basic principles of pacs networking emily seto medical engineering/sims center for global ehealth...
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Basic Principles of Basic Principles of PACS NetworkingPACS Networking
Emily Seto
Medical Engineering/SIMS
Center for Global eHealth Innovation
April 29, 2004
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OverviewOverview
• PACS Introduction
• PACS Network Related Concepts
• Network Lingo and Relevance to PACS
• Example of PACS Network
• Take Home Message
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PACSPACS == PPictureicture Archiving &Archiving & CCommunicationsommunications SSystemystem
System facilitating viewing & storage of digital medical images
What is PACS?What is PACS?
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Medical Digital ImagesMedical Digital Images
CT
MRIUltrasound
CR
Nuclear Med (PET)Light
Fluoroscopy
Mammography
X-RAY BASED
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Acquisition Processing Storage Viewing
HIS RIS
PACS
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PACS Network Related PACS Network Related ConceptsConcepts
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Reliability/SecurityReliability/Security
• Mirrored systems separated by physical distance
• Archived data• Redundant paths (consider direct path from
acquisition device to particular PACS PC)• 24/7 Support (access network remotely)• Secure lines outside of hospital to view
images–eg via Virtual Private Network from
physicians’ homes
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SpeedSpeed
• Online, Near-line & Disaster Recovery Back-ups
• Prefetching & autorouting (pushing images)
• Local copy vs streaming data• Bandwidth (dedicated LAN)
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CompressionCompression
• Lossy vs non-lossy (up to 3:1)
• Acceptable compression different for each type of image
• Different types (eg wavelet, jpeg)
318 kB 10:1 (30 kB) 100:1 (4 kB)
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Network Lingo and Network Lingo and Relevance to PACSRelevance to PACS
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Local Area Network (LAN)Local Area Network (LAN)
• Computer network that spans relatively small area
• Can be desirable to have dedicated PACS LAN for all PACS devices (acquisition devices, display workstations, storage, and servers)
• Advantages:– Helps ensure adequate bandwidth– Can aide in device management
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Redundant Array of Independent (or Redundant Array of Independent (or Inexpensive) Disks (RAID)Inexpensive) Disks (RAID)
• Combination of multiple disks drives to improve: – Performance
• Data striping (spread out blocks of each file across multiple disks)
– Fault tolerance• Disk mirroring• Dedicated disk for error correction
• 50% of hardware device failures are due to disk failures
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Network Attached Storage (NAS)Network Attached Storage (NAS)
• Storage device taken away from server and directly connected to network
• Devices assigned IP addresses and accessed by clients via a server (gateway to data) or accessed directly by clients
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NAS AdvantagesNAS Advantages
• Centralized storage, security, management, and data back-up
• Servers running different operating systems can all access data
• Expandability (add new device without shutting down servers)
• Fault tolerance (server fails can still access data)
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Storage Area Network (SAN)Storage Area Network (SAN)
• High-speed sub-network of shared storage devices
• Access data via server systems connected to both the LAN and SAN
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SAN AdvantagesSAN Advantages
• Centralized storage, modular scalability, high availability, and increased fault tolerance
• Removes bandwidth bottlenecks with LAN based server storage
• Serverless backup (high speed data backup without using LAN bandwidth)
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Example of NAS/SANExample of NAS/SAN
Load-WeightedServers
Tier 1Storage-redundant paths out-connected byfiber optic cables-most recent studies-non-lossy compression
Tier 2Storage-compressed(lossy)-older studies
Image Display
Image Acquisition Devices
Non-compressedDeep Archive
*NB Entire system should be mirrored offsite
4(2 months later)
1
3
2
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Networking BudgetNetworking Budget
• Mirrored servers & storage (several Terabytes)
• Archiving (magneto-optical tapes, DVD-ROMs, CD-ROMs, etc.)– Petabyte (1024 Terabytes)
• Proper facilities to house servers & storage
• Network infrastructure (network drops, cable, etc)
• Support
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Take Home MessageTake Home Message
• Each institution will have their own PACS networking needs depending on size, type and volume of images, existing network, and budget available
• Main concepts to keep in mind:– Reliability/Security– Speed– Compression
