High Availability Technologies for PACS

High Availability Technologies for PACS

Carrison K.S. Tong (Pamela Youde Nethersole Eastern Hospital, HK) and Eric T.T. Wong (Hong Kong Polytechnic Institute, Hong Kong)
DOI: 10.4018/978-1-59904-672-3.ch003
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Abstract

PACS disasters can, and do, appear in a variety of forms including storage hard disk failure, file corruption, network breakdown, and server malfunction. The PACS disasters are commonly classified into hardware, environmental and physical, network, database system, and server failures. A single point of hardware failure in PACS is at the PACS controller, or the main archive server. When it occurs, it renders the entire PACS inoperable and crippled, until the problem is diagnosed and resolved. Recently, various techniques were developed for the prevention of PACS disasters caused by the actual loss and inaccessibility of data. All those techniques are commonly called “High Availability (HA) Technologies” (Marcus, Stern, 2003). The objective of this chapter is to discuss various HA technologies for the prevention of PACS disasters.
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High Available Technologies

Network

Nevertheless, all of the PACS devices still need to be connected to the network (Marcus, Stern, 2003). In order to maximize system reliability, a PACS network should be built with redundancy. To build a redundant network, two parallel gigabit optical fibres are connected between the PACS and the hospital networks forming two network segments using four Ethernet switches. The Ethernet switches are configured in such a way that one of the network segments is in active mode while the other is in standby mode. If the active network segment fails, the standby network segment will become active within less than 300 ms to allow the system to keep running continuously.

Server Clustering

The advantage of clustering computers (Marcus, Stern, 2003) (Huang, 2004) for high availability is seen if one of the computers fails; another computer in the cluster can then assume the workload of the failed computer (Thomas, 2007) at a pre-specified time interval. Users of the system see no interruption of access. The advantages of clustering DICOM Web servers for scalability include increased application performance and the support of a greater number of users for image distribution.

Clustering (Nesbitt, Schultz, and Dasilva, 2005) can be implemented at different levels of the system, including hardware, operating systems, middleware, systems management and applications. The more layers that incorporate clustering technology, the more complex the whole system is to manage. To implement a successful clustering solution, specialists in all the technologies (i.e. hardware, networking, and software) are required. For clustering the Web servers, we can connect all Web servers using a load balancing switch. This method has the advantages of low server overhead and requiring no computer processor power.

Database Cluster

Since the hearts of many medical information systems (Lou, 1997) such as PACS, HIS, and RIS (Smith, 2005) (Huang, 2004) are their databases, protection of the databases is an essential task during the design of a filmless hospital project. Database clustering is one of the most efficient for protection and load balancing of database service. It is a technique to connect several computer servers to provide a high available database service. The advantages of database cluster include:

  • High availability: Able to deliver 99.99% availability using parallel server architecture with no single point of failure.

  • Dynamic scalability: Incrementally scale-out the applications as hospital needs grow.

  • High-Performance: Deliver the performance and throughput required to meet the most demanding hospital applications.

  • No data synchronization: A single database is used without any data synchronization.

Complete Chapter List

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Table of Contents
Chapter 1
Introduction  (pages 1-27)
Carrison K.S. Tong, Eric T.T. Wong
Picture archiving and communications system (PACS) is a filmless and computerized method of communicating and storing medical image data such as... Sample PDF
Introduction
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Chapter 2
Carrison K.S. Tong, Eric T.T. Wong
The protection of information for a healthcare organization, in any form, while in storage, processing, or transport, from being available to any... Sample PDF
ISO 27000 Information Security Management System
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Chapter 3
Carrison K.S. Tong, Eric T.T. Wong
PACS disasters can, and do, appear in a variety of forms including storage hard disk failure, file corruption, network breakdown, and server... Sample PDF
High Availability Technologies for PACS
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Chapter 4
Carrison K.S. Tong, Eric T.T. Wong
Fundamental to ISO 27000 (ISO/IEC 27001:2005, 2005) is the concept of an information security management system (ISMS). The information security... Sample PDF
Implementation of Information Security Management System (ISMS)
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Chapter 5
Carrison K.S. Tong, Eric T.T. Wong
Filmless hospital is transforming at an unprecedented rate. Physicians, nurses, clinicians, pharmacists, radiologists, emergency departments, local... Sample PDF
Planning for a Filmless Hospital
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Chapter 6
Carrison K.S. Tong, Eric T.T. Wong
More rapidly than any technological advance in medical history, filmless hospital is changing the clinical and business aspects of radiology... Sample PDF
Design of a Filmless Hospital
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Chapter 7
Carrison K.S. Tong, Eric T.T. Wong
A PACS has tremendous benefits (Bryan, Weatherburn, Watkins, Buxton, 1999) and values outside of radiology as well as internally. The biggest... Sample PDF
Implementation of Filmless Hospital
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Chapter 8
Carrison K.S. Tong, Eric T.T. Wong
As PACS gains widespread use, the importance of Quality Control (QC), Quality Assurance (QA), and Business Continuity Plan (BCP) in PACS is rising.... Sample PDF
Quality Control, Quality Assurance, and Business Continuity Plan in PACS
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Chapter 9
PACS Quality Dimensions  (pages 140-153)
Carrison K.S. Tong, Eric T.T. Wong
A large number of studies have attempted to identify the factors that contribute to good PACS quality, such as that shown by Reiner et al (2003).... Sample PDF
PACS Quality Dimensions
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Chapter 10
Customer Oriented PACS  (pages 154-169)
Carrison K.S. Tong, Eric T.T. Wong
During the early development phase of PACS, its implementation was mainly a matter of the radiology department. This is changing rapidly, and PACS... Sample PDF
Customer Oriented PACS
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Chapter 11
Carrison K.S. Tong, Eric T.T. Wong
Nowadays it is hard to think of any applications in modern society in which electronic systems do not play a significant role. In aerospace and... Sample PDF
Design for PACS Reliability
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Chapter 12
Carrison K.S. Tong, Eric T.T. Wong
There are some medical errors for which preventability is rarely questioned. These include medical errors such as wrong site surgery, wrong... Sample PDF
PACS Failure Mode and Effects
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Chapter 13
Carrison K.S. Tong, Eric T.T. Wong
Economically speaking, it is interesting to see that over the years, the question as to whether PACS is cost-justifiable has not been easier to... Sample PDF
PACS Network Traffic Control
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Chapter 14
Human Factors and Culture  (pages 225-243)
Carrison K.S. Tong, Eric T.T. Wong
Human factors engineering (HFE) is the science of designing systems to fit human capabilities and limitations. These include limitations in... Sample PDF
Human Factors and Culture
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Chapter 15
PACS Monitoring  (pages 244-263)
Carrison K.S. Tong, Eric T.T. Wong
The present study advocates the application of statistical process control (SPC) as a performance monitoring tool for a PACS. The objective of... Sample PDF
PACS Monitoring
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Chapter 16
Carrison K.S. Tong, Eric T.T. Wong
To illustrate the benefits of implementing QM in PACS, a successful case based on the Six Sigma approach is given below. It involves a project... Sample PDF
Quality Management Benefits
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Chapter 17
Epilogue  (pages 288-297)
Carrison K.S. Tong, Eric T.T. Wong
Today’s filmless radiology through PACS provides greater speed and superior image quality. However, when workflow is encumbered by inefficiencies... Sample PDF
Epilogue
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Appendix A
Appendix B
Appendix C
About the Authors