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- Pacs Issues
- Systems and Components
- Pacs Experience I
- Invited Session: Siemens Experience with Pacs
- Invited Session: Pacs Experience at the University of Pittsburgh
- Invited Session: High-Resolution Displays
- Network Issues
- Pacs Experience II
- Invited Session: Clinical Evaluation of Pacs
- Invited Session: Planning, Expectation, and Image Evaluation for Pacs at the University of Iowa
- Image Filling and Retrieval Schemes
- Hardware and Software Issues
- Pacs Workstations
- Interfaces: Man and Machine
- Pacs Issues
- Image Filling and Retrieval Schemes
- Poster Session
- Implementation Experiences of the Commview System Pacs Applications
- Invited Session: Siemens Experience with Pacs
- Pacs Experience I
- Invited Session: Siemens Experience with Pacs
- Invited Session: Clinical Evaluation of Pacs
- Poster Session
- Interfaces: Man and Machine
- Poster Session
- Systems and Components
- Poster Session
- Implementation Experiences of the Commview System Pacs Applications
- Poster Session
- Image Filling and Retrieval Schemes
- Poster Session
Pacs Issues
Cost analysis of film image management and four PACS systems
David Volk Beard,
Deniese M. Parrish,
Daniel Stevenson
Show abstract
Picture Archive and Communication Systems (PACS), which allow the electronic acquisition, storage,
transportation, and viewing of medical images, hold the eventual promise of reduced costs, improved
image-management logistics, and ultimately, improved patient care. But at what point in the future will
PACS really cost less than film-based image management for a given hospital size; and how are these
costs affected by the choice of the digital communication network?
To address these questions, a static differential cost model has been constructed. Four PAC systems
based on different speed networks as well as film, were considered for five different sized hospitals
and two time periods. Based on the assumptions outlined, high-speed-network PACS (greater than
150 Mbps) are less costly than those based on low-speed networks for hospitals generating more than
15,000 procedures per year starting in 1995. Further, even though all possible PACS cost savings
were not considered, high-speed network PACS appear to be less costly than film for hospitals larger
than 30,000 procedures in 1995 and larger than 15,000 in 2000, while low-speed-network PACS
should cost less than film for 60,000 and 30,000 procedure hospitals in 1995 and 2000respectively.
High-resolution workstations for primary and secondary radiology readings
Ricky K. Taira,
Margaret A. Simons M.D.,
Mahmood Razavi M.D.,
et al.
Show abstract
We have implemented two high resolution workstations within our pediatric radiology PACS
module: a two-monitor 2K x 2K station and a six-monitor 1K x 1K station. The 2K x 2K workstation is
under evaluation for primary reading of pediatric radiographs from a computed radiography unit.
System implementation and evaluation methods are described. Operational efficiency measures of both
film and digital systems are reported. This study is our first attempt to integrate a primary viewing
station into a busy clinical environment. The 1K x 1K workstation is available 24-hours a day, 7 days a
week for fast reviews by referring physicians. Images from a compated radiography system are
available at the workstation in about 8 minutes. A digital voice reporting system is being developed to
communicate radiology reports from the 2K x 2K workstation to the 1K x 1K secondary review station.
PACS experience at the University of Hokkaido Medical School
Goro Irie,
Kazuo Miyasaka,
Kenji Miyamoto,
et al.
Show abstract
Seven months experiences of a filmless PACS (named HU-PACS) which covers
Radiology, Orthopedic, Internal medicine and General Surgery departments are
reported. The PACS has only 20 Image terminals but handles more than 50% of
images produced which is about 1000 images per working day.
Physicians of the departments have many criticisms and opinions on the PACS
but generally speaking it is well accepted and inspiring the physicians to
improve the PACS in its image quality and other functions instead of being
discarded. Preliminary clinical assessment are performed and reported also.
Systems and Components
Practical experience with PACS: benefits and pitfalls
Walter Ukovich,
Ludovico Dalla Palma,
Fulvio Stacul,
et al.
Show abstract
Since September 1988 a PAC System (CommView by AT&T and Philips) is in operation
in the Radiology Department of the University Hospital of Trieste, Italy.
A research project is presently in progress aiming at providing factual evidence
for the evaluation of this kind of systems as far as operational, technical,
clinical and economic aspects are concerned.
The general approach to this research consists in implementing and monitoring
a PACS in a stepwise way, starting with an "entry-level" system
With respect to our actual experience we propose a multi-attribute approach
to the problem of justifying PACS, thus classifying attributes into three broad
classes: operational, clinical and economic.
For each of the relevant problems we distinguish what could be expected in
general, what we actually found in practice and what we suppose to do in the
future.
Justifying PACS turns out to be a difficult task. Within a longer horizon,
a horizontalintegration within the Radiology Department and among different
Radiology Departments appears to open the more effective perspectives.
Development and implementation of ultrasound picture archiving and communication system
Wolfram S. Weinberg,
Franklin N. Tessler,
Edward G. Grant,
et al.
Show abstract
The Department of Radiological Sciences at the UCLA School of Medicine is developing an archiving and
communication system (PACS) for digitized ultrasound images. In its final stage the system will involve the acquisition
and archiving of ultrasound studies from four different locations including the Center for Health Sciences, the Department
for Mental Health and the Outpatient Radiology and Endoscopy Departments with a total of 200-250 patient studies per
week. The concept comprises two stages of image manipulation for each ultrasound work area. The first station is located
close to the examination site and accomodates the acquisition of digital images from up to five ultrasound devices and
provides for instantaneous display and primary viewing and image selection. Completed patient studies are transferred to a
main workstation for secondary review, further analysis and comparison studies. The review station has an on-line storage
capacity of 10,000 images with a resolution of 512x512 8 bit data to allow for immediate retrieval of active patient studies
of up to two weeks. The main work stations are connected through the general network and use one central archive for long
term storage and a film printer for hardcopy output. First phase development efforts concentrate on the implementation and
testing of a system at one location consisting of a number of ultrasound units with video digitizer and network interfaces
and a microcomputer workstation as host for the display station with two color monitors, each allowing simultaneous
display of four 512x512 images. The discussion emphasizes functionality, performance and acceptance of the system in the
clinical environment.
MRI simulator: a teaching tool for radiology
Debra A. Rundle,
Sheel Kishore,
Sridhar B. Seshadri,
et al.
Show abstract
The increasing use of magnetic resonance imaging (MRI) as a clinical modality has put an enormous
burden on medical institutions to cost-effectively teach Mill scanning techniques to
technologists and physicians. Since MRI scanner time is a scarce resource, it would be ideal if the
teaching could be effectively performed off-line. In order to meet this goal, the Radiology Department
has designed and developed a Magnetic Resonance Imaging Simulator. The Simulator in its
current implementation mimics the General Electric Signa scanner's user-interface for image acquisition.
The design is general enough to be applied to other MRI scanners. One unique feature
of the simulator is its incorporation of an image-synthesis module which permits the user to derive
images for any arbitrary combination of pulsing parameters for spin-echo, gradient-echo, and inversion
recovery pulse sequences. These images are computed in five seconds. The development
platform chosen is a standard Apple Macintosh-Il computer with no specialized hardware peripherals.
The user-interface is implemented in HyperCard. All other software development including
synthesis and display functions are implemented under the MPW 'C' environment. The scan parameters,
demographics and images are tracked using an Oracle database. Images are currently
stored on magnetic disk but could be stored on optical media with minimal effort.
Pacs Experience I
Management of ultrasound images by a picture archiving and communications system
Robert H. Choplin M.D.,
Johannes M. Boehme,
Neil T. Wolfman,
et al.
Show abstract
Since October, 1988, a picture archiving and communications system has been our
primary means of managing ultrasound images. The ultrasound area was selected
because of satisfactory image resolution with PACS, relatively low volume (18-20 cases
per day), and minimal clinician request for the images. We have performed over 6,000
examinations, comprising over 50,000 images during this time period. The images and
examination reports, stored on optical disks, are available on line for one week before
removal to shelf archiving. When shelf archived studies have required de-archiving,
most have been retrieved within five minutes. Rapid, reliable image acquisition allowed
for decrease in the study performance time. Display monitor illuminance stability
eliminates density variation associated with improper exposure of films. Immediate
availability of images makes possible on-line monitoring of technologist performed cases.
No images have been lost. Technical problems have included image degradation
because of pixel shift artifact, hardware and software failure, and duplicate entry of
patient demographic data. Despite rapid initial display and review, subsequent image
review is 6-10 times slower than with film based studies. If PACS are to succeed,
automatic archiving and de-archiving, improved system reliability, and improved speed
of display must be developed.
PACS system design, implementation, and evaluation in a trauma center
Robert E. Gold M.D.,
Helen T. Winer-Muram,
Scott L. Baum,
et al.
Show abstract
Although trauma has been recognized as the third leading cause of death overall in the United States, it is the leading cause of death in persons less than 40 years of age. There are approximately 150,000 trauma deaths per year. About 50,000 of these occur on the highway, with victims suffering severe multiple system injury. For every death, 2-3 patients suffer major long-term disability. An important estimate states that one in four of these deaths could be prevented1. With this unfortunate fact in mind, trauma systems have been developed across the country over the past decade. A trauma system consists of 1) a sophisticated prehospital system with paramedics initiating resuscitation and rapid transport; 2) on-line communication networks linking prehospital personnel with physicians in trauma centers who provide medical control; and 3) the trauma center, which acts as the hub of the system by coordinating the prehospital efforts and providing definitive trauma care. The trauma center concept has been developed and defmed by the American College of Surgeons, which established three tiers: Levels I, II, and III, with the most severely injured patients being triaged to Level I institutions. Since death and major disability occur within a short time following injury in those patients, diagnosis and therapy must be both simultaneous and expeditious. This is accomplished by having surgeons--trauma surgeons, neurosurgeons, orthopedic surgeons and anesthesiologists--and operating room teams present in the hospital at all times. A level I trauma center recreates, in part or in whole, a hospital environment focused on a limited spectrum of disease. All the problems in medical care related to imaging that are experienced in the trauma center also exist throughout the remainder of the hospital system. However, due to the speed of health care delivery and the concentrated focus of multiple surgical subspecialists and radiologists on the same small number of medical images the problems become severely exacerbated. Virtually all of the most serious problems related to imaging in a level I trauma center can be resolved with digital acquisition and storage of conventional images combined with transmission of already digital images (CT scans) to a central display location. Additional benefits can be expected with the provision of remote access to images from intensive care units and operating rooms and rapid transmission of images to the ShockfTrauma section where the earliest and most intense medical care is administered. Consequently, a PACS system was installed at the Regional Medical Center at Memphis. Installation was completed in the first week of December, 1989 and the system is currently being phased into operation, and evaluated.
Initial experience with a radiology imaging network to newborn and intensive care units
Show abstract
A digital image network has been installed in the James Whitcomb Riley Hospital for Children on
the Indiana University Medical Center to create a limited all digital imaging system. The total system
is composed of commercial components, Philips/AT&T CommView system, and connects an existing
Philips Computed Radiology (PCR) system to viewing workstations located in the intensive care unit
and the new born nursery.
The purpose and design of the system is to input the portable chest images from the PCR system,
and to display these images at the remote workstations on high resolution monitors for direct viewing
by referring clinicians, thus eliminating some of their visits to the radiology department three floors
away. The design criteria includes the ability to centrally control all image management functions on
the remote workstations to relieve the clinicians from any image management tasks except for
recalling patient images.
The principal components of the system are the Philips PCR system, the acquisition module (AM),
and the PCR interface to the data management module (DMM). Connected to the DMM are a
display workstation (DW), a optical disk drive, and a fiber optic to ethernet gateway. The ethernet
link is the network connection to the two results viewing stations (RVS) located approximately 100
meters from the DMM. The DMM acts as an image file server and image archive device. The
DMM manages the image database and can load images to both the DW's and the two RVS's.
The system has met the initial design specifications and can successfully capture images from the PCR
and direct them to the RVS's. Additional studies are beginning to determine the optimal image
management procedures such as when to archive and purge images from the DMM.
Invited Session: Siemens Experience with Pacs
Practical experience from Siemens PACS installations
Christian F. C. Greinacher,
Eric F. Bach,
Matthias Herforth,
et al.
Show abstract
Experience gained from Siemens PACS installations since 1986 has been of great value and
has lead to a continuous upgrading culminating in our today's products. Valuable
information not only on technical aspects but also experience in PACS project engineering and
operating a PACS has been acquired from a manufacturer's point of view. It might supplement
what the PACS users are reporting on their individual results.
Invited Session: Pacs Experience at the University of Pittsburgh
Subjective perceptions of and attitudes toward primary interpretation of x-ray images in a PACS environment
Cynthia A. Britton M.D.,
Jules H. Sumkin M.D.,
Hugh D. Curtin,
et al.
Show abstract
As part of a multi-project program, we are conducting a number of studies on the
implementation and use of digital radiology in the modern radiology environment. In
several of our completed studies, 10 participating radiologists have each been asked
to view and interpret 300 or more posteroanterior chest cases, presented on both
conventional film and on a high-resolution workstation. Because we believe that
radiologists' subjective acceptance of new uses of the digital modalities is important
if these techniques are to be more widely utilized, we administered a comprehensive
questionnaire to these radiologists to examine their attitudes regarding use of the
workstation vs use of film. General adjustment to the digitial modality, personal
comfort levels, and perceptions about time required for and resulting accuracy of
readings, as well as advantages and disadvantages of the digital system were examined.
In general, the radiologists in this study felt slightly less comfortable using the
workstation than using film, although they found adjustment to the workstation to be
fairly easy. The most important advantage of the workstation was thought to be the
ability to control contrast and brightness; the most important disadvantage, that
interpreting from the workstation was more tiring than interpreting from conventional
film when comparable numbers of images (50) were interpreted in a single reading
session.
Incorporation of a clinical history into the interpretation process in a PACS environment
Lawrence A. Cooperstein,
Barbara C. Good,
Linda M. Miketic,
et al.
Show abstract
In a large-scale, multi-reader study to investigate questions surrounding the
issue of the implementation of picture archiving and communications systems (PACS)
into the modern radiology environment, we examined the effect that the incorporation
of a clinical history into the reading process would have on levels of diagnostic
accuracy. Because we wanted to test the inclusion of the clinical history in an
environment as close to that of the clinical situation as possible, we defined
"history" to be a concise, objective, and potentially computer-extractable version of
what appears in the patient records, including a statement from the referring
physician when this is available. In a series of studies, four radiologists
interpreted 247 posteroanterior normal and abnormal chest images on conventional film
both with and without accompanying patient histories; five radiologists read the same
number of images presented on a high-resolution video workstation with and without
clinical histories. There were no significant differences (p = .05) in diagnostic
accuracy rates with or without clinical history for either the film or the workstation
in cases of interstitial disease, nodules, or pneumothorax. Diagnostic accuracy for
the radiologists as a group was not affected by the presence of the clinical history.
We concluded that for the interpretation of these abnormalities, the incorporation of
clinical history with images in the PACS environment should not be a major goal.
Implementation of a high-resolution workstation for primary diagnosis of projection radiography images
Show abstract
We designed and implemented a high-resolution video workstation as the central
hardware component in a comprehensive multi-project program comparing the use of
digital and film modalities. The workstation utilizes a 1.8 GByte real-time disk
(RCI) capable of storing 400 full-resolution images and two Tektronix (GMA251) display
controllers with 19" monitors (GMA2O2). The display is configured in a portrait
format with a resolution of 1536 x 2048 x 8 bit, and operates at 75 Hz in a noninterlaced
mode. Transmission of data through a 12 to 8 bit lookup table into the
display controllers occurs at 20 MBytes/second (.35 seconds per image). The
workstation allows easy use of brightness (level) and contrast (window) to be
manipulated with a trackball, and various processing options can be selected using
push buttons. Display of any of the 400 images is also performed at 20MBytes/sec (.35
sec/image). A separate text display provides for the automatic display of patient
history data and for a scoring form through which readers can interact with the system
by means of a computer mouse. In addition, the workstation provides for the
randomization of cases and for the immediate entry of diagnostic responses into a
master database. Over the past year this workstation has been used for over 10,000
readings in diagnostic studies related to 1) image resolution; 2) film vs. soft
display; 3) incorporation of patient history data into the reading process; and 4)
usefulness of image processing.
Statistical issues in ROC curve analysis
Howard E. Rockette,
Nancy A. Obuchowski,
Charles E. Metz,
et al.
Show abstract
Using simulation studies and the data obtained from our clinical investigations, we are comparing some of the techniques commonly employed in ROC analysis.
The general areas of our investigation include estimation of the area under the
ROC curve and its associated standard error, comparison of the areas under two ROC
curves, and simultaneous comparison of the areas under more than two ROC curves.
For single ROC curves, maximum likelihood estimation based on the binormal model
is being compared to the approximate area obtained using the Wilcoxon Statistic.
Standard errors obtained from classical asymptotic theory are being evaluated and
compared to standard errors based on jackknifing. With regard to the task of
assessing differences in the diagnostic accuracies of two systems, our investigations
have compared the maximum likelihood estimation method to a nonparametric
method based on the Wilcoxon Statistic, focusing primarily on correlated observations, e.g., from readings of different modalities' images of the same patients.
Extensions of existing methodology to the problem of comparing ROC areas from more
than two modalities are being addressed as well as problems associated with the
incorporation of multiple readers.
Primary diagnosis of chest images in a PACS environment
B. Simon Slasky M.D.,
Marc S. Rosenthal,
Carl R. Fuhrman,
et al.
Show abstract
In this study, we used a high-resolution workstation (1536x2048) with window
width (contrast) and level (brightness) manipulations available to test diagnostic
accuracy rates of seven experienced radiologists on 300 posteroanterior chest
images in a clinically simulated environment. Observer performance was assessed
by receiver operating characteristic analysis, and the results were compared to
performance when the same cases were interpreted by the same radiologists using
conventional film. Efficiency on the workstation was comparable to, if not better
than, that with the conventional film, but accuracy indices (Az) for the detection
of interstitial disease and pneumothoraces were lower for the workstation than for
conventional film. Since window width and level did not compensate for the lack
of resolution, we then examined in a following study the effects of different
processing options (reverse mode, unsharp masking) on diagnostic accuracy. These
image processing options did not significantly improve readers' performance.
Training observers for receiver operating characteristic studies
William H. Straub M.D.,
Howard E. Rockette,
Jill L. King,
et al.
Show abstract
In an ongoing, multi-reader, multi-project program dealing with the
interpretation of radiological images, we have examined several issues of methodology
which have not as yet been addressed that may impact on the determination of reader
performance as measured by receiver operating characteristic (ROC) analysis. Among
these are issues associated with the training of observers prior to such studies. We
employed three types of observer training that we found to be necessary for the
successful performance of such studies: 1) a general instructional session for
observers on the study protocol and system operation; 2) practice with an interactive
computerized feedback teaching file that demonstrates the imaging systems and
familiarized readers with an idea of the types of cases that were used in the study
along with their correct diagnoses; and 3) training sessions in which readers were
taught the manner in which to distribute answer ratings over an ordinal confidence
scale. The possible effect of such types of training on the performance and results
of ROC studies should be carefully considered prior to their commencement.
Invited Session: High-Resolution Displays
Experience with high-resolution digital gray-scale display systems
Samuel J. Dwyer III,
Glendon G. Cox,
Larry T. Cook,
et al.
Show abstract
High resolution gray scale displays are being evaluated for the display of 2K x 2K x 12 bit
digital images. A comparison has been analyzed for conventional chest radiographs,
digitized chest radiographs (2K x 2K x 12 bits) printed on laser film, and a high resolution
(2K x 2K x 12 bits) gray scale display. An initial study has been conducted comparing
computed radiography laser printed films and an interactive 1K x 1K x 12 bit display.
Network Issues
ISDN: early experiments as a wide-area extension to LAN-based PACS
G. James Blaine,
Roy C. Ferguson,
James W. Studt,
et al.
Show abstract
An Integrated Services Data Network test configuration, developed in collaboration with SBC Technology Resources
Inc., has been utilized to gain experience with both hardware and software interface isssues relevant
to wide-area extensions of PACS. Example workstations capable of inquiry and display of radiological information
have been interfaced to the ISDN trial network and tested. A DEGnet router was used to interface
our Ethernet-based PACS to an ISDN network. Average throughput rates of approximately 60Kb/s for the lB
(64Kb/s) channel and 120Kb/s for the 2B (l28Kb/s) channel were measured. Results were obtained for both
embedded and external ISDN terminal adapters.
Network data rate requirement analysis for picture archiving and communication systems
Akihiro Toshimitsu,
Yuki Fukushima,
Kiyoshi Tawara,
et al.
Show abstract
In this paper, the PACS network data rate requirement in a
radiology department is discussed. The network data transmission
rate under real data traffic in a medium-size hospital is
evaluated using a simulation study. The network is assumed to be
a circuit switching network. A preloading system, in which each
workstation has local storage to store the next procedure, is
assumed, and the network transmission rate which satisfies the
response time of this system is obtained.
Integrated network for medical imaging research
G. Allan Johnson,
Harrell G. Chotas,
Steven C. Suddarth,
et al.
Show abstract
There are a number of generic problems that researchers in medical imaging have in common. For example, researchers in MR, CT, PET, SPECT, DSA, and digital radiography all need to display and window digital images. We describe here an integrated network with tools applicable to all of the current areas of medical imaging that enable researchers at Duke to share resources and solve software and hardware problems in a unified effort. We will show examples where efforts in a specific area f imaging research can be readily applied in new ways to different imaging modalities through the facilities provided in this integrated approach. We will point out some of the problems and opportunities in the research environment that are different from those encountered in clinical PACS systems.
Performance evaluation of a picture archiving and communication system using stochastic activity networks
Ralph Martinez,
William H. Sanders,
Yasser H. Alsafadi,
et al.
Show abstract
The concept of picture archiving and communication systems (PACS) is now widely accepted in the medical
community. In order to bring the concept to reality, however, innovative designs and implementations are needed.
One such design is a fiber optic star based PACS, conceived by the University of Arizona and Toshiba corporation.
This PACS network is based on a multiplexed passive star local area network with wavelength-division multiplexing
to provide separate logical channels for transfer of control and image data. The system consists of an Image-Network
(INET), for image transfer at a rate of 140 Mbps, and a Control-network (CNET), operating at 10 Mbps, for
mediating the flow of image transfers. INET is a circuit switched network where a network supervisor grants users
permission to transfer images over it, while CNET employs the CSMA/CD protocol for bus arbitration. Before such a
system can be deployed, an accurate evaluation study must be carried out to estimate its performance characteristics.
Such evaluations are complicated both by the complexity of the PACS itself and the varied demands that are placed
on such a system. An novel approach based on siochastic aciiviiy neiworks, a stochastic extension of Petri nets, is
useful in this regard. Stochastic activity networks were used to develop a detailed model of the command and image
channels. The performance of the system was then evaluated under realistic workload conditions. In particular, we
were able to estimate a number of important performance variables including the image response time, command
channel delay, and queue length each type of node and the network supervisor. The results 1) show that stochastic
activity networks are an appropriate model type for evaluating picture archiving and communication systems, 2)
delineate the workload conditions under which PACS may effectively operate, and 3) show that even when these
conditions are exceeded, the command channel load remains extremely light. Results of this type are useful both to
designers of other PACS networks and those interested in this particular PACS design.
Pacs Experience II
Present status of PACS at Kyoto University Hospital: image workstation for clinical education
Kotaro Minato,
Masaru Komori,
Yoshihisa Nakano M.D.,
et al.
Show abstract
The PAC system: KIDS (Kyoto University Hospital Image Database and Communication
System) has been expanded to include several major digital imaging modalities such
as X-ray CT, MRI, DSA and CR. The fiber optic high-speed local area network and the
workstation with quick image handling are newly designed. The system (new KIDS) is
intended to achieve a film-less environment in the department of radiology and to
evaluate the feasibility of a hospital-wide PAC system. The present status of the
system at the end of 1989 including a image workstation installed in a lecture hall
for clinical education is described.
Performance of a partial PACS and its application to the development of a fully integrated digital medical imaging department in a community hospital
Josip Nosil,
Duncan L. Scobie,
Gerald C. Justice,
et al.
Show abstract
Victoria General Hospital, which is a part of the Greater Victoria
Hospital Society, is a 443 bed community hospital with a full-service
medical imaging department that includes MRI. In August 1987, four
rooms (chest radiography, GI fluorography, CT, and cardiac angiography)
were connected to a Picture Archive and Communications System (PACS).
We present the experience gained from two years of study with this
prototype PACS and briefly describe its hardware and software
configuration. Reported in detail is the measured image transfer
performance of the PACS for each of the four image sources.
Conventional films require more than 150 seconds from exposure to film
availability for reporting. Using PACS, chest and GI images take 77
seconds per image from exposure to viewing, 31 secs for CT, and 40 secs
for general angiography. The elapsed times with PACS between the
various software processes for each modality, and those needed to set
up image archive folders are detailed. The present imaging equipment
at VGH, a typical community hospital, is specified and is to be
integrated into a department-wide PACS. Required PACS performance
levels relative to the clinical demands are described, and compared
with the current PACS.
The information and experience acquired by testing the VGH PACS has
been used in the planning of the full implementation of PACS at VGH
(ref. 10. Fisher et al). The next phase (3C) of PACS implementation
is described.
Validating a simulation: comparison of a PACS network model of ultrasound image acquisition with actual performance
Show abstract
In expanding our image management and communications system (IMACS) to include a new machine in the
Ultrasound Section, we first modeled the impact of attaching the unit to either of our two acquisition modules (AM). Using
the software package available to us, we could predict image queue lengths and average image waiting times (before
transmission to the central archive). The AMs have attached a variety of devices with differing image production loads. The
modeling allowed us to select the AM which would be least impacted (in terms of resoponse time to the devices sending data
to the AM) by the added ultrasound machine.
We found that though the input response times would not change much with the ultrasound machine connected to
either AM, there was a significant impact on the predicted output queue length, with the more heavily loaded AM suffering
larger increases in output queue dwell time if the new machine were connected to it. Based on these results, we elected to
redistribute the AM loads, and connect the ultmsound machine so as to maintain a relatively balanced load.
We tested certain parameters of the model by measuring input and output response times ofan AM under different,
artificially induced, acquisition loading. The changes predicted by the model agreed with those measured in order-of magnitude
terms.
Invited Session: Clinical Evaluation of Pacs
Clinical evaluation of PACS: modeling diagnostic value
Harold L. Kundel,
Sridhar B. Seshadri,
Ronald L. Arenson
Show abstract
A model is presented for evaluating the diagnostic value of an imaging
system in clinical use. It is site-specific and includes thedistribution of
diagnostic findings, diagnostic accuracy, the importance of the test
outcomes to the physician, and the timeliness of information delivery.
Multi-institutional studies of diagnostic imaging: potential methodology for PACS evaluation
Constantine Gatsonis
Show abstract
Abstract not available.
Invited Session: Planning, Expectation, and Image Evaluation for Pacs at the University of Iowa
Perceptions of PACS
Wilbur L. Smith,
Elizabeth Altmaier,
Linda Berberoglu,
et al.
Show abstract
Picture Archiving and Communication Systems (PACS) represent an enormously
expensive technological innovation which has the potential to alter the way in
which radiology is practiced. In a 1985 survey of radiologists and radiology
administrators, over a quarter of those individu1s expected to have some
component of an operational PACS system by 1986. The survey respondants
perceived advantages including fast access to files, multiple user simultaneous
access to films, and possibly secondary benefits in accuracy in diagnosis and
improved communications.
Progress in widespread PACS implementation has considerably lagged the rate
anticipated in the 1985 study. In order to evaluate the current expectations of
PACS and contrast them to the earlier enthusiasm we have undertaken this study
of the current perceptions of PACS among both radiologists and clinicians.
Planning, expectation, and image evaluation for PACS at the University of Iowa hospitals and clinics
Show abstract
Our strategy in studying PACS is to evaluate its clinical implementation working
with equipment supplied by an established manufacturer. Fiscal and personnel
resources required to design and integrate the hardware components and operational
software to develop a functional PACS precluded a bottom up development approach at
our institution. Imaging equipment vendors possess more abundant design development
resources for this task and therefore can support a more rapid development of the
initial components of PACS.
For this reason we have chosen to serve as a beta test site to study the viability
of the basic PACS components in a clinical setting. Our efforts primarily focus
on: (1) image quality; (2) cost effectiveness; (3) PACS/HIS/RIS integration;
(4) equipment and software reliability; and (5) overall system performance. The
results of our studies are shared with the vendor for future PACS development and
refi nement.
To attain our investigational goals we have formed an interdisciplinary team of
Radiologists, Perceptual Psychologist, Economist, Electrical and Industrial
Engineers, Hospital Information System personnel and key departmental
administrative staff.
For several reasons Pediatric Radiology was targeted as the initial area for our
PACS study: a small area representative of the overall operation,tight operational
controls and willingness of physicians. We used a step-wise approach, the first step
being the installation of PACS exclusively within the physical confines of Pediatric
Radiology.
Image Filling and Retrieval Schemes
Methods to prefetch comparison images in image management and communication system
Kenneth Levin,
Robert Fielding
Show abstract
A high-level description of a system to pre-fetch
comparison radiographs in an Image Management and
Communication System (IMAC) is presented. This rule based
system estimates the relevance of previous
examinations for comparison to the current examination
arid uses this determination to pre-fetch comparison
studies. A machine learning module should allow the
system to improve its skill in pre-fetching
examinations for each individual radiologist. This
system could be tailored to fit the desires of
individual radiologists.
Image archiving by content: an object-oriented approach
Petros G. Kofakis,
A. Karmirantzos,
Y. Kavaklis,
et al.
Show abstract
In this paper we present initial work on the design and implementation of an image database system for medical images. The objective
of this project is the development of an environment that will permit the quick and intelligent access of images using their content. An
image database is a complex system consisting of many components that must be unified and integrated. These are the image analysis
component that derives a representation of the stored images, the database component, and the user interface component. This paper focuses
primarily on the justification of the design decisions, an illustration of the major features of such a system, and a requirements definition for
its implementation. An object-oriented approach is proposed which meets these requirements. The capabilities of an object-oriented data
model are demonstrated and possible extensions, needed to meet the data modeling requirements, are discussed.
Personal digital image filing system
Show abstract
We are developing a personal image filing system as an alternative method of archiving radiolOgical images. The
system can be configured with three popular computers as host: IBM PC/AT, Macintosh II, and SUN. The images are
archived on the 3.5-inch optical disk and can be retrieved by any of the host computers for display.
Development of new method image diagnosis through hybrid PACS -- with a special concern to a dynamic image
Tomoho Maeda,
Hitoshi Nishimoto,
Shoji Yoshida,
et al.
Show abstract
We conceived a hybrid PACS which combines analogue and digital elements where it is
required. We experimented a clinical application of the dynamic image utilizing the
analogue element which is a feature of the hybrid PACS. With the analogue optical
disk, dynamic image acquisition of 30 frames per second is possible and image
recording is also possible with any modality of X-ray fluoroscopy function. In
addition, X-ray dose to the patient is one-fifth to one-tenth compared with the
conventional cine filming method while its still image is clear and a data
acquisition to the PACS is easy. We applied this system to the areas of the
otorhinolaryngology, orthopaedics and respiratory disease and could perform a various
analysis of the disease status under natural conditions, also we found that this
system is useful for judging an effect of a treatment as well as jugding a functional
recovery after an operation and an effect of a rehabilitation. We are also planning
to extend the application to the areas of the digestive system and the group
examination from now on.
Hardware and Software Issues
IBM Application System/400 as the foundation of the Mayo Clinic/IBM PACS project
Melvyn L. Rothman,
Richard L. Morin,
Kenneth R. Persons,
et al.
Show abstract
An IBM Application System/400 (AS/400) anchors the Mayo Clinic/IBM joint development PACS project.
This paper highlights some of the AS/400's features and the resulting benefits which make it a strong foundation
for a medical image archival and review system. Among the AS/400's key features are:
1. A high-level machine architecture
2. Object orientation
3. Relational data base and other functions integrated into the system's architecture
4. High-function interfaces to IBM Personal Computers and IBM Personal System/2s' (pS/2TM).
New AS/400-based PACS for MRI and CT
Richard L. Morin,
Glenn S. Forbes M.D.,
Dale G. Gehring,
et al.
Show abstract
Following our initial investigation of the utility and performance of an AS/400
based token ring network for MRI image archival, we have designed and embarked upon
a project to install multiple token ring networks at three physically separated
facilities connected with fiber optic communication to archive and display CT and
MRI image data. The system design will connect six MRI systems, six CT systems,
four optical storage systems, three image display systems, three radiology report
scanners, and a foreign archival system. Network communication and archival
functions will be managed by an IBM AS/400. Preliminary estimates indicate that
savings of media, space, and personnel as well as the additional benefit of online
reports with image data will enhance the quality and efficiency of clinical
practice.
Additionally, we are evaluating a medical image display system (MIDS) to be used
for on-demand image review, prefetched image review, and a potential replacement
for modality-specific physicians consoles. The MIDS workstation is a promising
addition to clinical practice both from the standpoint of an efficient means of
image review as well as image interpretation.
We consider this joint project to be an important step in the process of
understanding the impact and subsequent consequences of electronic image
transmission, information communication, and archival within a busy clinical
setting. Our performance and design criteria focus upon the impact of this system
on the clinical practice within radiology and the subsequent ramifications of PACS
throughout the institution.
Impact of node architecture on network performance
Fred W. Prior,
Klaus Niggenaber,
Shahram Khosravani,
et al.
Show abstract
The first parameter of interest in considering network performance is signaling rate. To understand end-to-
end image transfer rate, however, signaling rate is often the parameter of least importance. The basic
image transfer in a PACS is disk-to-disk or at best disk-to-memory. The real performance bottlenecks are
disk and system bus I/O rates, CPU and operating system efficiency in executing network protocols, and
throughput of network interface units. Except for issues of congestion, the end-to-end performance of a
100 Mbps FDDI net may not be significantly different from that of a 10 Mbps Ethernet.
The system architecture of workstations and storage nodes is the key to overall PACS network
performance. Simulation studies indicate that a high speed disk subsystem combined with an intelligent
network interface unit avoids the bottlenecks associated with conventional systems and can make use of
high bandwidth media such as broadband ISDN. Experience with a preliminary demonstration of
broadband ISDN connectivity as part of the Berlin Communications (BERKOM) project will be
presented.
FEASIBLE software supports the ROC evaluation of digital imaging systems
Fenno P. Ottes,
Luuk Steenbergen,
Frits Hendrik Barneveld Binkhuysen,
et al.
Show abstract
A software package has been developed to aid psychophysical studies on diagnostic image quality. The
program, called FEASIBLE, supports all phases of experiments to evaluate the diagnostic quality of
PACS components, image acquisition and manipulation methods and display techniques. The software
allows the user to design any such an evaluation study, to perform an arbitrary number of
psychophysical sessions and to statistically analyze the collected data with the Receiver Operating
Characteristics (ROC) technique. Furthermore, the calculated ROC curves can be plotted in graphs to be
integrated in publications. Within the scope of the Dutch PACS project, a PACS research project jointly
carried out by the Utrecht University Hospital, BAZIS and Philips, FEASIBLE has been used to
investigate the diagnostic accuracy of the PACS prototype that was clinically evaluated. The package has
been sent - upon request - to more than 20 scientists in the field of radiological imaging. This paper
explains the backgrounds and the features of the latest version of the program, and the way to use it in
an actual ROC study.
Pacs Workstations
Clinical evaluation of PACS workstations: methodology and results
Show abstract
The University of Washington participated, during 1986-89, in a clinical evaluation of commercially available PAC systems
under the sponsorship of the MITRE Corporation (Contract N55-200). As part of this work, we developed a general approach
to the clinical evaluation of PACS workstations. This paper describes the approach and its application to a specific
workstation, the AT&T CommView Diagnostic Workstation.
Dedicated radiology viewing station for low cost and high performance
Show abstract
The functional requirements of a radiological viewing station has been determined by feedbacks
from radiologists. In this project, we incorporated all the functional requirements in a custom designed
display station with emphasis on affordablility and display speed. Utilization of the open architecture of
VME and VSB buses led to expandability of display screens, memory sharing, and availability of off-the-
shelf frame buffers.
Architecture for a PACS primary diagnosis workstation
Kaushal Shastri,
Byron Moran
Show abstract
A major factor in determining the overall utility of a medical Picture Archiving and Communications
(PACS) system is the functionality of the diagnostic workstation. Meyer-Ebrecht and Wendler [1] have
proposed a modular picture computer architecture with high throughput and Perry et.al [2] have defined
performance requirements for radiology workstations. In order to be clinically useful, a primary diagnosis
workstation must not only provide functions of current viewing systems (e.g. mechanical alternators
[3,4]) such as acceptable image quality, simultaneous viewing of multiple images, and rapid switching of
image banks; but must also provide a diagnostic advantage over the current systems. This includes
window-level functions on any image, simultaneous display of multi-modality images, rapid image
manipulation, image processing, dynamic image display (cine), electronic image archival, hardcopy
generation, image acquisition, network support, and an easy user interface. Implementation of such a
workstation requires an underlying hardware architecture which provides high speed image transfer
channels, local storage facilities, and image processing functions. This paper describes the hardware
architecture of the Siemens Diagnostic Reporting Console (DRC) which meets these requirements.
Operator interface design for a PACS primary diagnosis workstation
Rick H. Freeman,
Cynthia S. Neubecker,
Scott A. Keller,
et al.
Show abstract
One of the challenges to the PACS workstation designer is to cost effectively fulfill the range of
requirements from those of the entry-level system to those of the fully digital hospital. The workstation
must therefore support many of the functions of film-based image storage and image information
systems.
A primary diagnosis workstation must support rapid selection and viewing of patient examination
folders. The user must easily and rapidly sequence through a stack of examinations. Activities such as
printing films, archiving images, and retrieving older examinations must be initiated easily, without
interfering with the diagnostic use of the workstation. Some of these functions are executed by the
workstation itself while others are performed by service nodes on the PACS network. The
workstation's user interface must make the architecture of the system transparent, providing access to the
services while concealing the complexity of their accomplishment.
This paper discusses the approach taken to the user interface of a commercial PACS primary
diagnosis workstation. This workstation may be configured as an entry-level PACS or as a single
workstation in a very complex system. Local image storage, retrieval, archiving and display functions
will be described. Networking with modalities, image storage systems and image management systems
will also be discussed.
Interfaces: Man and Machine
Operator interface design considerations for a PACS information management system
James E. Steinke,
Kamal H. Nabijee,
Rick H. Freeman,
et al.
Show abstract
As prototype PACS grow into fully digital departmental and hospital-wide systems, effective
information storage and retrieval mechanisms become increasingly important. Thus far, designers of
PACS workstations have concentrated on image communication and display functionality. The new
challenge is to provide appropriate operator interface environments to facilitate information retrieval.
The "Marburg Model" 1 provides a detailed analysis of the functions, control flows and data
structures used in Radiology. It identifies a set of "actors" who perform information manipulation
functions. Drawing on this model and its associated methodology it is possible to identify four modes of
use of information systems in Radiology: Clinical Routine, Research, Consultation, and Administration.
Each mode has its own specific access requirements and views of information. An operator interface
strategy appropriate for each mode will be proposed.
Clinical Routine mode is the principal concern of PACS primary diagnosis workstations. In a full
PACS implementation, such workstations must provide a simple and consistent navigational aid for the
on-line image database, a local work list of cases to be reviewed, and easy access to information from
other hospital information systems. A hierarchical method of information access is preferred because it
provides the ability to start at high-level entities and iteratively narrow the scope of information from
which to select subsequent operations. An implementation using hierarchical, nested software windows
which fulfills such requirements shall be examined.
Teleradiology to the intensive care units at Shands Hospital
Edward V. Staab,
Peggy Mitchell,
Jon L. Williams Sr.,
et al.
Show abstract
The clinicians at Shands Hospital at the University of Florida were frustrated by the filmbased system, which served them in taking care of their patients in the Intensive Care Units (ICU). Frequently, they would come to the radiology department three to six floors below their respective ICU only to be stymied by the inability to find a study that was needed for patient care. This led to much consternation and outright animosity towards the personnel in the radiology department. On the other hand, the radiologists were exasperated by the missing films and lack of cooperation of the ICU team of physicians and nurses. The common denominator was an inefficient communications system for sending chest and abdominal films to the ICUs. A solution was proposed, tested, and installed by DuPont. Our initial experience with this system was reported.1 We have now modified and extended this system to all of the ICUs, which represents the basis for this report. The clinical review system (CRS) was initially placed in the medical ICU and very shortly thereafter expanded to serve all six ICUs at Shands Hospital. These include surgical, neurosurgical, cardiothoracic, pediatric and neonatal ICUs. Approximately 30,000 portable examinations are done each year in these areas.
Performance comparisons of image communication networks
Albert W. K. Wong,
Shyhliang A. Lou,
Brent K. Stewart,
et al.
Show abstract
We have evaluated the performance of Ethernet, Fiber Distributed Data Interface (FDDI) and Canstar Super 100
networks in a multimodal Picture Archiving and Communication System (PACS) environmenl image data transfer
rates were measured for SUN workstations and PC/ATs running TCP/IP communication protocols. The communication
between two computers was on a server-client basis and all transfer rates were measured between computer memories in
order to eliminate the bottleneck imposed by storage devices. Four test models were used to evaluate the performance of
the three individual networks: bidirectional, centralized parallel and relay models. This paper describes the methods of
network throughput evaluation using these four models and presents the resulting performance data for the three networks
tested.
Pacs Issues
Software considerations in the design of an image archive
Sridhar B. Seshadri,
Sheel Kishore,
Satjeet S. Khalsa,
et al.
Show abstract
The Radiology Department at the Hospital of the University of Pennsylvania
is currently expanding its prototype Picture Archiving and Communications
System (PACS) into a fully functional clinical system. The first phase of
this expansion involves three major efforts: the upgrade of the 10-Mbit
token-ring to an 80-Mbit backbone with associated sub-nets, the
implementation of a large-scale image archive, and, an interface between
the PACS and the Department's Radiology Information System. Upon the
completion of this phase, the PACS will serve the storage and display needs
of four MRI scanners and four of the Hospital's Intensive Care Units. This
paper addresses the implementation of a software suite designed to
duplicate and enhance conventional Film Library functions on a PACS. The
structure of an electronic 'folder' based upon the ACR/NEMA Digital Imaging
and Communication Standard is also introduced.
Image Filling and Retrieval Schemes
Providing image management and communication functionality as an integral part of an existing hospital information system
Ruth E. Dayhoff M.D.,
Daniel L. Maloney
Show abstract
The effective delivery of health care has become increasingly dependent on a wide range
of medical data which includes a variety of images. Manual and computer-based medical
records ordinarily do not contain image data, leaving the physician to deal with a fragmented
patient record widely scattered throughout the hospital. The Department of Veterans Affairs
(VA) is currently installing a prototype hospital information system (HIS) workstation network
to demonstrate the feasibility of providing image management and communications (IMAC)
functionality as an integral part of an existing hospital information system. The core of this
system is a database management system adapted to handle images as a new data type.
A general model for this integration is discussed and specifics of the hospital-wide network
of image display workstations are given.
Poster Session
Optimization of a PACS display workstation for diagnostic reading
K. G. O'Malley,
Stephen P. Ricca
Show abstract
The design of workstations for use in picture archival and communications systems (PACS) has
received a significant amount of attention; rightfully so, as it is the most noticeable element in such a
system. Various aspects of medical imaging workstations have been studied in detail, including feature
requirements, user interface, performance requirements, and other human factors considerations.
Experience during implementation of the CommView system PACS has shown that it is most
important to carefully consider the operational environment in which these workstations will be placed
to match the tasks and flow of information to, from, and within the workstation with the tasks and
flow of information in the traditional film-based environment. Equally important is the cost of such a
workstation. and the well - designed workstation is one that successfully matches the operational
environment at a reasonable price.
We describe in this paper the process undertaken to optimize a PACS workstation for the operational
environment of diagnostic reading and reporting. Operational models have been developed, through
interviews with and observations of users at Bowman Gray/Baptist Hospital Medical Center. Duke
University Medical Center. San Francisco VA Medical Center, and Georgetown University Hospital.
Hardware and software designs of the workstation were optimized to match the workstation to those
operational models, including matching the time intervals, and providing easy access to relevant exams
and to historical exams to be used for comparison.
Implementation Experiences of the Commview System Pacs Applications
Assessment of the integration of a HIS/RIS with a PACS
Betty A. Levine,
Seong Ki Mun,
Harold R. Benson,
et al.
Show abstract
The exchange of information between a Radiology Information System (RIS) and a PACS is essential to optimizing
the utility of a PACS. Some of the benefits awarded by implementing an interface include a reduction or elimination
of repetitious data entry, the availability of more accurate information on the PACS, a reduction in workload for the
technologists, registration clerks, transcriptionists, etc, and the availability of more accurate data for automating the
PACS. This paper discusses the Georgetown experience of interfacing an HIS/RIS and PACS, by describing the
development of the interface and its impact on clinical operations.
Optimization of image transfer from the central archive to workstations in a PACS
Jay J. D'Lugin,
Johannes M. Boehme,
Robert H. Choplin M.D.,
et al.
Show abstract
Despite the much-discussed advantages of the all-digital radiology department, the speed of electronic
display continues to be a major obstacle to its acceptance; physicians generally agree that sophisticated
workstation functionality cannot compensate for an interpretation environment that delays diagnosis.
Two design schemes have been devised and discussed at length at the Bowman Gray School of Medicine
(BGSM) that will improve the efficiency of image transmission significantly. The first of these is image
routing and pre-loading. The central archive can use information associated with each exam and a set of
rules to predict which workstations will be used to read the exam. The images can thus be sent
automatically before the physician arrives at the workstation to interpret a series of exams. The second
scheme, which is intimately associated with the first, allows a workstation to manage its own local disk to
remove copies of exams so that new ones may be pre-loaded. This disk management algorithm assigns priorities
to the exams based on their status in the acquisition/interpretation cycle and performs automatic
deletion as the workstation's disk reaches its capacity. The effect is a virtually limitless disk that eliminates
the time-consuming task of manual deletion and retrieval of images.
Invited Session: Siemens Experience with Pacs
Siemens experience in PACS
Charles L. Hall,
John H. Perry
Show abstract
Experience from ten years in Picture Archiving and Communication Systems has led to a clearer
understanding of the user, system, and component requirements for PACS, and the evolving market. This
paper reports on one manufacturer's considerations and experiences as a PACS supplier.
PACS: acquisition strategy, resources, and planning process
Robert E. Gold M.D.,
Gary N. Elledge,
Barney C. Lee,
et al.
Show abstract
The Regional Medical Center at Memphis (the MED), including the Presley Memorial Trauma Center (the Trauma Center) is a privately operated, county owned, partially public funded institution that contracts with the University of Tennessee, Memphis (UT,Memphis) for physician clinical services. For approximately the past eight years, the administration of UT,Memphis has encouraged and emphasized the development of "Information Technology". To that end, a number of initiatives were developed on the campus, ranging from the development of a service oriented computer science department and the installation of an extensive broad band cable network to the widespread distribution of personal computers amongst the faculty. More recently, UT,Memphis and Siemens Corporation, the vendor of the UT,Memphis Magnetic Resonance Imaging (MR.I) equipment, collaborated in creating a link between the MRI and a physician workstation located in the Imaging Section of the MED. The MRI is located approximately a half mile from the MED and the link was established over the university broad band cable network. From those beginnings, interest developed within the Department of Raliology in more fully exploring the current PACS technologies. However, a number of resources often associated with the current installation of PACS technologies were lacking at UT, Memphis. No research funds were available from the university or from the Department of Radiology. Until very recently, and well into the final stages of planning for PACS, no significant biomedical engineering resources were available on the campus. The Physics Section of the Department of Radiology was overextended in providing support for a variety of clinical sections of the Department of Radiology. It became apparent that the most appropriate financial support for a PACS system was through the resources of one of the hospitals associated with UT,Memphis and that a major portion of the required technical support would have to come from the vendor and the hospital.
Pacs Experience I
PACS: ugly duckling or swan?
Christian F. C. Greinacher,
Eric F. Bach,
Matthias Herforth,
et al.
Show abstract
PACS is a topic which has not yet been granted a Seal of Approval by Radiology. One
must only count the negative reports published to see that. A change of name from
PACS to Image Management, Archival and Communication Systems (IMACS) will
also not help the matter at the current stage of development. What is needed are clinical
demonstrations of the philosophy behind PACS and of the fact that it works today and is
not just an ugly duckling.
Invited Session: Siemens Experience with Pacs
Radiological image transfer and communication within the BERKOM/RADKOM project
Matthias Langer,
J. Hunger,
W. Zendel,
et al.
Show abstract
In this radiologic communication project two PAC-systems were
installed in two locations of one radiologic department of the
Rudolf Virchow University Clinic lying about 10 km apart. The
realisation of a well-operating PACS-to-PACS communication is
related to a fast image- and video- data transfer and a command processing
technic. The PACS-workstation has to enable the
manipulation and post-processing technics known from CT-, MR- and
DSA- imaging.
Invited Session: Clinical Evaluation of Pacs
Clinical evaluation of PACS: a transcript of Session 8
Show abstract
This session really had its genesis sometime ago when Ed Staab and I had a discussion about the problems of evaluating a PACS. A lot of what we had seen had related to technical evaluation or observer performance studies, and we think those studies are extremely important, but it looked like a lot of the radiology community was interested in going beyond those and looking at PACS as a whole and how it might impact patient care With that thought in mind we began planning the session. We saw a really excellent study by David Gur and his colleagues yesterday on some of the observer performance issues, perhaps the ultimate expression of observer performance studies in terms of evaluating film or digitized film versus CRT displays. As I said, our goal in putting this session together was to try to get some additional insight into clinical evaluation beyond the methodology used for observer performance studies. And perhaps looking at some long range issues that could potentially affect the clinical evaluation of PACS. In that regard I invited, and was happy to receive acceptances from, three speakers. There will be three papers in this session. Unfortunately the last one did not get printed. Harold Kundel and Constantine Gatsonis have their subject titles listed. The third speaker will be David Beard from the University of North Carolina who will be talking about "Is a Work Station as Good as Film?" I think you are in for a very interesting, and I hope thought-provoking session. With that, I would like to introduce Harold Kundel, a radiologist and Professor of Radiology at the University of Pennsylvania, who will speak about the impact of PACS on patient care, efficacy, and outcome studies.
Poster Session
Intelligent supporting system for image diagnostic workstation of PACS
Kazuo Aisaka,
Kazuko Terada,
Akihide Hashizume,
et al.
Show abstract
One of the key technologies in developing the picture archiving and communication system (PACS)is
the method of presenting pictures. The pictures must be of sufficient quality to enable diagnosis and
their presentation must be automatic so as not to interrupt doctors' concentration. The authors are
developing a diagnostic work station (WS) which can solve these problems. In this study, we experimented
on (1) a picture enhanement method for improving picture quality, and (2) a picture handling environment
for simplifying operation. The results suggest that the YS should possess the intelligence to free
doctors from complex operations.
Evaluation of a picture archiving and communication system with combined voice and data traffic
Yasser H. Alsafadi,
William H. Sanders,
Ralph Martinez
Show abstract
The importance of providing voice communication between picture archiving and communication system
(PACS) users has been realized by many researchers. In particular, voice communication can aid in the
diagnosis of a patient by geographically separated radiologists and physicians. The voice dialogue can
also be stored for later review. This work reports the results of a study to investigate the feasibility of
introducing packetized voice to a particular PACS network. It is based on a multiplexed passive star local
area network with wavelength-division multiplexing to provide separate logical channels for transfer of
control and image data. It consists of an image network (INET) for image transfer at a rate of 140 Mbps,
and a control network (CNET) operating at 10 Mbps, for controlling the flow of image transfers. The
CNET employs the CSMA/CD protocol for bus arbitration. Previous simulation studies have shown that
the CNET remains extremely underutilized even under conditions that overload the INET. This suggests
that the CNET could be used to carry packetized voice as well as the control data currently carried. Use
of the CNET for this purpose must be considered carefully, however, since the CSMA/CD protocol suffers
long packet delays at heavy loads. At an early design phase, detailed modeling can be used to determine
whether this will occur at various loads for this PACS. Stochastic activity networks provide the modeling
framework necessary to carry out a detailed evaluation of this type. In this research, we represent the
modified PACS network and the hypothesized voice, control, and image workload as stochastic activity
networks. We verify that the network can support packetized voice in CNET while providing a reasonable
service to control traffic.
Traffic between PACS and HIS/RIS: data or information?
Albert Reinder Bakker,
Herman Lodder,
Jef M.L. Kouwenberg
Show abstract
When studying the functions to be supplied by a PACS the need for a link with
the HIS/RIS turns out to necessary for two classes of reasons:
- the first class deals with the need to supply as much clinical information at
the workstations as possible. Whether this information is stored within the
HIS/RIS should be transparant to the user.
- modelling and simulation of PACS gives evidence that thetraffic load in a PACS
can only be handled adequately when the image management system can take into
account patient flow and patient medical story. As typical example can be
mentioned prefetching algorithms that take care of activation of images from the
archive before they are actually needed. The activation process is controlled by
events in the hospital that indicate an increased probability that these images
will be needed.
The first class of reasons lead in general only to use of data that in principle
can just be presented on the screen of the workstation. The PACS does not need to
be aware of the meaning of the data: no common understanding is necessary. So just
data can be transfered that will be presented in a transparant way.
The second class of reasons deals with data from the HIS/RIS that should be
understood by the PACS to be able to take the required action. So the meaning of
the data is to be known. In this second class we have to deal with exchange of
information while for the first class exchange just data is sufficient.
Since the concepts of PACS and HIS are to a large extent similar it is not evident
to which of the two certain functions will be assigned. This assignment of
functions is considered and some suggestions for implementation of a link between
PACS and HIS/RIS are given.
Advanced physicians workbench: an X-Windows-based workstation
Robert E. Braudes,
Kenneth E. Hauck,
Seong Ki Mun,
et al.
Show abstract
The Advanced Physicians Workbench (APW) is a radiology image management system
display workstation built upon two generally accepted software packages, namely the X Windows
System and the Informix database system. Two main purposes for the APW are: (1) to explore
the feasibility of building a PACS display station for referring physicians by means of
standardized application software development systems and (2) to investigate the use of
individual, independent windows for image display and manipulation.
Mayo/IBM PACS project: phase one description
Everett G. Brooks,
Melvyn L. Rothman,
Dale G. Gehring,
et al.
Show abstract
This paper provides a brief technical description of the Mayo/IBM Phase one PACS project. It covers
additions to the Phase Zero system which transforms the system from a prototype archival system into
an AS/400-driven, on-line, interactive, medical image review and archival system.
Free-response receiver operating characteristic analysis in medical imaging
Show abstract
Recently we have introduced a method for analyzing Free-response Receiver Operating
Characteristic (FROC) experiments. These differ from traditional ROC observer
performance experiments by allowing for multiple abnormalities and observer
responses per image, and by requiring correct localization for true positive events. We
introduced the Alternative FROC (AFROC) plot which is analogous to the ROC plot, and the
area under it, which is analogous to the area parameter of ROC methodology.
Subsequently we have extended the analysis with a new way of scoring FROC images,
termed AFROC analysis. This renders unnecessary the Poisson assumption used in the
earlier paper. We also introduced the Free-response Forced Error (FFE) experiment
which renders unnecessary the Gaussian distribution assumption of FROC and AFROC
analysis. FROC/FFE experiments performed with synthetic images (disk objects at random
locations on a noise background) which illustrate the FROC methodology are presented.
We wish to bring to the attention of PACS researchers that rather sophisticated efficacy
analysis, which has several advantages over the standard ROC approach, is made possible
through this methodology.
PACS for chest radiology
Paul S. Cho,
Albert W. K. Wong,
Denise R. Aberle,
et al.
Show abstract
We are developing a PACS module for thoracic radiology. The Chest PACS is composed of image acquisition
subsystem, PACS seiver, display workstation, and communication network The system design is complicated by the
clinicaldemandsfor high image quality on theprojectional images which implies a large amount ofdata to be transmitted,
stored, and displayed. This paperpresents the details of the system design.
Development of a prototype electronic alternator for DIN/PACS environment and its evaluation
Show abstract
A prototype electronic alternator (EA) has been implemented utilizing an advanced image processing workstation
and evaluated for its clinical acceptability as a primary diagnostic workstation. The workstation is based on a
PIXAR II image computer and is a node on the University of Washington Digital Imaging Network and Picture
Archiving and Communications System (DIN/PACS, hereafter PACS). The goals of this study are to utilize the
unique features ofthe workstation (large image memory, a high-speed parallel transfer disk (PTD), and a 2560 x 2048
high-resolution image monitor) to demonstrate the feasibility of a limited model of the EA as a primary diagnostic
workstation in the PACS environment, to evaluate its capability in image viewing and diagnosis, and to assess the
feasibility of an icon-based user interface to select and rearrange images on the monitor. In this paper, various
characteristics of the prototype EA such as image display and processing performance, image storage capacity,
and functional specification as well as the results of a clinical evaluation are presented. The main emphasis of the
clinical evaluation was on system speed, image quality, and user preference for an icon-based user interface.
Two chip ACR-NEMA datalink/physical layer implementation
Wayne Thornton DeJarnette
Show abstract
A high performance ACR-NEMA computer interface board for the IBM PC/AT bus will be
described. The interface board (AT/NSIF) implements the transport/network thru
physical layers of the R-NEW standard. The interface board also supplies a
session layer mapping function. The session layer mapping function, the
transport/network layer protocol and the datalink layer protocol are implented via
an on board microprocessor and resident firmware. The interface board makes use of
a pair of gate arrays to implement the datalink frame checksum calculation and the
physical layer protocol.
The two gate array datalink/physical layer implementation will be described. One
gate array interfaces the ACR-NEMA EIA-485 transceivers to high speed buffer memory.
This gate array, the Datalink/Physical Layer Pipeline Processor (DLPP), is
responsible for the ACR-NEMA physical layer word transfer protocol as well as the
physical layer parity calculation. The DLPP also handles the datalink layer
checksum calculation in real time. The second gate array, the Datalink/Physical
Layer Controller (DLC), contains control and status registers for controlling and
monitoring the DLPP. The PLC is also responsible for managing the CR-NEM physical
layer interface arbitration.
Performance measurements for the Datalink/Physical Layer Pipeline Processor will be
detailed. AT/PASIF board level point to point communication performance
measurements will be described.
Comprehensive computerized medical imaging at Victoria General Hospital: final implementation plan
Paul Douglas Fisher,
Gerhard W. Brauer,
Josip Nosil,
et al.
Show abstract
A plan for the installation and implementation of a comprehensive computer-based system for the management and
communication of digital radiographic images and diagnostic information is described. The paper is based on the
authors' experience with, and evaluation of, prototype equipment and systems over the past 5 years. The final
configuration will be realized in 1992 at the completion of a 3-phase installation plan. The system will address the
clinical, data management, and administrative needs of the different types of users within the department, as well as
the requirement to distribute radiographic information and images to locations outside of the department. In order to
be considered successful, the system described herein will need to bring about a 90% reduction in both paper- and
film-based communication of images and information.
The British Columbia Ministry of Health is funding this phase of the project in order to obtain information on which
to base decisions regarding installation of similar systems at other sites within the Province and predict with some
confidence the cost effectiveness of such decisions.
Mayo/IBM PACS project: phase zero description
Dale G. Gehring,
James R. Salutz,
Everett G. Brooks,
et al.
Show abstract
A demonstration picture archiving and comniunication system (PACS) was
developed using standard networking protocols. The systera was developed
primarily to gain experience in digital image communications and optical
disk usage as well as to raeasure perforittance factors to be used in the
design of a substantially larger system.
The system consists of a General Electric SIGNA MRI system connected via
Ethernet to an IBM P5/2 Model 70, which serves as a gateway to a
token-ring network. Resident on the token-ring, along with the P5/2,
is an IBM AS/400 computer, an IBM System/36 with an optical storage
subsystem and an IBM PS/2-based image review work station.
Custom software was developed on each of the computers to control the
flow of data and to manage the storage and retrieval of images.
Standard TCP/IP software (File Transfer Protocol) is used to transfer
the images from the MRI system to the P5/2. The images are converted
into ACR/NEMA file format and made available to the communication and
archiving system. Under AS/400 control, P5/2 resident programs copy a
subset of the ACR/NEMA header information to an AS/400 database, and
copy all of the image files to the optical storage subsystem for
permanent storage. AS/400 programs were developed to enable database
query operations. User-selected images are transferred from the optical
storage subsystem either back to the MRI system or to the P5/2-based
image review work station.
Distributed approach for the development of integrated applications in PACS
Bernard Gibaud,
S. Rodriguez-Pereira,
A. Benslimane,
et al.
Show abstract
Recent PACS experiences have highlighted the critical aspects of PACS design. Three main topics are concerned: i) the
communication issues, ii) the management of data and iii) the system setting-up and evaluation methodologies; whereas the
first and the third aspects are widely presented in the literature, the second one is less discussed in papers although it may
have important repercussions on the whole system design. In this paper, we deeply analyse the problem of access to image
data from the functional, architectural and implementation viewpoints. The current trends investigated within the SIRENE
environment are presented: the proposed solution combines a centralized management of archives with basic indexing and
retrieval capabilities and a distributed management of applications on the workstations, offering a good flexibility for the
development of specific applications suitable in the various medical departments.
Analysis of discrepancies observed between digital and analog images during a clinical trial of IRIS
Morris Goldberg,
Marjorie Coristine,
Shawn Currie,
et al.
Show abstract
A clinical trial of an Integrated Radiological Information System (IRIS) was conducted
at the Ottawa Civic Hospital with the Department of Emergency Medicine and the Department of
Radiological Sciences between April 4, and May 12, 1989. During the trial, 319 active Emergency
Department cases (905 films) were processed using IRIS. Radiologists examined the digital
images on the image screen to formulate a diagnosis, then before dictating a report, they examined
the analog films. In 30 cases there was a discrepancy between the information obtained while
viewing the digital images on IRIS and the information obtained from the analog films. These
anomalous cases were used in an independent study of the discrepancies. In the study, each case
was reviewed in both digital and analog form by three physicians who provided a comparative
rating of diagnostic quality. Any perceived differences between the digital and analog media were
noted. Particular attention was paid to rating the relevance of the IRIS enhancement capabilities.
Although ratings for digital images were high, the comparative ratings for the film are in general
better. An analysis of the individual cases shows that: (i) most of the discrepancies probably
resulted from physician inexperience in reading radiographs in digital form, (ii) the IRIS
enhancement facilities significantly increase the ratings of satisfaction or perceived quality of digital
images and (iii) an appropriate choice of enhancement may make visible the required diagnostic
features for cases where some reviewers did not find the image/digital discrepant.
Database requirements for PACS
Show abstract
PACS offers new capabilities, but presents some new limitations as well. We reviewed radiology practice
at four medical centers. For interpretation of new images, most radiologists felt that the most recent
examination for comparison would suffice, except for chest radiographs, for which three prior exams were
frequently needed. All of the centers used alternators to review images, with from 5-14 separate reading
areas. PACS capabilities should include organization and delivery of cases for interpretation and
consultation to the appropriate area, pnoritization of cases, and rapid availability of inpatient and clinic
patient data.
Interfaces: Man and Machine
Voice recognition interface for a radiology information system
William H. Hinson,
Johannes M. Boehme,
Robert H. Choplin M.D.,
et al.
Show abstract
We have implemented a voice recognition interface using a Dragon Systems VoiceScribe-1000 Speech
Recognition system installed on an AT&T 6310 personal computer. The Dragon Systems DragonKey
software allows the user to emulate keyboard functions using the speech recognition system and replaces
the presently used bar code system. The software supports user voice training, grammar design and
compilation, as well as speech recognition.
We have successfully integrated this voice interface in the clinical report generation system for most
standard mammography studies. We have found that the voice system provides a simple, user-friendly
interface which is more widely accepted in a medical environment because of its similarities to tradition
dictation. Although the system requires some initial time for voice training, it avoids potential delays in
transcription and proofreading. This paper describes the design and implementation of this voice
recognition interface in our department.
Poster Session
User interface evaluation and X Windows
Paul L. Hofland,
Berend C. Stoel,
Fenno P. Ottes
Show abstract
BAZIS has set up an experimental imaging workstation with facilities for image input, storage, presentation and
manipulation. A software package called FRACTALS (Filmless Radiology And Computerized Task Analysis Lab
Software) has been developed for an IBM RT PC. An important feature of FRACTALS is a logging facility called
computerized task analysis. Every time FRACTALS is started, a journal file is created. This file contains information
on e.g. the images that has been displayed, options that has been invoked, window & level settings, time stamps. This
information can be used to evaluate the functionality of FRACTALS and to perform research on human behaviour
at radiology workstations.
In this paper we discuss the porting of FRACTALS from the RT PC to other systems, using the X Window
System. Furthermore we discuss the evaluation of the suitability of the RT PC input devices for a radiological
workstation using the results of event logging.
PACS workstation for computer-assisted image diagnosis
Minoru Hosoba,
Masato Horino,
Kunihiko Takemura,
et al.
Show abstract
Major two functions that a PACS workstation is considered to be equipped with are 1) efficient retrieval of
image data and 2) supporting or consultation of writing reports, as radiologists have to diagnose increasing
number of digital images in routine clinical studies. The authors developed a prototype PACS workstation
with high speed image retrieving architecture and computer aided diagnosis and reporting function by using
an artificial intelligence technology (AIPACS workstation). When physician selects the patient and his studies, the system performs feature extraction and generates diagnostic report by the inference engine with backward
reasoning using the knowledge installed as production rules. Clinical application to the system for thyroid
diagnosis showed good correlation with the diagnosis done by the physician.
Systems and Components
Trial of PACS employing magneto-optical disks
Kiyonari Inamura,
Tokuo Umeda,
Atsushi Takigawa,
et al.
Show abstract
Rewritable and compact media of magneto-optical disk (MOD) was firstly employed
by us to store medical images such as digital X-ray films. The purpose is to test
functions of communication media or circulating media as well as of filing media.
Another feature of our trial system is to involve voice recording module for
diagnostic reports. Method of clinical application and development approach of
our PACS with MOD is discribed in this paper. Technology assessment of our system
is also briefly descussed in terms of cost-effectiveness and security problem.
Poster Session
Environment for image processing development interfaced to PACS
Sumiyoshi Iwamori,
Makoto Aoki,
Minoru Satoh,
et al.
Show abstract
One of the reasons for the development of PACS is for use in medical image
CAD(Computer Aided Diagnosis). At present, there are few possibilities of
introducing image-processed CAD functions to PACS, because we have a number
of technical problems with the development of image-processed CAD. However,
most of these problems can be solved by improving the development environment
of image processing.
This paper explains the development environment of image-processed CAD
introduced to PACS. The software used to improve the emvironment consists of
three units; one is a device server, another is an image processing shell,
and still another is an image control window.
The major purpose of the improvement of the environment are to conceal
device dependent data from users, to reduce programming work by using a
hierarchical command system and to realize an easy-to-use environment
with user's friendly MIII.
Multimedia medical communication with ISDN technologies: early experiences
Peter F. Jensch,
Heino Niemann
Show abstract
ISDN provides the end user with a large number of services and the flexibility to easily modify the services they
receive as their communications needs grow and change. It is our goal to use the advantages of the ISDNtechnology
for a medical end user by supporting him with integrated image/voice/data information. We focus our
developments to medical scenarios where general PACS concepts are not acceptable, currently or in the near
future.
An image/voice/data management and communications system using ISDN technology has been designed. First
applications are developed
- to acquire multiple image modalities such as CT, Angio and NI from several hospital departments,
- to communicate with a remote image processing group (Computer Science Department),
- to complement visual results wIth voice and data yielding integrated multimedia information, and
- to distribute integrated multimedia information to medical end users such as surgeons and therapists.
The integrated multimedia information is finally available at a specially configured PC-workstation in complete
digital form. An interactive replay of this information complies with a video-standard (either NTSC or PAL) and may
discard specific media-modality on demand. At any time a video copy of the complete or constituent integrated
information can be saved on VHS-cassettes for further distribution.
The image processing group currently creates standardized video clips for frequent surgical scenarios.
This paper describes the network model for the in-house and remote ISDN communication of integrated
multimedia information, traffic, and performance requirements. The flexibility and acceptance of this approach will
be addressed by reviewing several surgical cases.
Image format overcomes hardware vendor barriers
Show abstract
The Rockwell Digital Imagery Standard (RDIS) format for images was developed in
response to the need for an independent image format device. The Rockwell Digital
Image Standard format has been designed to be device independent. The RDIS format
releases technical staff from hardware limitations and allows the use of whatever
image display system is available to them.
Agreement experiments: a method for quantitatively testing new medical image display approaches
Richard Eugene Johnston,
Bonnie C. Yankaskas,
John R. Perry,
et al.
Show abstract
New medical image display devices or processes are commonly
evaluated by anecdotal reports or subjective evaluations which are
informative and relatively easy to acquire but do not provide quantitative nieasures. On the other hand, experinients eniploying ROC analysis, yield quantitative measurements but are very laborious and
demand pathological proof of outcome. We have designed and are employing a new approach, which we have termed "agreement experiments," to
quantitatively test the equivalence of observer performance on two
systems. This was specifically developed to test whether a radiologist
using a new display technique, which has some clear advantages over the standard technique, will detect and interpret diagnostic
signs as he would with the standard display technique.
Agreement experiments use checklists and confidence ratings to
measure how well two radiologists agree on the presence of diagnostic
signs when both view images on the standard display. This yields a
baseline measure of agreement. Agreement measurements are then
obtained when the two radiologists view cases using the new display,
or display method, compared to the standard technique. If the
levels of agreement when one reads from the new and one reads from
the standard display are not statistically different from the
baseline measures of agreement, we conclude the two systems are
equivalent in conveying diagnostic signs.
We will report on an experiment using this test. The experiment
compares the agreement of radiological findings for chest CT
studies viewed on the conventional multiformat film/lightbox to
agreement of radiological findings from chest CT images presented on a
multiple screen video system. The study consists of 80 chest CT studies. The results were an 86% to 81% agreement between the two viewing
modalities which fell within our criteria of showing agreement.
Multimedia database design and architecture in radiology communications
Ahmed Karmouch,
Nicolas D. Georganas,
Morris Goldberg
Show abstract
Multimedia database is a fundamental component in the Multimedia Radiology Information System. It
provides mean by which different classes of documents (diagnostic reports, images, patient
information, etc), involving several media (text, image, graphics, voice), are structured, represented,
stored, manipulated and retrieved. In this paper, we first present the requirements for a multimedia
database along with the data model used to describe the radiology information and procedures. Then,
we describe our approach to the multimedia database design and architecture, and the corresponding
prototype instance in terms of implementation and storage strategies. Finally, we give a conclusion
with an overview of the research undertaken for enhanced multimedia data management
Algorithms for the reduction of CT artifacts caused by metallic implants
Ernst Klotz,
Willi A. Kalender,
Roman Sokiransky,
et al.
Show abstract
The paper presents an analysis of the different metal artefact generating
effects in X-ray CT and discus3es several algorithmic approaches to reduce their
influence. They all share a segmentation step in which the artefact-causing
implants are automatically located in the more or less degraded original
backprojected image and the subset of affected measurement data is identified.
The original image is reconstructed from appropriately scaled ray data that
permit a truthful display of implants and the proper assessment of their
geometry. Algorithms discussed are simple data substitution by interpolation,
data substitution by interpolation enhanced by reprojected high-contrast
information and data correction by modelling of artefcat generating physical
phenomena.
Dutch PACS project: results of phase one (1986-1989)
Jef M.L. Kouwenberg,
Fenno P. Ottes,
Albert Reinder Bakker,
et al.
Show abstract
During the period 1986-1989, the first phase of a research project in the field of computer systems for storage,
communication and display of radiological images, has been carried out. This project has been financially supported
by the Dutch Ministery of Health Care (WVC). Such systems are internationallyreferred to with the acronym PACS
(Picture Archiving and Communication Systems).
The project was jointly performed by three partners:
- The Utrecht University Hospital (UUH)
- BAZIS, Central Development and Support Group HIS, Leiden
- Philips Netherlands/Philips InternationalB.V., product division Medical Systems.
This paper will give an overview of the experiences and results which evolved from the first phase of this research
project. The conclusion is that the PACS concept is attractive, but that further research will be necessary to make it
implementable on full-scale. Recommendations for the continuationof PACS research in the Netherlands are made.
Integrating a radiology information system with a picture archiving and communications system
Show abstract
Images stored in the central database of a picture archiving and communications system (PACS) must be identified
and described with textual information such as patient name, exam procedures, and diagnostic reports. Most
radiology departments already use a radiology information system (RIS) for departmental administrative functions,
such as exam scheduling, film tracking, billing etc., so this information is readily available. Ideally, the PACS and
the RIS should be combined into one complete system, which is not easily achievable due to costly investment of
replacing the current RIS and slow clinical acceptance of the PACS. Alternatively, for a successful PACS operation
using the existing RIS, the two systems should be linked together so that the PACS can freely retrieve the RIS
information whenever the need arises.
As a part of the PACS evaluation project, an interface system to link our RIS (DECrad) to our PACS (AT&T
CommView) has been implemented using an external microcomputer system running UNIX. The interface system
handles proprietary communication protocols on each side, translating the information from one format to the
other. Although the interface system translated the RIS transactions and transferred them to the PACS, they
were not always associated with the image data at the PACS. This paper presents the design concept and the
implementation details of the interface system we have developed. The performance and the problem areas of the
interface system are also investigated, as well as suggesting future directions for a better implementation.
Analysis of data assembling activities for radiologists and its implications for clinical acceptance of PACS
Show abstract
This paper discusses the tasks that a Intelligent Diagnostic
Radiology Workstation (IDRW) should be able to perform in
addition to serving as an image review station. Included in our
discussion are the types of data that an IDRW must handle. It is
hoped that this discussion will lead to improved, friendlier, and
more intelligent workstations which will be accepted by
radiologists.
HIS-PACS coupling in perspective
Herman Lodder,
Bas M. van Poppel,
J. B.M. Wilmink,
et al.
Show abstract
Within the framework of the Dutch PACS project (a cooperation in the PACS field of BAZIS, the Utrecht
University Hospital and Philips Medical Systems) a coupling between a HIS and a prototype PACS was realized and
evaluated during clinical practice. This one-way coupling is a first step towards a so-called Image Information System,
which can be seen as (logically) one system instead of two (a HIS for storage and retrieval of administrative and
medical data, and a PACS for the images). The BAZIS/HIS is an integrated HIS, containing about 70 subsystems
including a RIS, which is now used in about 40 hospitals in the Netherlands. The main reasons for
coupling/integrating a HIS and a PACS can be summerized as: a) the user need for both functional and information
integration and b) the need to have access to HIS data for optimizing image database and network management in
order to get acceptable response times.
As follow-up to the paper presented in the 1989 conference this paper will focus on the experiences gained with
this one-way coupling. The event-driven communication took place by sending messages from HIS to PACS in ACRNEMA
format. From these experiences recommendations for a next phase: a two-way link between a HIS and a
PACS will be given. The necessity for bidirectional datatransfer will be discussed. Directions for future research e.g.
on prefetching strategies will be pointed out.
Voice recording module for PACS
Mansur Loloyan,
Ricky K. Taira,
Alek S. Hayrapetian,
et al.
Show abstract
This paper describes the integration of a voice recording module in our existing PACS system at the UCLA
Department of Radiology. This module consists of a personnal computer, speech signal digitizer, and a hard disk with
appropriate amount of memory storage to handle a given number of reports. The system has the ability to record and store
spoken reports in digitized form and play back an existing dictated report. Moreover, the voice module can be activated
locally from its own keyboard or by receiving appropriate commands from two remote mini-computers which are used as
review and diagnostic display workstations respectively.
Evaluation and critique of the ACR-NEMA standard for picture archiving and communications systems
Show abstract
The ACR-NEMA standard for communications in digital radiology has been a topic for much discussion
lately. The standard was developed to facilitate the development of multivender products which
can communicate using a point-to-point standard interface. In this paper we describe, the combined
experiences of Toshiba, Radiology, and Electrical and Computer Engineering at the University of Anzona
with the ACR-NEMA standard. We also offer a candid evaluation and critique of the standard, for
consideration by implementors of the current standard.
The paper summarizes a prototype development effort using a high speed fiber optic network and the
ACR-NEMA standard interface. We discuss the overall architecture of the prototype and the software
design based on the International Standard Organization (ISO) upper layers. The transport layer and
below was implemented using a Matrix-developed ACR-NEMA interface board. The paper discusses the
problems encountered in the application of the ACR-NEMA standard in a networking environment for
Picture Archiving and Communications Systems (PACS). We conclude that the current form of the ACR-
NEMA standard does not provide a workable foundation for the development of cost effective and efficient
digital radiology interfaces, especially in a networked PACS. We also discuss the PACS environment
beyond the current ACR-NEMA standard and make recommendations for the feature direction of the
standard.
Prototype of image compression system for medical images
Yukihiro Nakagawa,
Toshiyuki Yoshitake,
Yoshiyuki Ohta,
et al.
Show abstract
We previously developed an image reconstruction display for reconstructing images compressed by our hybrid
compression algorithm. The hybrid algorithm, which improves image quality, applies Discrete Cosine Transform
coding (DCT) and Block Truncation Coding (BTC) adaptively to an image, according to its local properties. This
reconstruction display receives the compressed data from the host computer through a BMC channel and quickly
reconstructs good quality images using a pipeline-based microprocessor.
This paper describes a prototype of a system for compression and reconstruction of medical images. It also
describes the architecture of the image compression processor, one of the components of the system. This system
consists of the image compression processor, a host main-frame computer and reconstruction displays. Under this
system, distributed processing in the image compression processor and the image reconstruction displays reduces
the load on the host computer, and supplies an environment where the control routines for PACS and the hospital
information system (HIS) can co-operate. The compression processor consists of a maximum of four parallel
compression units with communication ports. In this architecture, the hybrid algorithm, which includes serial
operations, can be processed at high speed by communicating the internal data. In experiments, the compression
system proved effective: the compression processor compressed a 1k x 1k image in about 2 seconds using four
compression units. The three reconstruction displays showed the image at almost the same time. Display took less
than 7 seconds for the compressed image, compared with 28 seconds for the original image.
Queueing models of picture archiving and communication systems
Hassan Khanmoradi,
Arne A. Nilsson
Show abstract
At present the management of radiological information is done manually in most hospitals. Images from the
digital modalities (e.g. Computer- tomography scanners, X-ray machines) are converted into films and
stored in a room. These films are then distributed manually and interpretation is done by reading the films
through light boxes. With the advances in semiconductor technology and digital processing techniques it is
now possible to automate these operations by using a digital system for archiving and communication of
images. A Picture Archiving and Communication System (PACS), is a digital system for acquiring,
storing, moving and displaying picture or image information .These systems are highly dependent on the
new technology for mass storage of data on optical disks. In the medical environment, the ultimate goal of
using digital images and PACS is tohave a radiology department without filmjackets 2,3 A typical PACS
consists of a database of medical images, display stations, acquisition systems and the communications
medium. There are two possible architectures for PACS, one is the distributed PACS where all the
modules are linked together through a high speed communication medium, and the other is a centralized
PACS where the acquisition nodes and the display stations are part of the system which comprises the
image database 4. In this paper we present analytical queueing models of distributed PACS used in the
medical environments. These models are for the image database, the picture viewing stations, and the
communication channels.
Hospital-integrated PACS: R&D effort of the European communities
Fenno P. Ottes,
Albert Reinder Bakker,
Rudy A. Mattheus,
et al.
Show abstract
A PACS research project under the name " FOUNDATIONS FOR A HOSPITAL INThGRATED PICTURE
ARCHIVING AND COMMUNICATION SYSTEM" is currently conducted. The overall objective is the modular
conception of an experimental knowledge-based medical information management and distribution system.
Image/text document access and display will be based on an intelligent user interface for diagnostic image
workstations. The concept will comprise the integration of PA.S with the functions of the Hospital Information
System. It will be based upon standards and be realized by an interactive collaborationbetween 7 european research
groups from universities, hospitals and industries. The multi-disciplinary groups will consist of engineers, computer
scientists, medical doctors (both radiologists and clinicians) and physicists.
The HIPACS project has a budget of ECU 1.3 million, of which 50% is provided by the Commission of European
Communities (CEC) within the scope of the exploratory phase of the Advanced Informatics in Medicine (AIM)
research programme. HIPACS is directed by Prof. M. Osteaux, the prime contractor.
This paper first explains the backgrounds of the AIM program. Next, the objectives of the HIPACS project are
reviewed. The cooperating partners and their (scheduled) research activities are listed. Finally, the continuation of
HIPACS within scope of the main phase of AIM is discussed.
Performance characteristics and model for the Mayo/IBM PACS project
Kenneth R. Persons,
Allen B. Benson,
Mark J. Pavicic,
et al.
Show abstract
This paper discusses the performance aspects ofthe joint Mayo/IBM PACS project. It includes performance
measurements made during Phase Zero, and the early stages of Phase One. It also considers the
network traffic load distribution and bandwidth utilization for the final Phase One topology. Based on
earlier performance measurements and projected load distributions, performance projections are
made for the completed Phase One PACS network. Finally, the paper discusses the approach being
taken by the department of Computer Science at North Dakota State University to develop a useful
model of this PACS network.
Cost analysis model of digital imaging networks: results of a comprehensive sensitivity analysis
Gabriel S. Plumlee,
Harold R. Benson,
Bruce Majors,
et al.
Show abstract
The Cost Analysis Model for Digital Imaging Networks (CAMDIN) is a life cycle cost
analysis model of the financial impact of PACS technology upon the radiology department at
Georgetown University Hospital. The model (which uses the Javelin Plus economic modeling
package with data from Georgetown University Hospital and AT&T's CommView system)
follows the costs and revenues within radiology both with and without the PACS network.
CAMDIN guides the user in building a model tailored to an individual radiology department. It
allows for sensitivity studies and produces practical results in several levels of detail clearly and
quickly. Sensitivity studies have been performed on this system to determine the relative weights
of several factors of PACS implementation.
Teaching-file-based workstation for radiology
Show abstract
The aim of the teaching workstation project is to develop a radiology workstation useful to students, practitioners,
researchers, and faculty as a radiology learning and research tool. The user will develop skills and experience in
interpretation through the teaching file cases as well as an understanding of the usage and capabilities of the host
PACS system. This document represents the specifications and design for an effective teaching workstation built
upon the Advanced Physicians Workbench, also under development at Georgetown University Hospital.
Efficient compression of medical images through arithmetic coding
Tenkasi V. Ramabadran,
Keshi Chen
Show abstract
A new method for the noiseless compression of medical images is described. The method uses the wellknown
DPCM technique (i.e. , linear prediction) for decorrelating a given image. However, instead of
encoding the pixels of the decorrelated image using a memoryless model as in the conventional method, a
source model with several conditioning events (or contexts) is employed. The contexts are based on the
horizontal and vertical components of the gradient in the given image as well as the predicted value of a
pixel. The statistics under each context of the model are obtained adaptively. In order to encode the
decorrelated image as an outcome of such a complex source model, the powerful arithmetic coding
technique is employed. Experimental results show that the new method can compress typical medical
images 20% to 30% better than the conventional method.
Implementation Experiences of the Commview System Pacs Applications
Initial experience with automatic image transmission to an intensive care unit using PACS technology
Carl E. Ravin
Show abstract
This report describes the refinement of the interaction between a CR system and PACS that has
made the automatic distribution of images to specified locations possible. Those interactions between
the CR and the PACS that were considered important to the acceptance of the data to be sent to the ICU
are described. Display and user interface considerations that were important for physician acceptance
of the unit are also discussed.
System enhancements and future applications will be developed based on the possible implications
of this technology in both Radiology and the ICUs.
Poster Session
Display conditions and lesion detectability: effect of background light
Mahmood Razavi M.D.,
Theodore R. Hall M.D.,
Denise R. Aberle,
et al.
Show abstract
We assessed the effect of high background light on observer performance for the detection
of a variety of chest radiographic abnormalities. Five observers reviewed 66 digital hard
copy chest images formatted to 1 1 x 14 inch size under two display conditions: 1) on a
specially prepared 1 1 x 14 inch illuminated panel with no peripheral light and 2) on a
standard viewing panel designed for 14 x 17 inch radiographs. The images contained one
- or more of the following conditions: pneumothorax, interstitial disease, nodules, alveolar
process, or no abnormality. The results of receiver operator characteristic analysis show
that extraneous light does reduce observer performance and the detectability of nodules,
interstitial disease.
High-speed ACR/NEMA interface
Gerard L. Reijns,
D. Santilli,
G. Schellingerhout,
et al.
Show abstract
The design and implementation of a standard high speed ACR-NEMA communications interface is described.
The upper layers e.g. the Presentation layer, Session layer and part of the Transport/Network layer have been
implemented in software. In order to reach the speed requirement of 8M byte/sec. the lower layers e.g. part of the
Transport/Network layer and Data Link layer have been implemented in hardware. We have developed and built
an interface for an IBM personal computer P5/2 model 50, working under the operating system OS/2. The PS/2,
model 50 has been equipped with a fast micro-channel bus, which enables a large throughput. The operating systern
OS/2 has a multitasking capability, which enables concurrent programming. In order to minimize the delays,
we used this multitasking facility to create a number of parallel operating "threads". The Transport/Network layer
functions have been implemented using a receive thread, two send threads and a device driver with three hardware
registers. The time to transfer a packet by DMA, to initiate the DMA logic and to execute the required Kernal
functions have each been measured and figures are shown. The Data Link layer provides for storage of two
packets in two separate random access memories (RAM's). These two RAM's enable a pipelined operation, which
minimizes the delay in the Data Link layer.
Requirements for a documentation of the image manipulation processes within PACS
Klaus Retter,
Otto Rienhoff,
Ch. Karsten,
et al.
Show abstract
This paper discusses to which extent manipulation functions which
have been applied to images handled in PACS should be documented.
After postulating an increasing amount of postprocessing features on
PACS-consoles, legal, educational and medical reasons for a
documentation of image manipulation processes are presented.
Besides legal necessities, aspects of storage capacity, response
time, and potential uses determine the extent of this documentation.
Is there a specific kind of manipulation functions which has to be
documented generally? Should the physician decide which parts of the
various pathways he tries are recorded by the system? To
distinguish, for example, between reversible and irreversible
functions or between interactive and non-interactive functions is
one step towards a solution. Another step is to establish
definitions for terms like "raw" and "final" image. The paper
systematizes these questions and offers strategic help. The answers
will have an important impact on PACS design and functionality.
PACS economics and the referring physician
Allan O. Saarinen,
M. C. Wilson,
Scott C. Iverson,
et al.
Show abstract
One of the touted potential benefits of Picture Archive and Communications Systems
(PACS) is that these systems will save referring physicians significant time by eliminating
their trips to andfrom the radiology departmentfile room. To date, this potential savings
has not been quantified in any hospital setting. Economic modeling of PACS by the
University of Washington demonstrates that the cost savings of PACS is extremely
sensitive to small productivity changes in referring physician time savings. To provide
analytical strength to this argument and supportfor the overall importance of the referring
physician in PACS economics, trip distribution data was collected at the University to
determine the average time referring physicians spend traveling to andfrom the radiology
departmentfile room. This travel time is significant and it corroborates other work by the
authors suggesting the benefits of PACS may be, in fact, larger outside the radiology
department than inside it.
Information for this study was obtained from two sources. In one case, referring
physicians were queried about the time they and their support staffspend requesting and
retrievingfilmfilesfrom thefile room by using a comprehensive hospital-wide survey. In
the second case, the distance between all major clinics in the University medical center and
the number offilm files each clinic checks out weekly were entered into a conventional
transportation trip distribution model toforecast the time staffspend on this activity. While
some differences in the results occurredfrom the two cases, each case generally showed a
significant expenditure of effort approaching approximately two-weeks per year per
referring physician with a potential recovery value of between $3 to $8 million dollars
annually in additional billable revenue, assuming adequate patient demand.
Clinical determinants of PACS acceptance
Show abstract
One of the key determinants influencing how successfully a radiology department can
convert from a conventional film-based environment to an exclusively digital imaging
environment may be how well referring physician members of the hospital staff who are
not radiologists endorse this new system. The benefits of Picture Archive and
Communication Systems (PACS) to radiologists are becoming widely accepted and
documented; however, physicians who interact with the radiology department represent an
important user group whose views on PACS are less well understood. The acceptance of
PACS by referring physicians (clinicians) may be critical to the overall utility ofPACS as
well as a major drivingforce behind why a hospitalpurchases PACS. The degree to which
referring physicians support PACS may be dependent upon many factors.
This study identifies several aspects through the administration and analysis ofa survey
which improve PACS acceptance by nonradiology physicians. It appears the more patients
a referring physician sends to the radiology department, the more time a physician spends
traveling to andfrom thefllmflle room retrievingfllms, and, the more interested a referring
physician is about computers, the higher his interest is in PACS. If a referring physician
believes that PACS will save him or her time, will reduce the incidence oflostfilms, or will
cause performance of radiology exams or generation of reports to be more efficient, the
referring physician appears more likely to support PACS and to make the initial time
investment necessary to learn how PACS equipment operates.
The factors which cause referring physicians to support PACS are principally: (1) the
elimination oflost, misplaced, and checked outfllms, and (2) the elimination oftrips to and
from thefile room. The major distractions ofthe technology are: (1) system reliability, and
(2) reduced diagnostic capability. While the high cost ofPACS is also a distraction, it is
not the predominant concern.
Potential time savings to radiology department personnel in a PACS-based environment
Allan O. Saarinen,
M. C. Wilson,
Scott C. Iverson,
et al.
Show abstract
A purported benefit of digital imaging and archiving of radiographic procedures is the
presumption of time savings to radiologists, radiology technologists, and radiology
departmentpersonnel involved with processingfilms and managing theflimfile room.
As part of the University of Washington's evaluation of Picture Archiving and
Communication Systems (PACS)for the U.S. Army Medical Research and Development
Command, a study was performed which evaluated the current operationalpractices of the
film-based radiology department at the University of Washington Medical Center
(UWMC). Industrial engineering time and motion studies were conducted to document the
length of time requiredforfilm processing in various modalities, the proportion of the total
exam time usedforfilm processing, the amount of time radiologists spent searchingfor and
looking at images, and the amount of time file room personnel spent collating reports,
making loans, updatingfilm jacket information, and purging files.
This evaluation showed that better than one-half of the tasks in the file room may be
eliminated with PACS and radiologists may save easily 10 percent of the time they spend
reading films by no longer having to searchforfilms. Radiology technologists may also
save as much as 10 percent of their time with PACS, although this estimate is subject to
significant patient mix aberrations and measurement error. Given that the UWMC
radiology department operates efficiently, similar improvements are forecast for other
radiology departments and larger improvements areforecastfor less efficient departments.
IRES: image retrieval expert system
Olivia R. Liu Sheng,
Hui-Chin Wang,
Hong-Mei Chen Garcia
Show abstract
Image Retrieval Expert System (IRES), a knowledge-based system for automatic image retrieval, is being
prototyped at the University of Arizona (U of A). IRES is to couple with the distributed database system
designed for Structured PACS (S-PACS)1 to achieve the high system performance required by radiologists.
IRES encompasses the "intelligence" of multiple expert radiologists. The system will predict and migrate
the "old" images needed for comparison purposes during radiological exam readings from slower or remote
storage devices to the local buffers of workstations. The use of IRES with the PACS Distributed Database
System (DDBS) is expected to shorten the PACS system response time, save the time of radiologists in
selecting films, minimize the turnaround time of the exam interpretation function, and increase diagnostic
effectiveness by providing relevant images automatically. This paper presents the implementation details
of this IRES prototype.
Image Filling and Retrieval Schemes
Distributed database design and modeling for PACS
Olivia R. Liu Sheng,
Hong-Mei Chen Garcia,
Chih-Ping Wei,
et al.
Show abstract
The delivery of an operable Picture Archiving and Communication System (PACS) that will meet a
hospital's high performance requirements is hampered by severe bottlenecks encountered in the database
(DB) and communication systems of a centralized architecture. As an alternative to a centralized design,
a distributed DB design that physically allocates and potentially replicates data across a hospital has
been modeled and evaluated for PACS at the University of Arizona. Because of geographic dispersion of
image generation and "local interest" in image retrieval, a distributed DB design approach has a liatural
appeal to PACS. This paper examines the issues of a distributed PACS DB design, describes our modeling
approach, and presents the results of a preliminary performance evaluation of two distributed DB designs
vs. a centralized design for PACS The results of our simulation experiments show that there is a significant
improvement of response time in a distributed architecture due to the effects of "local reference" and "load
balancing."
Poster Session
Requirement analysis for PACS database system
Show abstract
The sound design of any system begins with a full understanding of user requirements and the environment
in which the system is to operate. The process of obtaining this understanding is called requirement
analysis. The design of a Picture Archiving and Communication System (PACS) Database (DB) also
starts with a requirement analysis, following a systematic top-down DB design approach. The purpose of
a DB requirement analysis is to provide the information necessary for deriving DB design specifications.
This paper presents the results and implications of a year long intensive requirement analysis for a PACS
DB at the University Medical Center (UMC) of the University of Arizona (U of A).
First experiences with a semantic modeling method to guide simulation-based PACS development
W. J. J. Stut Jr.,
M. R. van Steen,
L. P.J. Groenewegen,
et al.
Show abstract
The design of PAC systems benefits from modelling and simulation. Within the scope of the Dutch PACS project
several simulation studies have shown that simulation is a powerful tool to evaluate hardware architectures, image
management strategies and clinical working methods before they are actually implemented. Besides using simulation
techniques for obtaining insight into a PACS's performance and behaviour, they can also be applied to actively
support the design of a PACS. In order to capture the full complexity of PAC systems in a simulation model, and to
take full advantage of simulation as a design tool, we are currently developing new techniques for model
construction. This paper summarizes the underlying principles of our modelling method, and describes our first
experiences with it.
Integration of clinical routine digital imaging and advanced image processing through PACS
Bart M. ter Haar Romeny,
Max A. Viergever,
P. F. G. M. van Waes,
et al.
Show abstract
The University Hospital Utrecht (UHU) has been the site for clinical evaluation of a prototype
Picture Archiving and Communication System (PACS), as a part of the Dutch PACS project run
by BAZIS, Phffips Medical Systems and the UHU in the period 19864989 k
The 800 bed UHU moved in July 1989 to a new campus site facifity (Figure 1.). This offered
the opportunity to design the new radiology department to be prepared for a future large scale
PACS. The set-up includes an ergonomically designed digital reading room, a centrally located
computer room, cooling and cabling, a video network covering the total department and
facilities for teleradiology. Radiology, Radiotherapy and Nuclear Medicine are organized in one
department.
UW PACS prototype performance measurements, computer model, and simulation
R. K. Panwar,
C. S. Wang,
Larry A. DeSoto,
et al.
Show abstract
A PACS prototype has been installed and evaluated at the University of Washington. This paper presents the
work done in the performance evaluation of the PACS prototype. The work involved network and workstation
performance measurements and development of a simulation model based on the performance measurements. The
simulation model was then used to do a parametric study of the PACS prototype to pinpoint the bottlenecks and
suggest corrective measures. Results show that there are some local bottlenecks in the PACS prototype and an
overall global bottleneck in the Data Management System (DM5) which forms the hub of the PACS prototype.
Investment alternative: the status quo or PACS?
John A. Vanden Brink,
Jozef K. Cywinski
Show abstract
While the cost of Picture Archiving and Communication Systems (PACS) can be substantial, the cost of
continuing with present manual methods may become prohibitive in growing departments as the need for
additional space and personnel (both technical and professional) to meet the increasing requirements for all
image management activities continues to grow. This will occur simultaneously with increasing pressures on
problems of the present system, i.e., lost films, lost revenues, delayed reporting and longer diagnostic cycle times.
Present methods of image archiving communication and management i.e. the relationship of procedure volume
to VFE requirements for professional and technical personnel, costs of film, film storage space, and other
performance factors are analyzed based on the database created by the Technology Marketing Group (TMG)
computerized cost analysis model applied to over 50 US hospitals. Also, the model is used to provide the
projected cost of present methods of film management for an average US 400 +bed hospital based on ten year
growth rate assumptions. TMG PACS Tracking data provides confirmation of staffmg pattern correlation to
procedure volume. The data presented in the paper provides a basis for comparing the investment in maintaining
the status quo to an investment in PACS.
Prototype medical workstation for computer-assisted stereotactic neurosurgery
Show abstract
We present a prototype system for computer assisted stereotactic neurosurgery. It is especially suited to integrate
vascular data with the stereotactic trajectory and with other information obtained from different imaging modalities.
Patient image data from CT, MRI and DSA are acquired using a patient-fixed stereotactic frame with additional
external markers for image registration. After preprocessing, all data are available for stereotactic planning and
confirmation of electrode positioning. Interactive 3D devices simulate the electrode trajectory, which is projected on
a stereoscopic set of angiograms. Alternatively, cross-sections of this trajectory with each of the CT or MR slices
can be calculated at the same time. Additional features such as reslicing of the original CT or MR slices along the
probe trajectory, are being implemented.
All software is written on a 3D graphics workstation. In addition, we use a stereoscopic imaging system employing
electro-optical shuttering glasses, and a 3D cursor in stylus form for the simulation of the electrode trajectory.
Why do cost-benefit studies of PACS disagree?
Elisabeth M.S.J. van Gennip,
Fenno P. Ottes,
Bas M. van Poppel,
et al.
Show abstract
Once the technical difficulties of PACS have been solved, the main obstacle for its introductionwill be its costs. Even
though PACS is still under development, it is clear that the equipment for PACS will be much more expensive than
the equipment used in the conventional situation. PACS may, however, pay itself back by allowing savings of film,
space and personnel.
The conclusions of some recent cost-benefit studies disagree on the costs and benefits of PACS. Some conclude that
PACS would pay for itself, whereas according to others PACS would be (much) more expensive.
We analyzed the latest cost-benefit studies, to find out why their outcomes diverge.
The comparison of the results revealed striking differences. The calculations of the annual costs of a hospital wide
PACS varied between 2 and 4 million dollars. These differences could not be explained by differences in the size of
the hospitals, as indicated by the number of examinations. They were, in part, caused by the fact that the costs per
piece of equipment, material or space varied per study. For instance the costs of 1 square foot of (archive) space
varied from $10 to $140 per year. The variation in the given costs of the film based system, depended on the fact
whether the time spent by medical personnel on film management was taken into account.
The differences among these studies demonstrate clearly the need for uniform, well-defined criteria for the
calculation of the costs and savings of PACS.
First results with the software package CAPACITY for cost modeling of PACS
Bas M. van Poppel,
Elisabeth M.S.J. van Gennip,
Albert Reinder Bakker,
et al.
Show abstract
An essential element in the decision of introducing a PACS will be its financial implication. We all hope PACS
will come affordable at a certain point in time because of the decreasing hardware prices. However there is a wide
variety of opinions about the moment the savings of PACS will exceed its costs.
A software package for cost modelling of PACS, named CAPACITY, was developed by BAZIS in order to to get
a better understanding of the cost characteristics of PACS. CAPACITY makes a cost comparison over the years thus
indicating the moment of break even. User given input values are checked by a critique module and a file of cases
can be maintained.
One of the activities within the Dutch PACS project, a cooperative effort of BAZIS, the Utrecht University
Hospital (UUH) and Philips Medical Systems is to indicate the costs of a PACS in the Utrecht University Hospital.
A number of scenarios for a PACS in the Utrecht University Hospital have been defined and evaluated with the
software package CAPACITY. The results will be discussed and it will be shown that the workstations play a major
role.
Comprehensive computerized medical imaging: interim hypothetical economic evaluation
Rebecca N. Warburton,
Paul Douglas Fisher,
Josip Nosil
Show abstract
The 422-bed Victoria General Hospital (VGH) and Siemens Electric Limited have since 1983 been piloting the implementation
of comprehensive computerized medical imaging, including digital acquisition of diagnostic images,
in British Columbia. Although full PACS is not yet in place at VGH, experience to date habeen used to project
annual cost figures (including capital replacement) for a fully-computerized department. The resulting economic
evaluation has been labelled hypothetical to emphasize that some key cost components were estimated rather
than observed; this paper presents updated cost figures based on recent revisions to proposed departmental equipment
configuration which raised the cost of conventional imaging equipment by $0.3 million* and lowered the cost
of computerized imaging equipment by $0.8 million.
Compared with conventional diagnostic imaging, computerized imaging appears to raise overall annual costs at
VGH by nearly $0.7 million, or 11.6%; this is more favourable than the previous results, which indicated extra
annual costs of $1 million (16.9%). Sensitivity analysis still indicates that all reasonable changes in the
underlying assumptions result in higher costs for computerized imaging than for conventional imaging.
Computerized imaging offers lower radiation exposure to patients, shorter waiting times, and other potential
advantages, but as yet the price of obtaining these benefits remains substantial.
PACS in the Utrecht University Hospital: final conclusions of the clinical evaluation
J. B.M. Wilmink,
Bart M. ter Haar Romeny,
Frits Hendrik Barneveld Binkhuysen,
et al.
Show abstract
In the past three years, a clinical evaluation of a PACS has been performed in the Utrecht University
Hospital as part of the Dutch PACS project. The clinical evaluation focussed on the following aspects:
technical evaluation of the prototype PACS equipment coupled to the HIS; diagnostic accuracy studies;
studies concerning the impact on the organization of the radiology-department and the referring wards;
and cost-savings analysis.
Some of the results of these subprojects have already been presented at previous SPIE conferences. In
this paper the general condusions are presented about the usefulness of the evaluated PAC-System in the
daily routine of radiology department and clinic. By making available the images of radiological
examinations fast, complete, reliable and continously on the ward, concrete improvements with regard to
the current process could be realized. The possibilities of PACS caused an increasing enthousiasm among
the clinicians. By the easier access to all images of their patients during 24 hours/day, they saw more
images on the day of the examination and images could be more easily used at consultations of other
specialists.
The overall conclusion is positive, but a lot of work has to be done to transform PACS from an
experimental setup into a routine production system on which a flimless hospital can be based. A complete
PACS needs an inteffigent Image Management System, which indudes prefetching algorithms based on data
from the Hospital Information System and automated procedures for removing obsolete images from the
local buffers in the workstations.
As yet PACS is very expensive, and the direct savings in the hospital cannot compensate for the high
costs of investment. Possibly PACS can contribute to a shorter stay of patients in the hospital. This will
lead to savings for government and health insurance companies and they can be expected to contribute to
PAS implementation studies.
Architecture of an optical jukebox image archive
Sridhar B. Seshadri,
Ronald L. Arenson,
Douglas F. Sprague
Show abstract
The Radiology Department at the Hospital of the University of Pennsylvania
is currently expanding its prototype Picture Archiving and Communications
System ( PACS ) into a fully functional clinical system. The fi rst phase of
this expansion involves three major efforts: the upgrade of the 10-Mbit
token-ring to an 80-Mbit backbone with associated subnets, the
implementation of a large-scale image archive, and, an interface between
the PACS and the Department's Radiology Information System. Upon completion
of this phase, the PACS will serve the storage and display needs of four
MRI scanners and four of the Hospital' s Intensive Care Units . To achieve
these objectives the Department entered into a joint development agreement
with Vortech Data Inc. to develop applications-software for an optical
jukebox-based image archive. This paper describes the developmental effort
with special reference to the Image Archival and Retrieval System ( IRS).
The IARS has three major features: a robust ACR/NEMA style protocol for
external communication, a hierarchical storage system that incorporates
magnetic, optical and shelf storage systems, and, a storage capacity that
can be incrementally expanded from 25 GigaBytes to 7 TeraBytes.
Image degradation in PACS
Show abstract
For PACS to be clinically desirable, transmiued imagery must be optimized for the various clinical and
research tasks. There are several processes that potentially degrade the diagnostic utility of the iransmitted
imagery. We examined our CommView PACS system at San Francisco VA Medical Center (SFVAMC)
to determine if imagery was altered from the original during passage into and through PACS, and whether
the alteration had any discernable effect on current or projected clinical utility of the imagery. Related
operational considerations were also examined. This limited review of our CommView system indicates that
the attenuation of the image data by frame-grabbing and inability of the workstation to work with processed
rather than formatted data from computed radiography limits the potential capabilities of the workstation.
The reversible compression algorithm for imagery archival functioned well, but serious high frequency
aliasing was introduced in imagery reduced for transmission to remote viewing stations.
Perception of noise on a PACS display and its influence on signal-to-noise ratio on a film digitizer
R. M. Dawood,
Andrew Todd-Pokropek,
J. O.M.C. Craig,
et al.
Show abstract
The signal to noise ratio and the number of useful bits in data derived from laser film digitization has been
assessed for different film densities. The spot size of 2lOjim was not modifiable, and films were digitized to l2bits
of grey scale. It was found that the useful dynamic range was typically less then 256, and that the least significant
bits were priitiarily noise. This study was part of a series of tests that have been perfonned using resolution patterns,
low contrast objects and clinical test series, from which it appears that noise needs to be perceptible in the image
for good perfonnance in detecting subtle features. Results from the use of the low contrast phantom, comprising
'lesions' of size well above system resolution but with contrasts ranging from greater than to less than the noise
level, indicated that reading from the digital display gave better results than reading from film. It is believed that
this gain in contrast perception resulted from the use of an appropriate window setting on the digital display such
that noise was clearly visible.
Optimal use of rating scales in ROC analysis
R. M. Dawood,
Andrew Todd-Pokropek,
J. O.M.C. Craig,
et al.
Show abstract
Observers participating in ROC studies are usually required to estimate the confidence with which each
observation is made. With a discrete scale, the rating, or score, normally falls into one of 5categories, ranging from
'definitely normal' to 'definitely abnormal'. However, a major problem in data analysis from ROC studies has been
found to be caused by observers who have not used the rating scale in a uniform manner, and have made many
responses corresponding to the two extreme categories with few responses falling in the middle. The use of a
continuous rating scale, with a point selected using a mouse, has assisted in analysis, but only to a limited extent.
It has therefore been suggested elsewhere that it is desirable to force observers to select intermediate points. The
effect of such an approach on ROC curves was studied by asking a group of observers to re-score a set of difficult
clinical images, after training and with continuous feedback on their compliance. Although the resulting fall in the
ROC curves was not statistically significant, it is considered unwise to force observers to report in what to them
appears to be an unnatural manner.