)MC - optional,WS - N/AMC - optional,WS - N/AMC - optional,(Osteo CT)WS - optionalMC - standard,WS - standardMC - optional,(Dental CT)WS - optionalAvailable from3rd partyMC - optional,WS - N/AN/AMC - optional,WS - N/AMC-standard,WS-standardMC - optional,WS - optionalMC - optional,WS - N/AMC - optional,WS - N/AMC - optional,WS - N/A24 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Installation requirementsEnvironmental requirements(max/min temperature, humidity)in scanner roomEnvironmental requirements(max/min temperature, humidity)in scanner control roomPeak heat output from systemduring scanning (kW)GE NX/i[and NX/i Pro]20 - 28 ºC,30 - 70% noncond. humidity20 - 28 ºC,30 - 70% noncond. humidity3.9 (120kV,300mA, 1s scantime, 280 scansper hour)PhilipsMx8000D15 - 30 °C,relative humidity40 - 60%15 - 30 °C,relative humidity40 - 60%SiemensEmotion Duo18 - 30 ºC,relative humidity15 - 75%,15-28 ºC,relative airhumidity 15-75 %ToshibaAsteion Dual16 - 28 ºC,humidity 40 -80%16 - 28 ºC,humidity 40 -80%13.5 4.7 10.6 maxSystem cooling method Output to air Water/ Air Output to air Output to airAir conditioning requirements forscanner room of minimum floorareaMinimum floor area required forthe system (m 2 )Dimensions of:(i) Gantry (H x W x D (mm)) andweight(ii) Couch (H xW x L (mm)) andweight(iii) Supplementary units(H x W x D (mm)) and weightPower supply requirementsRecommendedNot requiredother than forpatient comfort18 251850 x 1820 x911 1190 kg995 x 650 x 2240295 kgPowerDistribution Unit:820 x 550 x 700,157kg3 phase 380-480V, 100kVA2050 x 2290 x980 2100kg480 x 670 x 2550500kgPower Cabinet:1800 x 900 x 750550kg3 phase 380-480V, 90kVANone18, though 22recommended1780 x 770 x2300 1200kg890 x 680 x 2260400kgNone3 phase 200-480V, 48kVANot necessarybutrecommended201760 x 1970 x870 1300kg390 x 620 x 2390330kgTransformer:980 x 800 x 770,550kg3 phase 380-440V, 75kVAImPACT Dual Slice CT Scanner Comparison v 8 25

Specification comparison• Independent workstationGE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion DualIs a workstation provided?StandardStandard(MX VIEW Exo)Standard(Leonardo)Standard(AlatoView)Computer make and model HP X4000 Dell XeonOperating systemLinux Red Hat7.3Type and speed of CPU 2 x 2.2 GHz 2 GHzSiemens FujitsuPentium 4Silicon GraphicsO 2Windows NT NT UnixPentium (at least1.7 GHz)R12000, 300MHzAmount of computer RAM(Mbytes):(i) supplied as standard 2048 4096 1024 1024(ii) maximum 4096 4096 3072 1024Total hard disk storage capacity(Gbytes):(i) supplied as standard 163 73 36 27(ii) maximum 163 73 36 27Archive optionsCapacity of a single archive disk(Gbytes)Environmental requirements(max/min temperature, humidity)for workstationMOD (standard)4.6 (9400losslesslycompressed512x512 imagesor 700 raw datafiles)10 - 40 ºC,20 - 80 % relativenon-condensinghumidity at 40 ºCMOD (standard)CD-R (optional)9.1 (36,000losslesslycompressed512 x 512images)0 - 40° CCD-R (standard)MOD (optional)MOD: 4.1Gb(26,000losslesslycompressedimages) CD-R:0.65Gb (4800compressedimages)256 x 256 matrix15 - 30 ºC,20 - 85% relativehumidityMOD (optional)2.6 (9600512 x 512 images- slightlycompressed)16 - 28 ºC,humidity 40 -80%26 ImPACT Dual Slice CT Scanner Comparison v 8

Specification comparison• Image transfer and connectivitySpeed of scanner/workstationconnections to local areanetworks (Mbits/s)Remote PC access to images onworkstationDICOM service classes providedby CT console (SCP and SCU)DICOM service classes providedby Independent workstation(SCP and SCU)GE NX/i[and NX/i Pro]PhilipsMx8000DSiemensEmotion DuoToshibaAsteion Dual100 100 100 100OptionalStorage SCU andSCP,query/retrieveStorage SCU andSCP,query/retrieveOptionalEasy-WebStorage SCU andSCP,query/retrieve,printStorage SCU andSCP,query/retrieve,printOptionalStorage SCU andSCP,query/retrieve,print, modalityworklistStorage SCU andSCP,query/retrieve,printOptionalStorage SCU andprint (standard),storage SCP andmodality worklist(optional)Storage SCU andSCP,query/retrieve,printImPACT Dual Slice CT Scanner Comparison v 8 27

Appendix 1: Image quality assessment and QStatistical noise, spatial resolution and slice sensitivity are fundamental parametersdescribing the amount of object information retrievable from an image, or its image quality.X-ray dose can be regarded as a 'cost' of this information. In general, it is meaningless toquote any one of these measurements without reference to the others. The Q-valueincorporates the dose, noise, spatial resolution and slice width into one number. This figureis derived from a relationship between image quality and dose received.A dose efficiency factor has a fundamental meaning, in that a dose efficient scanner willproduce good resolution at minimum dose and noise. However, it can take a number offorms depending on how the various parameters are measured and quoted.The Q-value used in this comparison report, Q 2 , is the same one used in Comparison Report12 (MDA/00/11), which was modified from the previous value used by ImPACT, Q 1 .Q 2 is defined as follows:Q2=fav2σ z CTDI13wwhere:σ = image noise, expressed as a percentage for a 5cm 2 region of interest at the centre of thefield of view in the standard ImPACT water phantoms.f av = spatial resolution, given as (MTF 50 + MTF 10 )/ 2Where MTF 50 and MTF 10 are the spatial frequencies corresponding to the 50% and 10%modulation transfer function values respectively (in line pairs per cm).z 1 = the full width at half maximum (FWHM) of the imaged slice profile (z-sensitivity).This is measured using the inclined plates method for axial imaging, and using a 0.1mmthickness, 6mm diameter tungsten disc for helical scanningCTDI w = weighted CT dose index, as defined in EUR 16262The Q-factor is in part empirical and it should be used with caution. It is not an absolutefigure, as its derivation relies on assumptions of the shape of convolution filter used.Comparisons between scanners will be more reliable when comparing scans reconstructedwith similar convolution filters. It is of most importance when considering the standardscans for head or body. The uncertainty in this value is up to about ±15%, with aconservative estimate of ±10%.28 ImPACT Dual Slice CT Scanner Comparison v 8

Appendix 2: Manufacturers’ comments• Responses are included from the following manufacturers :GE Medical SystemsPhilips Medical SystemsSiemens Medical SolutionsImPACT Dual Slice CT Scanner Comparison v 8 29

Appendix 2: Manufacturers’ comments• Response from GE Medical Systems2nd May 2001ImPACT 2-Slice CT Comparison ReportsDear SueThank you, for the draft version of the report.We were pleased with the results of the comparison, which confirm the high image qualityand low dose nature of these scanners.We are happy that these measurements are representative of the NX/i CT Scanners.Please note that the horizontal movement range is in fact 160cm, and not 162cm as stated.The figure of 162cm has been taken from a service manual, as this range is possible inservice mode onlyKind regardsYours sincerelyPaul MorganCT Clinical Scientist30 ImPACT Dual Slice CT Scanner Comparison v 8

Appendix 2: Manufacturers’ comments• Response from Philips Medical SystemsDear Sue,Thank you and all the ImPACT team for all your work on producing a thorough Blue CoverReport for the CT scanner comparison and assessment.On behalf of Marconi Medical Systems we have no additional comments to make and lookforward to receiving a hardback copy and working with you all in the future.Best RegardsDerek TarrantCT Product ManagerMarconi Medical Systems UK28/05/01ImPACT Dual Slice CT Scanner Comparison v 8 31

Appendix 2: Manufacturers’ comments• Response from Siemens Medical Solutions10/05/01ImPACT Comparison Reports; Manufacturer's ResponseDear Sue,Thank you for your invitation to respond to the ImPACT Comparison report. Firstly, wewould like to acknowledge the work and effort that you and your team have put into thesereports. Tremendous efforts have been made by all involved to deal with this.Of course specifications are changing as each CT system evolves. For example the EmotionCT system is now delivered with a new filter which results in reduced dose. Thus, I realiseit is simply not possible to provide a continuous comprehensive report with the rate ofchange taking place. So I think it is reasonable to recognise the work done and propose notto comment on, for example, specifications that may have changed between original reportand this version of the publication in relation to each individual system.However, whilst you do not wish for a detailed response from us, there is one generalaspect we would wish to highlight in some reasonable detail and I hope that you agree thatthis is appropriate. I am referring to the 'Q' factor, which reduces a complex issue of imagequality to a single number combining spatial resolution, dose and noise level at the centre ofrotation. We note that you do point out the limitations of the 'Q' factor in the appendices,however, it could be possible for some clinical teams to take this factor and regard it as acategorical statement regarding dose efficiency. Perhaps I could focus on the VolumeZoom, though this would affect any system. Since this 'Q' factor places the Volume Zoomin a ranking amongst different manufacturers in a poor position, we believe that theperformance of this system in delivering outstanding clinical images is not properlyreflected in this ranking.We look forward to continuing to work with you in the future.Yours sincerelyDavid ForrestProduct Manager CT32 ImPACT Dual Slice CT Scanner Comparison v 8

Appendix 3: ImPACT and the MDA• BackgroundOne of the roles of the Medical Devices Agency (MDA) is to fund evaluation programmesfor medical devices and equipment. The programme includes evaluation of x-rayComputed Tomography Equipment currently available on the UK market.MDA aims to ensure that evaluation techniques keep abreast of improvements in CTimaging performance and that MDA reports present evaluation information that is timely,useful and readily understood.• ImPACTImPACT (Imaging Performance Assessment of Computed Tomography) is the MDA's CTevaluation facility. It is based at St George's Hospital, London, part of St George'sHealthcare NHS Trust.ImPACT have developed test objects and measurement procedures suitable for intercomparingCT scanner performance. For each CT evaluation hundreds of images areobtained from the system under test and subsequently analysed using custom writtensoftware. Dose measurements are made using ion chambers, and x-ray film is used to obtainadditional x-ray dose information.Members of ImPACT contributing to and writing this report: N. Keat, D. J. Platten,, M. A.Lewis, J. F. Barrett and S. Edyvean (ImPACT Group Leader).• MDA support to purchasers and usersThe ImPACT team is available to answer any queries with regard to the details of thisreport, and also to offer general technical and user advice on CT purchasing, acceptancetesting and quality assurance.ImPACTBence-Jones OfficesSt. George's HospitalLondon SW17 0QTTel: 020 8725 3366Fax: 020 8725 3969email: impact@impactscan.orgweb site: http://www.impactscan.orgMDA contact point for general information on the CT evaluation programme:Arthur GoodmanProgramme ManagerRoom 1207, Hannibal HouseElephant and CastleLondon SE1 6TQTel: 020 7972 8156Fax: 020 7972 8105ImPACT Dual Slice CT Scanner Comparison v 8 33

MEDICAL DEVICES AGENCYMDA Evaluation ReportsMDA evaluation reports are published by the Medical Devices Agency, an Executive Agency of the Department ofHealth. They are available free of charge to the UK National Health Service (NHS), and are for sale to commercialorganisations and other interested parties. A free catalogue of available reports can be obtained from the OrdersDepartment, or downloaded from the MDA web site:http://www.medical-devices.gov.ukOrderingSend your order to the address given below, stating the number, title and quantity of each report required. Yourreports will be despatched by second class post the following working day. If you are not a representative of theNHS, you will be invoiced separately. Non-NHS customers are reminded that it is not possible to offer refunds forreports ordered in error.EnquiriesOrders DepartmentRoom 1207Medical Devices AgencyHannibal HouseElephant and CastleLondonSE1 6TQTel: 020-7972 8181Fax: 020-7972 8105E-mail: dep@medical-devices.gov.ukGeneral publication enquiries should be directed to the Orders Department:Tel: 020-7972 8181Fax: 020-7972 8105E-mail: dep@medical-devices.gov.uk

ISBN 1 84182 705 3Smart number 36 30677 1