Design for PACS Reliability

Design for PACS Reliability

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.ch011
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Abstract

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 aviation, defence, telecommunication and healthcare, to name a few, computers have already assumed the most life-critical tasks. Unlike most human beings, computers seem to do their job pretty well, at most times and under all environmental conditions. Sometimes, however, for some reason, the fresh water supply in a city stops, the mainframe computer of an international security exchange centre malfunctions, or the satellite television goes out abruptly. Possible sources for such dissatisfactory performances are physical deterioration or design faults in hardware components. Fortunately in the 1950s and 1960s quite a number of reliability models were developed for hardware. Another major source for malfunctioning of computer systems is the presence of bugs in the software that controls the system. The modelling of software reliability was only begun in the early 1970s. This chapter presents a comprehensive approach to the development of a reliable PACS, which are capable of meeting the high-quality level required of mission-critical medical devices. To develop a preliminary design, the PACS team would begin with a system description and reliability evaluation of a baseline system, includ ing implementation of hardware redundancy, software provisions, and acceptance test. Through detailed system analyses and electrical, electronic and mechanical reliability studies, a final preliminary design can be derived. In this chapter the essential mathematical and statistical aspects of hardware and software reliability predictions are first presented, followed by a spreadsheet-based approach to model hardware and software reliabilities. A method of designing higher system reliability through parallel and cross-linked configurations is then given. Finally a brief case on the acceptance test of a PACS software is illustrated.
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Basic Concepts

Since the use of PACS raises both medical and social concerns, it cannot be instituted without addressing concerns related to the reliability and security issues. Reliability encompassed hardware and software reliability, including the retrieval of the previously obtained images. Reliability may be defined as the ability of a system to operate correctly according to its specification for a given time interval (Musa et al., 1987), under the precondition that the system operates correctly at the beginning of this time interval. Traditionally, system reliability is measured in terms of mean time between failures or the failure probability of a system function. To predict the reliability of component-based systems many methods have been proposed (Goseva-Popstojanova and Tivedi, 2001). The basic concept of these methods is to identify failure probabilities for each service of a component and determine the reliability of system functions based on the call sequences and dependencies between the low-level services and the specific system function.

PACS technologists are in many ways like soothsayers - they are expected to predict many things for the PACS: how many failures from this and that lot will occur within x number of years, how much of this and that lot will survive after x number of years, what will happen if a device is operated under these conditions, etc. Fortunately, they do not need any paranormal abilities to give intelligent responses to questions involving failures that have not yet happened. All they need is a good understanding of statistics and reliability mathematics to be up to the task.

In the present context, reliability is defined as the probability that software, component, device, or the entire PACS will perform its prescribed duty without failure for a given time when operated correctly in a specified environment. Reliability assessment, or the process of determining to a certain degree of confidence the reliability of a PACS, applies various statistical analysis techniques to analyze reliability data. If properly done, a reliability prediction using such techniques will match the survival behavior of the system, many years after the prediction was made.

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