1. Basic Principles of PACS Networking Emily Seto Medical Engineering/SIMS Center for Global eHealth Innovation April 29, 2004

2. Emily Seto 04/04 2 Overview PACS Introduction PACS Network Related Concepts Network Lingo and Relevance to PACS Example of PACS Network Take Home Message

3. Emily Seto 04/04 3 PACS = Picture Archiving & Communications System System facilitating viewing & storage of digital medical images What is PACS?

4. Emily Seto 04/04 4 Medical Digital Images CT MRI Ultrasound CR Nuclear Med (PET) Light Fluoroscopy Mammography X-RAY BASED

5. Emily Seto 04/04 5 AcquisitionProcessingStorageViewing HIS RIS PACS

6. Emily Seto 04/04 6 PACS Network Related Concepts

7. Emily Seto 04/04 7 Reliability/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

8. Emily Seto 04/04 8 Speed Online, Near-line & Disaster Recovery Back-ups Prefetching & autorouting (pushing images) Local copy vs streaming data Bandwidth (dedicated LAN)

9. Emily Seto 04/04 9 Compression Lossy vs non-lossy (up to 3:1) Acceptable compression different for each type of image Different types (eg wavelet, jpeg) 318 kB10:1 (30 kB)100:1 (4 kB)

10. Emily Seto 04/04 10 Network Lingo and Relevance to PACS

11. Emily Seto 04/04 11 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

12. Emily Seto 04/04 12 Redundant Array of Independent (or 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

13. Emily Seto 04/04 13 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

14. Emily Seto 04/04 14 NAS 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)

15. Emily Seto 04/04 15 Storage Area Network (SAN) High-speed sub-network of shared storage devices Access data via server systems connected to both the LAN and SAN

16. Emily Seto 04/04 16 SAN 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)

17. Emily Seto 04/04 17 Example of NAS/SAN Load-Weighted Servers Tier 1 Storage -redundant paths out -connected by fiber optic cables -most recent studies -non-lossy compression Tier 2 Storage -compressed (lossy) -older studies Image Display Image Acquisition Devices Non-compressed Deep Archive *NB Entire system should be mirrored offsite 4 (2 months later) 1 3 2

18. Emily Seto 04/04 18 Networking 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

19. Emily Seto 04/04 19 Take 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

20. Emily Seto 04/04 20 ? Contact Info: Emily Seto emily.seto@uhn.on.ca (416)340-4800 x6409