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1 5. 의료영상 및 PACS 2011. 4. 13 안병익(firstname.lastname@example.org) Mcomputing.tistory.com@LBSAHN
2 Medical Imaging Tech & PACS CTMRIPET/CTPACSDICOM
3 Why use different methods of imaging ? Cost EffectivenessA good guiding principle in many walks of life is … Always pick the simplest solution for your problem.In many cases the cheapest solution is the best. You do not need to give every pregnant mother in the country an MRI scan.The capital cost of installation varies widely:UltrasoundX-ray CTMRIPET£20k - £100k£500k - £1M£2M - £4M>£5M
4 What is the CT? Mathematical transform to the measured data. Reconstruct n dimension function (image) => projection data of n – 1 dimensionRadon Transform (1917) “Two dimension and three dimension object can be reconstructed from the infinite set of projection data”.The First CT: 1973 in the U.S. 4 minutes scan, thickness of 10mm
5 Concept of CT CT Algorithm ・Getting the shape by back projection of the projection data.・For example, outward view is the quadrangle => it is the cylinderCTAlgorithm
13 Magnetic ResonanceUses equipment producing magnetic fields from 0.5 Tesla to 3 TeslaEarths magnetic field is 50 microteslaCost of equipment is approx £700k per Tesla
14 Obtaining the Data All atoms have a magnetic field or orientation When placed in a strong magnetic field the atomic nuclei align with that fieldPulses of Radio Frequency aimed at area of interest in the bodyImparts high energy state to the nuclei of those areasRelaxation of that state produces resonance which can be detectedLocation and intensity will translate into pixel location and intensity
19 Image Manipulation and Enhancement Two time frames T1 and T2 relate to percentages of nuclei which have resumed normal stateT1 improves resolutionT2 improves sensitivityContrast media can be introducedfMR can monitor specific physiology
23 When Do We Use MRI? Excellent for soft tissue imaging Resolution is goodDoes NOT use ionising radiation but does have some safety issues
24 MR Versus CT MR Digital manipulation Non-ionising Non-invasive Good for soft tissueCan image physiologyTechnique can be altered to account for data requiredExpensiveCTDigital manipulationIonising XraysNon-invasiveGood for range of tissue types, soft tissue to a lesser extentCan only image physiology when used with other modalitiesVariation in technique possibleRelatively Cheap
26 PET / CT 란 ?PET / CT란 양전자 방출 촬영기(Positron Emission Tomography)와 컴퓨터 단층촬영기(Computed Tomography)를 하나로 합친 장비이다.PET / CT 장비는 암 진단에 효과적으로 사용되고 특히 종양을 CT, 감마카메라 등에 비해 월등히 앞선 시기에 진단할 수 있게 되어 암의 조기 진단을 가능하게 한다.검사시간을 크게 단축하여 환자의 고통을 덜어주고 환자에 대한 병원의 의료서비스의 질이 한층 높아질 것으로 예상된다.
27 PET / CT 란 ??PET은 양전자 방출하는 방사성의약품을 이용하여 체내의 미세한 변화를 영상화 하는 최첨단 검사이고, 이용하는 약품에 따라 당 대사, 단백질 대사, 핵산대사, 혈류 등의 다양한 체내변화를 영상으로 얻을 수 있으며, 이중 포도당대사를 관찰하는 검사가 가장 흔히 쓰인다.PET/CT는 이러한 PET과 CT를 동시에 시행하는 검사이다.PET만 시행했을 때 생길 수 있는 정상조직에 의한 진단오류를 최소화하고 진단성능을 향상시킬 수 있게 한다.
29 PET / CT 검사원리PET/CT에서는 양전자를 방출하는 포도당 유사체를 이용합니다. 인체 내에 주사 된 포도당 유사체는 암세포에 집적되고 방출된 양전자(+)는 주변의 전자(-)를 만나서 소멸반응을 일으킨 후 서로 반대방향을 가지는 511 KeV 에너지의 두 개의 감마선으로 변환됩니다. 이 감마선들은 PET/CT의 원형동시계측회로에서 검출되어서 컴퓨터에 위치 정보를 전달하게 되고 컴퓨터에서는 인체 내에 어느 곳에 이상이 있는지를 영상으로 표현해 줍니다.
30 PET / CT 장점 암의 조기발견 암의 분포진단 암 치료 계획에 이용 검사시간의 감소 암이 어디까지 퍼져있는지 판단. 암의 재발진단.암 치료 계획에 이용암이 발견될 경우 , 바로 치료방침을 세울 수 있는 정보까지 제공받을 수 있다.검사시간의 감소최대 40% 절약하여 불편한 환자의 불편을 감소시키고 병원의 생산성도 높이고있다.한 번의 촬영으로 전신을 검사할 수 있다.
31 PET / CT 단점 분화도가 좋은 간암이나 조기위암 등의 진단성능은 조금 떨어진다. 신장 , 요관 , 방광 , 전립선 등 비뇨생식기계 암은 소변으로 인해 진단에 주의해야 한다.대사항진이 높지 않은 3~4 mm 이하의 작은 암은 발견되지 않을 수도 있다는 한계점을 고려해야 한다 .
32 PET / CT로 알 수 있는 질환 PET/CT 의 가장 대표적인 적응증은 암 입니다 .
33 PET / CT 검사종류전신 PET / CT뇌신경계 PET / CT심장 PET / CT
34 전신 PET / CT 방사선의약품을 팔에 정맥주사하고 40분 후에 몸 전체를 CT촬영을 하고, 이어서 PET검사를 시행한다. 폐암, 유방암, 대장암, 두경부암, 림프종, 흑색종, 근골격계암, 자궁경부암, 난소암 등의 조기발견 및 전이여부, 양성과 악성 종양의 감별, 암의 병기결정, 재발여부판정, 항암화학요법제와 수술의 치료효과 한정, 환자의 예후 예측등이 가능하다.
35 신세포암으로 수술 후 별 증상 없었으나, PET/CT시행 후 복부에 임파선 재발을 확인할 수 있다.
36 뇌신경계 PET / CT간질환자의 수술전 검사, 파킨슨씨병, 치매(알츠하이머병)의 진단. 뇌종양, 뇌혈관질환의 진단에 사용한다.기억력 감퇴 등 치매가 의심되는 증상이 있어 이를 조기발견해서 질병진행 억제 치료를 한다면 치매를 예방하는데 도움이 됩니다.일부 운동신경계 질환의 감별진단을 원할 때 이용한다.뇌암 진단 받고 방사선치료를 받은 뒤 잔존하는 암이 있는지의 여부를 MRI에서 알기 어려울 때 이용한다.
38 심장 PET / CT 협심증과 심근경색과 같은 관상동맥 질환을 진단한다. 허혈성 심장질환에서 보다 정확한 생존심근부위의 판정을 원할 때 심근 생존능력을 평가하여 치료방법을 결정하는데 시용한다.
39 What is PACS ? P: Picture, Images & Reports A: Archive, Online, Near line, OfflineC: Communication, Networking, Transfer ProtocolsS: System, Components & ArchitecturePACS: for storage and distribution of images and information when necessary
41 Scale of PACS No. of Beds in Hospital/ Exams per year No. of ModalitiesNo. of SwitchesConsiderations:System connectivity, expandability, reliability and cost-effectivenessConnection among various hospital information system, open architecture,Data migration is painful enough if you have money
42 Types of images1D, 2D, 3D, 4DDifferent DICOM Modality type: Cardiac / PET / 4D U/S…..Image size: Resolution and bit depthImage quality: Bit Depth and resolutionColor / MonochromaticExam. Size: image size x no. of imagesStructured ReportsNew DICOM IOD:Endoscopic & Microscopic images / ECGs / Security Profiles…..IOD=information object definition; Mammo CAD use SR output; DICOM waveform IOD; DICOM visible light IOD; Digital Envelop over Digital Signature
48 PACS – Central Architecture DICOMModalityDiagnosticWorkstations (DICOM)ClinicalWorkstations (DICOM)ImageServer(RAID)Gateway orFrame GrabberDiagnosticWorkstationNon-DICOMModalityFilmDigitizerWeb ServerData BaseServerCR/ DR QAWorkstationArchiveComputedRadiographyor DRRIS
49 Central Architecture Image Server and Database Manager is the HEART Any image, any where, any timeUnique central copyEasy update of dataRequires high performance serversPotential single point of failure at serverBandwidth demanding
51 Distributed Architecture Exams are routed from modality to selected workstationsComplex routing algorithms based on department / user preferenceDifficult to support concurrent review of imagesLess destructive for failure at database server
52 Components of PACS HIS/ RIS Broker ePR gateway Database Server Image Server (RAID)Long Term/ Near line ArchiveNetworksDigitizer
59 Role of Acquisition gateway Compression/ decompression and securityCheck the images for integrityConvert to PACS format (header, byte-order, matrix size)Queue for images (priority) to database server (background)Share the workload and no point of failure for multiple Acquisition gateway
60 Database Server and Image Server RAIDDatabaseServerHIS/RISInterface(Broker)DGRISW/SPCsCR QAFilmDigitizerFrameGrabberCTMRR&FNMCRXRAYUS
61 Database Server (PACS controller) The Heart of the systemIntegration cross point between HIS/RIS and PACS (status update)Create and manages patient foldersManage reading worklists and user profilesManage data transfer within the systemSupport data mining and teaching folders
62 Image Server (RAID)Online (rapid access) exam storage and distribution deviceSupport simultaneous exam input and output transfer operationsUp to Three months of storage capacityScalable capacity
63 What is RAID Redundant Array of Independent Disks Bandwidth equal to sum of disk transfer ratesHighest speed disk storage availableHot Swap2 MB/s12345616 MB/s78ImageParityDisk Array
64 RAID 5 configurationIf disk fails, disk can be rebuilt- fault tolerantHigh data transfer rate for read, write slowerMin. 3 disks to startArray capacity is N-1
65 BandwidthBandwidth is a measure of the information (data) carrying capacity of a network10/100/1000 MB/secInformation FlowData Pipe (Network)
66 Network BottleneckThe bandwidth of an information delivery system is limited to the bandwidth of the slowest component in the systemNetwork Bottleneck
67 Data Compression Data compression reduces the information rate a network must supportUncompressed DataCompressed Data
68 Lossless Image Compression I - D = 0IDDecompressed image is identical to original imageJPEG lossless compressionAverage compression of 2:1 for x-ray images
69 JPEG 2000 CompressionSelected parts of the image can be defined as Regions of Interest, they can then be delivered before other parts of the image, or losslessly, whilst other parts of the image that are less critical use normal lossy compressionJPEG 2000 codestream can be ordered to deliver images of lower resolution before the full image can be transmittedMotion JPEG 2000 does not have any form of extrapolation (and hence potential distortion) in the time domain. Each frame is a separate JPEG 2000 coded image
72 Types of storage media Media DVD MOD DLT 9840 AIT2 GB Cost WORMDLT9840AIT2GB3.85.2352050CostLess Expen.Expen.CheapMost Expen.Load + AssessVery fast113 sec15 sec45 secMax. T rate MB/s55.1106
73 Long Term ArchiveUsed to store digital data for longer periods of timeStorage ranges from 100 MB to 10 TBOptical disk most common media- 5 1/4” MOD- 2.6 GB and 5.2 GB CapacityDLT used for longer term storage and redundancyISP module
75 Storage Area NetworkSAN is a high-speed sub-network of shared storage devicesContains storage device (disk) for storing dataSAN's architecture works in a way that makes all storage devices available to all serversUse of Fiber ChannelHigh scalability for additional storage and redundant networksPCsStorage devices
76 Network Area StorageNAS is a class of dedicated hard disk-based storage devices which provide LAN users with additional disk storage through a standard network connectionIn most cases, a NAS device (or NAS server) receives an IP address, connects to the LAN through an Ethernet cable, and resides on the LAN as an independent network deviceUsers are not demanding the server's processing time for mundane storage tasks -- often improving the performance of local application serversNAS systems also include some onboard memory (RAM) to cache network data to or from the disks
77 SAN Vs NAS Difference between NAS and SAN is subtle NAS devices are big, single purpose storage appliances that you plug into networkNAS sits between your application server and your file systemAs perform only 1 task, can serve files very fastNAS is network-centricSAN is a defined architecture that sits between your file system and your underlying physical storageSAN is data-centric
79 Workstations Four Primary Categories - Advanced Analysis: Used by specialists for advanced diagnosis - 3D, volume renderingDiagnostic: For primary diagnosis; located in reading rooms; high-end 2K monitorsClinical: Used by clinicians and staff to consult; ICU / ER applications; less costly than diagnostic; 1K monitorsAt Home Review: low-end; PC based; cost-effective; review application; lossy compressed for faster transmit
80 Standalone Vs direct PACS w/s Standalone WorkstationDirect PACS Client WorkstationHard Disk StorageYes, variesMinimalQuery PACS numberAll PACS system (CT, ACC, Angio.)Single PACS system (ACC PACS)Retrieval mechanismDICOM Q/R and association made with different vendorsDirect attached, same vendorRetrieval timeSlowerFasterDiagnostic valueDepends on Monitor Grade and Modules like MPR, 3D etcSuggested usagefor meeting/museum purposefor single modality image reviewing and reporting like Radworks in U/S RmDirect PACS workstation for reporting
81 Web distribution High availability, low cost Reports / select images to referring physician desktopPoint of integration with electronic patient recordLossy compression for performancePotential for TeleRadiologySecurity issues to be resolved
83 Broker HIS/RIS and PACS interface DGRISW/SPCsCR QAFilmDigitizerFrameGrabberCTMRR&FNMCRXRAYUS
84 Hospital Information System Support clinical and medical patient care activities in the hospitalAdminister the hospital’s daily business transactions like finance, payroll etcEvaluate hospital performances and costs and make long-term forecast
85 Clinical System in HA, HK Patient AdministrationIn-Patient and Out-Patient Administration SystemAccident & Emergency Information SystemMedical Record Abstract SystemMedical Record Tracking SystemClinical SupportLaboratory Information SystemRadiology Information SystemPharmacy Management SystemDietetics Catering Management SystemClinical ManagementClinical Management System (In-Patient) Discharge SummaryClinical Management System (Out-Patient)Electronic Patient RecordsClinical Data Analysis and Reporting System
86 Non-Clinical System in HA Human Resources and Payroll SystemsHospital Based Financial SystemMaterials Management SystemPatient Billing and Revenue Collection SystemExecutive Information SystemCode 9 and view codes
87 Radiology Information Systems Similar to HIS but of smaller scaleInterfaces to PACS based on HL7Department administrative management- Scheduling and Film tracking- Resource management and reporting- Monitor patient statusLink to Hospital Information System (HIS)- Billing and Master RecordLink to Clinical Management System (CMS)- Prefetch for Clinical visit- ePR integration
88 RIS workflow Exam Order Exam Scheduled Web distribution to referring physiciansRISModality WorklistDemographicsDownloadedPatient ExamIs PerformedImagescopied onweb-serverOrderEventImagestransferredin STSDatabaseserver/ArchivePrefetch ExamsFrom StoragePACS WorklistUpdatedImages /Prior ReportsExamReadDictatedstatusImage migration STS to LTAFinal reportavailableReportVerifiedPreliminary statusExamTranscribed
89 Broker service Database server DR HA HIS CR HA RIS HA CMS US DF Mitra ADTCRMitraPACSBrokerinterfaceHARISAppt.,X-ray requestHA CMSClinical visitUSDFDatabase serverModalities: Get WORKLISTGet REPORT, Get INFO
90 Broker serviceA restricted access account will be created at Sybase that gives limited authority for the DICOM Broker solely for the purpose of the interfacesIn general, for data flow from RIS to the Broker, the RIS write the supported events to the table, and the Broker polls against the events table and calls the associated stored procedures for the conversion to DICOM messages
91 Broker service Broker main function: - Worklist generation - Reports storageRegistration + Post exam data capture (RIS)Acc # generation + call broker for updateNeed SOME time!!Modalities query Broker for worklist updateBroker poll RIS event table and convert to DICOM info
92 ePR ArchitectureSelected images from individual hospital’s PACS are sentmake use of the ePR record indexing and browsing capabilities to read the radiology images through CMS workstations
93 Data Flow Diagram RIS ePR HA system Appointment Attendance Exam recordsReports (15mins)CMSRIS operational dataePRWeb ServerPACSAttendanceExam & workload units (daily)RIS statistical dataData warehouseNon clinical system
94 Characteristics of ePR Near instant image reviewWeb distribution can be within hospital, to other hospitals or even private clinicsTeleRadiography possibleUpdate of patient informationLossy Vs losslessBroken pathway15 minutes time lag
95 Guidelines for HIS, RIS, PACS interface Each system remain unchanged in its configuration and function, only data are sharedIdentify the subset data to be shared and set up access rights/ authorizationConvert the subset data to HL7 standardDefine transfer protocol (TCP/IP or DICOM)
96 Typical patient and data flow Admission: Patient registration, notify HIS (HL7)Order entry/Arrival: Schedule exam and notify RISBroker notified and PACS database server updated (prefetch)DICOM worklist to modalityExam completed: data to DICOM gateway (MPPS)Information/images to database/image server through gateway (DICOM store)Images stored in PACS archiveImages to workstations from PACS archiveDictation, transcription etc: workstation to RIS/PACSRIS reporting and PACS updated for reportsTransfer: HIS/RIS to PACS, images to other PACSDischarge: HIS/RIS to PACS, images rub out
98 What is DICOM?The standard for Digital Imaging and Communications in Medicine.Developed by the National Electrical Manufacturers Association (NEMA) in conjunction with the American College of Radiology (ACR).Covers most image formats for all of medicine.Specification for messaging and communication between imaging machines.
99 A little history The first version was ACR-NEMA, released in 1985. Its goal in developing a standard wasTo enable users to retrieve images and associated information from digital imaging equipment in a standard format using point-to-point connection.To hide differences same across multiple image equipment manufacturers.To handle developing network and image standarts, a new standard, DICOM, was proposed in 1981.
101 Summary of DICOM Features NETWORK PROTOCOLDICOM incorporates negotiation to permit peers to agree on the functions to be performedMESSAGE ENCODINGDICOM defines 24 data types (V2.0 had 4)DICOM message encoding includes JPEG compression (17 varients)DICOM supports multiple character repertoires
102 Summary of DICOM Features OBJECT DATA MODELDICOM is based on a completely specified data modelDICOM includes a robust UID mechanismDATA DICTIONARYDICOM includes a large number of new data elementsSERVICE CLASSESDICOM defines classes of service for specific applications (e.g. image management, printing) and conformance levels
103 DICOM ObjectsThings such as images, reports, and patients are all objects and are called information objects.Two kinds of objects in DICOM:Composite objects (Old objects inherited from NEMA).Normalized objects (New objects defined in DICOM).All objects and their format constitutes Data Dictionary.DICOM uses UIDs to identify information objects, such as the images, reports, or transfer syntaxes.The form of the UID conforms to an international standard.is the root and the same for every DICOM UID.Example: UID for the DICOM explicit VR little endian transfer syntax is
104 DICOM Service Classes Composite Verification Storage Query/Retrieve Study Content NotificationNormalizedPatient ManagementStudy ManagementResults ManagementBasic Print Management
105 Hardcopy Image Reading + Dictation/Transcription (Use Case 1) Hardcopy ReadingHardcopy DICOM Print as Seen at ModalityReporting:RIS-Based Transcription / Validation of Narrative ReportRIS-Based Report Storage and ManagementSend ReportsQuery Prior Reports
107 Hardcopy and Softcopy Image Reading + Dictation/Transcription (Use Case 2) Hardcopy ReadingHardcopy DICOM Print as Seen at ModalitySoftcopy ReadingHardcopy DICOM Print as Seen During Softcopy ReadingReporting:RIS-Based Transcription / Validation of Narrative ReportRIS-Based Report Storage and ManagementSend ReportsQuery Prior Reports
108 Hardcopy and Softcopy Image Reading + Dictation/Transcription (Use Case 2) storeSelectedImagesSoftcopyInterpretation& DictationReport Storage / Mgmt.ReportRepositoryRISElectronic ReportPaper print/Mail/Fax/sendElectronic ReportNarrative Info OnlyqueryAcquisitionTranscription& CorrectionprintValidationFilmingFilm ArchiveHardcopyInterpretation& DictationmanualnetworkDICOMHL7/otheroptional
109 Acquisition Workflow Support + Burn CD/DVD (Use Case 3) Image Acquisition:RIS-based Acquisition Workflow Support (Modality Worklist)Image Reading:Hardcopy ReadingHardcopy DICOM Print as Seen at ModalitySoftcopy ReadingHardcopy DICOM Print as Seen During Softcopy ReadingDICOM Store Images -> Burn CD/DVDReporting:RIS-Based Transcription / Validation of Narrative ReportRIS-Based Report Storage and ManagementSend ReportsQuery Prior ReportsOptional DICOM Store Reports -> Burn CD/DVD
110 Hardcopy and Softcopy Image Reading + Dictation/Transcription (Use Case 3) Modality WorkliststoreSelectedImagesSoftcopyInterpretation& DictationReport Storage / Mgmt.Electronic ReportReportRepositoryRISPaper print/Mail/Fax/sendElectronic ReportNarrative Info OnlyqueryAcquisitionTranscription& CorrectionprintBurn CD/DVDOff-Line ArchiveValidationstoreFilmingFilm ArchivemanualnetworkDICOMHL7/otheroptionalHardcopyInterpretation& Dictation
111 PACS for Management of DICOM Persistent Objects (Use Case 4) Image Acquisition:RIS-based Acquisition Workflow Support (Modality Worklist)Image Reading:Hardcopy ReadingHardcopy DICOM Print as Seen at ModalitySoftcopy ReadingHardcopy DICOM Print as Seen During Softcopy ReadingDICOM Store Images for Burning CD/DVDPACS-based Storage and Management of DICOM Persistent ObjectsArchive Imaging StudiesQuery Prior Imaging StudiesReporting:RIS-Based Transcription / Validation of Narrative ReportRIS-Based Report Storage and ManagementSend ReportsQuery Prior ReportsOptional DICOM Store Reports for Burning CD/DVD
112 PACS for Management of DICOM Persistent Objects (Use Case 4) Modality WorkliststoreObject Storage / Mgmt.Electronic ReportElectronicReportSelectedImagesReportRepositoryRISPaper print/Mail/Fax/sendSoftcopyInterpretation& DictationqueryNarrative Info OnlyTranscription& CorrectionImageRepositoryPACSAcquisitionstoreValidationprintstoreq/rstoreOff-Line ArchiveFilmingBurn CD/DVDFilm ArchiveHardcopyInterpretation& DictationmanualnetworkDICOMHL7/otheroptional