Picture Archiving andPicture Archiving and
Communications Systems (PACS)Communications Systems (PACS)
considerationsconsid...
DIGITAL IMAGING IN RADIOLOGYDIGITAL IMAGING IN RADIOLOGY
•• DigitalDigital imaging is animaging is an essentialessential c...
•• Computed & Direct Radiography (CR / DR)Computed & Direct Radiography (CR / DR)
•• Digital Subtraction Angiography (DSA)...
The “Big” Picture
• “Digital” Radiology
MRIMRI
CTCT Nuclear MedicineNuclear Medicine UltrasoundUltrasound
Interventional A...
Imaging volume
• Projection imaging 70%
• Fluoroscopy 3%
• Computed tomography 8%
• MRI 6%
• Ultrasound 10%
• Nuclear Medi...
Medical Imaging Modalities
• Common thread
– Digital data (and lots of it!!)
• Problems
– Proprietary structures
– Unknown...
•• RIS (HIS)RIS (HIS)
–– Radiology Information SystemRadiology Information System
•• Transcription, Reporting, Ordering, S...
•• RISRIS--PACS IntegrationPACS Integration
–– Data Synchronization, ValidationData Synchronization, Validation
–– Interpr...
•• TCP/IPTCP/IP
–– Standard Communications ProtocolStandard Communications Protocol
–– The InternetThe Internet
•• HL7HL7
...
Infrastructure
• Platforms
– Clients / workstations
– Servers
• Physical Plant
– Power
– HVAC
– Media
• Networking
– Devic...
Infrastructure Challenges
• Business
– Cost vs. quality patient
care
– Regulatory compliance
– Access to data across
appli...
Infrastructure issues
• Foundation of the digital healthcare enterprise
• Highly available (>99.99%); each “9” $$$$
• Docu...
Image management issues
• Very large datasets impact storage &
communications
• Very large annual volumes require data
pro...
A typical imaging solution
PACS Layout at UC DavisPACS Layout at UC Davis
MWLDICOM
iVault
Modalities
Radiology Reading
iSite Radiology
Storage Mirror...
Workstation Hardware
• Off the shelf hardware: 2 to 3 GHz CPU, multi-
core (dual or quad), Windows XP, 4 GB ram,
PC3200 me...
Workstation Hardware
• Two “classes”
– Primary (Radiologist)
– Clinical (Remote and referring physician)
• Typical primary...
Monitor – decision points
• Size and mode (21 inch portrait, monochrome)
– Based on vertical chest radiograph
• Newer choi...
Typical PACS workstation configuration
•1536x2048
•10 bit
•Grayscale
•400 Cd/m2
Navigation
Monitor
1280x1024
color
Basic Workstation Software Reqt’s
• Filters: sort studies by modality, location, time, etc.
• Worklist functionality: auto...
Archive
• Slow, large archives on early generation PACS
• Migration to “all spinning disk” RAID (redundant
array of indepe...
Spinning disk
archive modules
Server
DICOM
Processors &
load balancing
switch
Database
storage
UCDMC PACS
Current storage:...
DICOM: What the Physicist should know
• Where does DICOM come from?
• What does DICOM do?
• What do the terms mean?
• What...
Where does DICOM come from?
• American College of Radiology
• National Electrical Manufacturers Association
(NEMA)
• Estab...
What does DICOM do?
• Addresses 5 areas of functionality
– Transmission and persistence of complete objects
(images, wavef...
DICOM Abbreviations
• AE title: Application Entity title
• DIMSE: DICOM message service element
• E-R: Entity Relationship...
What does DICOM do?
• DICOM storage
– e.g., CT image storage SOP class, CR image storage SOP class
• DICOM print
– Basic g...
What are DICOM objects?
• “Objects”
– Information Object Definitions “IOD”
– Recipes of items to define an “instance” of a...
From DICOM Part 3: Information Object Definitions
Characteristics of module
Group number
Element number
Unique attribute i...
DICOM Attributes
• Attributes also have a defined “value representation”
Tag VR
Value
Length
Value Field
Value Representat...
What DICOM is needed for a modality?
• Store
• Print
• Modality Worklist
• Performed Procedure Step
• Presentation of Grou...
Conformance Statements
Conformance Statements
Don’t assume that desired
functionality is available
Many capabilities are optional
….. $$
Bottom l...
DICOM Metadata……
How does DICOM affect image quality?
• New PACS user: “When making measurements on
DX images, values come out in pixels in...
PACS capabilities
• Hanging protocols
• API – application program interface
• 3rd party add-ons
• Presentation State
• VOI...
Softcopy Grayscale Presentation State
IOD
– Defines an object which can store or
preserve the “state” of a referenced obje...
OriginalOriginal
Radiologist Presentation StateRadiologist Presentation State
PACS remote access
• Security and firewall considerations
• VPN: virtual private network
– Allows “tunneling” into the fir...
IMAGE COMPRESSIONIMAGE COMPRESSION
•• 1 bit = a light switch,1 bit = a light switch, ONON oror OFFOFF, 0, 0 oror 11 (2 Val...
IMAGE COMPRESSIONIMAGE COMPRESSION
•• Average Radiology Exam is ~ 20MBAverage Radiology Exam is ~ 20MB
•• Lossless Compres...
IMAGE COMPRESSIONIMAGE COMPRESSION
OriginalOriginal
500 Kbytes500 Kbytes
12:1 Wavelet12:1 Wavelet
42 Kbytes42 Kbytes
Compr...
IMAGE COMPRESSIONIMAGE COMPRESSION
OriginalOriginal
80008000 KBytesKBytes
35:1 Wavelet35:1 Wavelet
230230 KBytesKBytes
IMAGE COMPRESSION: HOW MUCH?IMAGE COMPRESSION: HOW MUCH?
How much?
Original Wavelet, 10:1 20:1 40:1
~Visually Lossless ~Cl...
Courtesy of Nicholas Hangiandreou, Mayo Clinic, Rochester, MN
IMAGE DISTRIBUTION:
Web and the Internet
IMAGE DISTRIBUTION:
Web and the Internet
Image
Archive
(TB)
Image
Archive
(TB)
Co...
PACS installation planning
• Location of server and major hardware
• PC requirements for workstations,
environment and pow...
Challenges
• Integration of different systems
• IHE: Integrating the Healthcare Enterprise
– Addresses INTEROPERABILITY of...
PACS quality control
• Interfaces
• Redundancy and emergency backup
• Software verification (distance accuracy
measurement...
SUMMARYSUMMARY
Enterprise distribution of images is crucial
for implementation and application of technology
• Telemedicin...
Electronic Image Distribution
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Electronic Image Distribution

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Electronic Image Distribution

  1. 1. Picture Archiving andPicture Archiving and Communications Systems (PACS)Communications Systems (PACS) considerationsconsiderations J. Anthony Seibert, Ph.D.J. Anthony Seibert, Ph.D. Professor of RadiologyProfessor of Radiology University of California Davis Health SystemUniversity of California Davis Health System Sacramento, CaliforniaSacramento, California Digital Imaging Summit and Workshop forDigital Imaging Summit and Workshop for Veterinary RadiologistsVeterinary Radiologists San Luis Obispo, CaliforniaSan Luis Obispo, California May 29May 29--31, 200831, 2008
  2. 2. DIGITAL IMAGING IN RADIOLOGYDIGITAL IMAGING IN RADIOLOGY •• DigitalDigital imaging is animaging is an essentialessential component ofcomponent of Electronic Imaging, Telemedicine andElectronic Imaging, Telemedicine and Remote DiagnosisRemote Diagnosis •• Steps for digital imagingSteps for digital imaging –– AcquisitionAcquisition –– DisplayDisplay –– DiagnosisDiagnosis –– DistributionDistribution –– ArchiveArchive
  3. 3. •• Computed & Direct Radiography (CR / DR)Computed & Direct Radiography (CR / DR) •• Digital Subtraction Angiography (DSA)Digital Subtraction Angiography (DSA) •• Computed Tomography (CT)Computed Tomography (CT) •• Ultrasound (US)Ultrasound (US) •• Magnetic Resonance Imaging (MRI)Magnetic Resonance Imaging (MRI) •• Nuclear Medicine (NM)Nuclear Medicine (NM) •• Mammography & Breast ImagingMammography & Breast Imaging •• Cardiac, DEXA, Dental, OpticalCardiac, DEXA, Dental, Optical……. etc. etc.. etc. etc. DIGITALDIGITAL IMAGING MODALITIES INIMAGING MODALITIES IN RADIOLOGY & MEDICINERADIOLOGY & MEDICINE
  4. 4. The “Big” Picture • “Digital” Radiology MRIMRI CTCT Nuclear MedicineNuclear Medicine UltrasoundUltrasound Interventional AngioInterventional Angio PACSPACS DigitalDigital RadiographyRadiography
  5. 5. Imaging volume • Projection imaging 70% • Fluoroscopy 3% • Computed tomography 8% • MRI 6% • Ultrasound 10% • Nuclear Medicine 3%
  6. 6. Medical Imaging Modalities • Common thread – Digital data (and lots of it!!) • Problems – Proprietary structures – Unknown data format • Solutions – DICOM and PACS – HL-7 and RIS – Networking and Informatics – IHE integration “profiles”
  7. 7. •• RIS (HIS)RIS (HIS) –– Radiology Information SystemRadiology Information System •• Transcription, Reporting, Ordering, Scheduling, BillingTranscription, Reporting, Ordering, Scheduling, Billing •• PACSPACS –– Picture Archiving and Communication SystemPicture Archiving and Communication System •• Acquisition, Interpretation, StorageAcquisition, Interpretation, Storage •• Integrated Medical ImagingIntegrated Medical Imaging –– RIS, PACSRIS, PACS –– Integrating the Healthcare Enterprise (IHE)Integrating the Healthcare Enterprise (IHE) TerminologyTerminology
  8. 8. •• RISRIS--PACS IntegrationPACS Integration –– Data Synchronization, ValidationData Synchronization, Validation –– Interpretation & Results ReportingInterpretation & Results Reporting •• New OpportunitiesNew Opportunities –– Value Added, PatientValue Added, Patient--less Examinationless Examination –– Computer Aided DiagnosisComputer Aided Diagnosis •• Image Distribution (The Internet)Image Distribution (The Internet) –– Clinical Review, OR, Patients, ConferencesClinical Review, OR, Patients, Conferences –– Enterprise IntegrationEnterprise Integration -- EMREMR –– TeleradiologyTeleradiology Integration and DistributionIntegration and Distribution
  9. 9. •• TCP/IPTCP/IP –– Standard Communications ProtocolStandard Communications Protocol –– The InternetThe Internet •• HL7HL7 –– Health Level 7Health Level 7 –– RIS / HISRIS / HIS •• DICOM 3.0DICOM 3.0 –– Digital ImagingDigital Imaging COmmunicationsCOmmunications in Medicine v3.0in Medicine v3.0 –– PACSPACS •• HTTPHTTP –– HyperHyper--Text Transport ProtocolText Transport Protocol –– The World Wide WebThe World Wide Web Communication ProtocolsCommunication Protocols
  10. 10. Infrastructure • Platforms – Clients / workstations – Servers • Physical Plant – Power – HVAC – Media • Networking – Devices – Media – Topologies • Storage – Hardware – software – Media – Topologies
  11. 11. Infrastructure Challenges • Business – Cost vs. quality patient care – Regulatory compliance – Access to data across applications • Clinical – Information when & where needed – Loss or Corruption not tolerated – Impact on patient care • Technical – Lack of qualified technical professionals – Management of increasing amts of data – 100% data integrity & availability – Security for data distribution and storage – Standards vs. proprietary solutions
  12. 12. Infrastructure issues • Foundation of the digital healthcare enterprise • Highly available (>99.99%); each “9” $$$$ • Documented and diagrammed • Made up of media and electronics • Data must be secure in flight & at rest • Proper planning is CRITICAL • Ongoing infrastructure support is CRITICAL
  13. 13. Image management issues • Very large datasets impact storage & communications • Very large annual volumes require data protection • Variable image retention periods (patient age, exam type, etc.) requires lifecycle management • Variable locations could have an impact on communications delays
  14. 14. A typical imaging solution
  15. 15. PACS Layout at UC DavisPACS Layout at UC Davis MWLDICOM iVault Modalities Radiology Reading iSite Radiology Storage Mirror Enterprise Image Distribution iSite Enterprise Internet infrastructure Customer Care RIS Off-Site Backup Real-time Monitoring Emergency Backup Server Exam Orders HL7 100 BaseT to/from modalities 1000 BaseT to database/server/archive
  16. 16. Workstation Hardware • Off the shelf hardware: 2 to 3 GHz CPU, multi- core (dual or quad), Windows XP, 4 GB ram, PC3200 memory • Video card with 512 MB, PCIe bus,10 bit output display, DICOM GSDF compatible • Gigabit NIC • 16x / 40x DVD / CD ROM • 2 HDD, minimum 100 GB SATA, 3 GB/s, RAID • Audio card for voice input • Barcode reader, voice dictation system, etc.
  17. 17. Workstation Hardware • Two “classes” – Primary (Radiologist) – Clinical (Remote and referring physician) • Typical primary class workstation configuration – 2 high resolution / luminance LCD grayscale monitors • >400 Cd/m2 luminance • 1536 x 2048 pixels (3 MP), 21 inch (52 cm) • Portrait mode – 1 COLOR LCD “navigation” panel • 1600 x 1200 typical, 19 inch diagonal (47 cm)
  18. 18. Monitor – decision points • Size and mode (21 inch portrait, monochrome) – Based on vertical chest radiograph • Newer choices – 30 inch 4 MP, 6 MP, color LCD’s • Color (will likely become the standard) – 3D volume visualization – Ultrasound – Nuclear Medicine – Functional MRI, other
  19. 19. Typical PACS workstation configuration •1536x2048 •10 bit •Grayscale •400 Cd/m2 Navigation Monitor 1280x1024 color
  20. 20. Basic Workstation Software Reqt’s • Filters: sort studies by modality, location, time, etc. • Worklist functionality: automate workflow • Hanging protocols: arrange images and display • Retrieving priors: pre-fetch or all spinning disk • Graphic user interface: tool palette parameters • Mechanical interface: keyboard, mouse, other • User preferences: individual preferences for above
  21. 21. Archive • Slow, large archives on early generation PACS • Migration to “all spinning disk” RAID (redundant array of independent disks) NAS (network attached storage) instantaneous access and “disaster recovery” digital tape backup • Hierarchical storage management (HSM) is becoming less important with 3rd generation PACS • “pre-fetching” and “auto-routing” are becoming less important
  22. 22. Spinning disk archive modules Server DICOM Processors & load balancing switch Database storage UCDMC PACS Current storage: 20+ TB of patient data stored and accessible on demand
  23. 23. DICOM: What the Physicist should know • Where does DICOM come from? • What does DICOM do? • What do the terms mean? • What parts of DICOM does a modality need to support or use? • How does DICOM affect image quality?
  24. 24. Where does DICOM come from? • American College of Radiology • National Electrical Manufacturers Association (NEMA) • Established 1983, first published 1985 • Followup standards in 1988 (ACR-NEMA 2.0) • 1993, DICOM 3.0 published and continuously updated
  25. 25. What does DICOM do? • Addresses 5 areas of functionality – Transmission and persistence of complete objects (images, waveforms, documents) – Query & Retrieval of such objects – Performance of specific actions (e.g. film printing) – Workflow management (support of worklists) – Quality and consistency of image appearance (both display and print) • Network configurations – Application Entity (AE) title, IP address, TCP/IP port number
  26. 26. DICOM Abbreviations • AE title: Application Entity title • DIMSE: DICOM message service element • E-R: Entity Relationship • IP address: TCPIP (internet protocol) address • SOP: Service-object pair • UID: Unique Identifier • VR: Value Representation
  27. 27. What does DICOM do? • DICOM storage – e.g., CT image storage SOP class, CR image storage SOP class • DICOM print – Basic grayscale print management SOP class (SCU only) • Query / Retrieve – Poll a DICOM device for a list of studies or patients, then retrieve one or more • Worklist Management – Download a list of “scheduled procedures” to the modality from the RIS through a worklist management provider (PACS Broker) • Modality Performed Procedure Step (MPPS) – Modality tells RIS that the procedure has been performed
  28. 28. What are DICOM objects? • “Objects” – Information Object Definitions “IOD” – Recipes of items to define an “instance” of a • CT/MR/CR/US/Digital X-ray (DX), digital mammo (MG) etc. • Basic film session (DICOM print) • Scheduled procedure for a worklist – Attributes of the object are defined in modules • Patient module: Patient name, Patient ID • Study module: Study UID, Study Date, Accession Number • ……. And more…….
  29. 29. From DICOM Part 3: Information Object Definitions Characteristics of module Group number Element number Unique attribute identification Type 1 = mandatory, non-NULL Type 2 = mandatory, NULL or empty Type 3 = optional Group number even: “standard” odd: “private”
  30. 30. DICOM Attributes • Attributes also have a defined “value representation” Tag VR Value Length Value Field Value Representation (DICOM part 5; explicit VR syntaxes) Person name (PN) Last^First^Middle (Seibert^James^Anthony) Date (DA) yyyymmdd (20060614) Time (TM) hhmmss.frac (091545.87934)
  31. 31. What DICOM is needed for a modality? • Store • Print • Modality Worklist • Performed Procedure Step • Presentation of Grouped Procedures • Archive Commit • Grayscale Standard Display Function (GSDF) • Grayscale Standard Presentation State (GSPS)
  32. 32. Conformance Statements
  33. 33. Conformance Statements Don’t assume that desired functionality is available Many capabilities are optional ….. $$ Bottom line: Negotiate Test and verify Work with modality and PACS vendors to achieve desired functionality C-store C-echo MWL Q/R PPS Print ……… SOP classes Private tags
  34. 34. DICOM Metadata……
  35. 35. How does DICOM affect image quality? • New PACS user: “When making measurements on DX images, values come out in pixels instead of millimeters. Why? ” • DX IOD requires the DX detector module, which calls for “imager pixel spacing” in DICOM tag (0018,0064) • CT IOD uses the image plane module with pixel spacing defined in tag (0028,1130) • PACS workstation/viewer might not be looking for pixel spacing in the correct location • PHYSICIST AS A TROUBLESHOOTER…….
  36. 36. PACS capabilities • Hanging protocols • API – application program interface • 3rd party add-ons • Presentation State • VOI LUT • De-identification / anonymization (HIPAA) • Part 14 DICOM export • ……… and so on…..
  37. 37. Softcopy Grayscale Presentation State IOD – Defines an object which can store or preserve the “state” of a referenced object (e.g., an image) – Stores image orientation, window/level, measurements, annotations, masking shutters – Radiologist making notes, adjusting window/level will produce a “presentation state” upon marking the study complete
  38. 38. OriginalOriginal Radiologist Presentation StateRadiologist Presentation State
  39. 39. PACS remote access • Security and firewall considerations • VPN: virtual private network – Allows “tunneling” into the firewall – Produces a local IP address for a virtual presence • Image compression – DTS….. Dynamic transfer syntax – JPEG2000….. Similar to DTS, adopted by DICOM standard • Access to UCDMC research PACS
  40. 40. IMAGE COMPRESSIONIMAGE COMPRESSION •• 1 bit = a light switch,1 bit = a light switch, ONON oror OFFOFF, 0, 0 oror 11 (2 Values)(2 Values) •• 1 byte = 8 bits1 byte = 8 bits ‘‘00000000’’00000000’’ toto ‘‘11111111’’11111111’’ (256 Values)(256 Values) •• 1 Kilobyte (KB) = 1,000 bytes1 Kilobyte (KB) = 1,000 bytes •• 1 Megabyte (MB) = 1,000 KB1 Megabyte (MB) = 1,000 KB •• 1 Gigabyte (GB) = 1,000 MB1 Gigabyte (GB) = 1,000 MB •• 1 Terabyte (TB) = 1,000 GB1 Terabyte (TB) = 1,000 GB •• 1 Pedibyte (PB) = 1,000 TB1 Pedibyte (PB) = 1,000 TB •• Average Radiology Exam is ~ 20MBAverage Radiology Exam is ~ 20MB •• 280,000 Exams = ~280,000 Exams = ~ 5.6 Terabytes / year5.6 Terabytes / year @ UCDMC Radiology@ UCDMC Radiology
  41. 41. IMAGE COMPRESSIONIMAGE COMPRESSION •• Average Radiology Exam is ~ 20MBAverage Radiology Exam is ~ 20MB •• Lossless CompressionLossless Compression -- JPEGJPEG –– ~ 2:1 > 10MB~ 2:1 > 10MB XferXfer •• Lossy CompressionLossy Compression -- WaveletWavelet –– ~ 20:1 > 1MB~ 20:1 > 1MB XferXfer •• JPEG 2000JPEG 2000 –– Combines Lossless techniques and Lossy WaveletCombines Lossless techniques and Lossy Wavelet –– Finally standards based Wavelet compressionFinally standards based Wavelet compression –– DICOM approval of advanced compression by 2000?DICOM approval of advanced compression by 2000?
  42. 42. IMAGE COMPRESSIONIMAGE COMPRESSION OriginalOriginal 500 Kbytes500 Kbytes 12:1 Wavelet12:1 Wavelet 42 Kbytes42 Kbytes Compression allows more efficient use of limited bandwidth (e.g., telephone modems)
  43. 43. IMAGE COMPRESSIONIMAGE COMPRESSION OriginalOriginal 80008000 KBytesKBytes 35:1 Wavelet35:1 Wavelet 230230 KBytesKBytes
  44. 44. IMAGE COMPRESSION: HOW MUCH?IMAGE COMPRESSION: HOW MUCH? How much? Original Wavelet, 10:1 20:1 40:1 ~Visually Lossless ~Clinically Lossless Visible Blur
  45. 45. Courtesy of Nicholas Hangiandreou, Mayo Clinic, Rochester, MN
  46. 46. IMAGE DISTRIBUTION: Web and the Internet IMAGE DISTRIBUTION: Web and the Internet Image Archive (TB) Image Archive (TB) Control Software Control Software Review Station Review Station Review Station Review Station Web Servers Web Servers Hospital PCs Hospital PCs Radiology Departments USUSCRCR Clinic PCs Clinic PCs Office PCs Office PCs Home PCs Home PCs Radiologists Remote Radiologists Remote Radiologists Imaging Centers Imaging Centers CTCTMRIMRI Courtesy of Dr. Keith Dreyer
  47. 47. PACS installation planning • Location of server and major hardware • PC requirements for workstations, environment and power considerations • “Mini-PACS” for ultrasound, nuclear medicine – Color monitors – Application specific workstation requirements • Reading room – Lighting – Furniture
  48. 48. Challenges • Integration of different systems • IHE: Integrating the Healthcare Enterprise – Addresses INTEROPERABILITY of systems – Provides INTEGRATION PROFILES and a framework for performing needed functionality and workflow – Scheduled Workflow, ….. • http://www.IHE.org
  49. 49. PACS quality control • Interfaces • Redundancy and emergency backup • Software verification (distance accuracy measurements, quantitative measurements) • MONITORS • Verification of correct data • Display and viewing conditions • Image compression & archiving • Disaster Recovery and backup plans
  50. 50. SUMMARYSUMMARY Enterprise distribution of images is crucial for implementation and application of technology • Telemedicine and teleradiology allow the exchange of technological ideas and implementation in a diverse number of associated fields • The Internet solves many problems, as recognized by the proliferation of web-based PACS and unified patient database (instead of Radiology centric orientation) • New opportunities – Image acquisition and image processing tools – Imaging technology innovation for diagnosis and intervention
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