Web technologies include a multitude of different technologies, which are in common use over the Internet. The author defines pertinent terms and addresses these techologies and their application to clinical image management.
Mr. Margolin is the Vice President of Marketing for
Algotec, Inc., Duluth, GA.
[Editor's note: This article is presented as a counterpoint to
the article, Web technology and its relevance to PACS and
teleradiology by Wayne T. DeJarnette, PhD, published in the August
2000 issue of Applied Radiology, pages 9-12. Applied Radiology
welcomes articles contributing to the dialogue regarding the state
of radiology practice and the use of new technology.]
Though the terms "Web" and "the Internet" are often used
synonymously with their enabling technologies, I agree with Dr.
DeJarnette's position that some distinction between these terms is
important in understanding and analyzing their relevance to PACS
and teleradiology. In my opinion, though, a primary distinction
should be made between Web technologies and the Internet. Web
technologies include a multitude of different technologies, all of
which are in common use over "the Internet"a global, public
network, also known as the "information superhighway."
To clarify the above distinction, here are some
1) E-mail technology has been widely used over the Internet for
more than a decade as a means for information exchange and
communication. In recent years, there has been growing use of
e-mail technology, clearly a Web-related technology, for
intra-organizational communications. In this application, e-mail
messages will typically move on the organization's local area
network (LAN), without ever crossing the public Internet. Still Web
technology based, the application can then be referred to as an
"intranet application," i.e., an application of Web technology over
2) Java technology was introduced in the mid-1990s by Sun
Microsystems as a tool to write platform-independent software code.
In other words, with Java, code can be written and compiled only
once, and then run on any machine, irrespective of its architecture
or operating system. Though Java can be used as any other
object-oriented programming language (e.g., C++) to code software
applications, it is easy to understand its special benefits for
applications that run in the context of the Internet. Clearly, on
the Internet, many different target computers coexist, and the
original application developer has no means to reach all of them or
even anticipate their make or model. Therefore, it is not
surprising that Java has become one of the most common programming
languages for Internet applications. Hence, unlike C++, we can
safely consider Java a Web technology.
Web technology in PACS and teleradiology
In his article, Dr. DeJarnette suggests that different Web
technologies have not been equally useful for PACS and
teleradiology applications. Clearly, no one can dispute the
usefulness of technologies such as TCP/IP communications (which
provide the foundation for the DICOM-3 standard) and the Internet
(with its widely available, low-cost communication infrastructure).
But it is exactly at this point that Dr. DeJarnette's arguments
become entangled. He goes on to say that other Web technologies
have much more limited use or no use whatsoever in PACS and
teleradiology. In my opinion, almost all Web technologies can and
will be useful for these applications. The grounds for this general
statement had best be laid by the distinction made above between
Web technologies and the Internet.
As defined above, what Web technologies have in common is their
usefulness for Internet applications. In other words, these are
technologies that either enable applications to run over the
Internet, or make use of the Internet. This definition includes one
fundamental advantage of Web technologies for PACS and
teleradiology. In fact, I would argue that this definition shows
that the future of PACS and teleradiology is immersed in Web
technologies. To understand why, let us first step back a little
into the history of PACS and teleradiology.
"Traditional" PACS applications, which started in the early
1990s, were all focused on solving the departmental issue of
digital clinical image management. These applications were
hardware- and network-intensive, and could by no means tackle the
much larger problem of enterprise-wide clinical image distribution.
Accordingly, these applications, without exception, were met with
commercial failure. Since films were still needed to complete the
life cycle of the imaging study outside the Radiology department,
cost justification of PACS became practically impossible.
"Traditional" teleradiology applications, by far more
commercially successful than their contemporary PACS applications,
have found their success through a much narrower definition of the
problem they sought to solve. The "traditional" teleradiology
problem entailed images that were acquired at point A, with a need
for interpretation by a doctor at point B. If it is less expensive
to transport the images from point A to point B than to transport
the doctor the other way, "traditional" teleradiology is
appropriate. Under this simple paradigm, "traditional"
teleradiology found its application in the market. But what happens
if the attending physician happens to be at point C; or if there
are multiple attending physicians to review the images? With these
and similar questions, the "traditional" teleradiology paradigm
starts to break down. The application of teleradiology has thus
remained extremely limited relative to its potential market.
First, the basic question: "What is the Internet?" must be
addressed. In his article, Dr. DeJarnette defines the Internet as
"a publicly owned, network-based communication infrastructure that
grew out of DARPA (Defense Advanced Research Project Agency)
research in the 1970s and 1980s." Clearly, this communication
infrastructure has taken a leap in the 1990s, becoming more and
more of an all-encompassing, global network, where people
throughout the world find information, communicate, buy, sell, and
seek entertainment. Now consumer-oriented, the Internet has become
more widely available, faster, and cheaper to attain than any
communication infrastructure ever before.
The "Internet Revolution" of the 1990s has paved the road for a
multitude of new business models and markets, collectively referred
to as "e-businesses." With a good deal of hype, and the help of
some sharp copywriters, fields like e-travel, e-commerce,
e-healthcare, and many others have emerged. Among these, it has
become increasingly clear that the place of e-radiology will not
remain absent for long. But what is e-radiology and what promise
does it hold for the future of radiology?
The answers to the above questions bring us back to the
breakdown of "traditional" PACS and teleradiology. These
applications remained limited because they could not break out from
the confines of the department (in the case of PACS) or some
predefined points A and B (in the case of teleradiology). But what
if a global network is available with enough bandwidth to support
these data-intensive applications and at a price everyone can
afford? The outcome is simple: a new type of PACS and teleradiology
applications, fit for enterprise-wide clinical image sharing and
community-wide or even worldwide radiology consultation and other
remote services. Hence the new business of e-radiology.
It is clear that the Internet has great potential to
revolutionize or reinvent the business of radiology. But this alone
does not explain the usefulness of Web technologies for PACS and
teleradiology applications. As Dr. DeJarnette suggests, it is not
impossible to run non-Web applications over the Internet. The only
question here is: at what cost?
Low-cost Web technologyA myth or a fact?
As defined above, Web technologies either enable the Internet or
make use of it. As such, they create an infrastructure for the
development of applications designed to run over the Internet. The
same two Web technologies mentioned have potential applications for
clinical image management:
1) E-mail has recently been proposed by some vendors as a tool
for the distribution of clinical results, including the
transmission of radiology reports and reference (or key) images to
referring physicians. Clearly a Web technology - why is e-mail
suitable for this task? Here are some good reasons:
a) E-mail systems are prevalent and standard; they do not
require any special application software on the referring doctor's
computer. Therefore, there is one less application to purchase,
install, and maintain on the doctor's computer.
b) Many doctors are very familiar with e-mail, which enables
faster learning curves and lower training and education costs.
c) E-mail messages inherently consist of multimedia contents;
this makes them ideal to transport multimedia clinical results.
d) E-mail systems are highly integrated with Web browser
technology, which opens the way for a closer, smoother integration
of clinical results with more sophisticated and specialized
applications for their processing and analysis.
2) Java has conquered more and more ground as a prime software
development tool in general and in PACS and teleradiology
applications in particular. Dr. DeJarnette declares that Java
"should be of no interest to a PACS or teleradiology user or
purchaser, other than if the use of this technology results in a
more reliable, more maintainable, higher performing, and/or lower
cost system." I totally agree, but I maintain that Java has
tremendous potential to provide exactly that: a lower cost system.
Here are some of the reasons in the specific context of (on-call)
a) Java provides a framework for remote, platform-independent
application use. With a pure Java application, or applet, no
application software whatsoever is required on the end-user's
station to run the application. Everything needed is downloaded
automatically and transparently from the application Web server.
This means that any doctor can operate a Java-based image viewing
application from his/her home PC (using any make and model) as is!
No need to purchase, install, or maintain any application software
on the home PC, since none is required in the first place!
It can be argued that some non-Java applications may be less
expensive than the Java-based ones because the image viewing
application itself is very cheap, or even provided for free
("freeware"), whereas the cost for a Java-based system is in
purchasing the server. I contend, however, that even in the case of
freeware, these applications end up being more costly than the
Java-based ones due to the associated costs of installation and
maintenance. The latter must not be underestimated. General
statistics in the United States show that an organization spends
approximately $1500 annually on the maintenance of each of its PCs.
This amount is comparable to the original purchase price of the PC
itself. Though similar statistics for the consumer market is harder
to obtain, many of us have witnessed first-hand the ramifications
of an operating system upgrade, or even the installation of new
application software, on the performance and viability of other
applications. With Java, these concerns and costs are largely
b) Typically, Java is invoked from a standard Web browser. With
its widely familiar interface, the Web browser thus becomes the
access mechanism for the doctor onto the teleradiology application.
Again, this translates into shorter learning curves and lower
c) Java is easy to integrate with other Web-based technologies
and systems. A Java-based teleradiology application, providing
clinical image viewing capabilities and tools, can easily be
integrated into a Web-based clinical results browser (e.g., patient
charts viewer) or an electronic medical records (EMR) system.
These two examples demonstrate that the low-cost nature of Web
technologies is not only an "article of faith," as suggested by Dr.
DeJarnette. It is based on actual facts.
DICOM and Web technologies: A contradiction in
Dr. DeJarnette makes a distinction between DICOM-based
teleradiology systems and Web-based teleradiology systems. In fact,
he even provides a comparison chart between the two. But, are these
two technologies really mutually exclusive? The answer is
definitely no. There is no reason why these two technologies cannot
be mixed. In fact, some applications in the market today offer
exactly this mix. The concept is straightforward: enjoy the
benefits of both technologies.
How can DICOM and the Web work in concert to provide the best of
all worlds for teleradiology? Here is a simple recipe:
1) The end-user (e.g., a radiologist on call using his home
desktop PC) opens a Web browser exactly as if surfing the Web.
2) The user then selects an IP address (or jumps to a predefined
bookmark) of a teleradiology Web server.
3) The user's Web browser and the server communicate via the
HTTP protocol to initiate the communications.
4) Once the user is authenticated, control is transferred to a
Java applet, which goes from the server to the browser.
5) Through the Java applet, the user can query any DICOM device
on the network and retrieve images from it to the browser. The
DICOM commands are encapsulated in the Web protocol for the
communications between the client and the Web server. Direct DICOM
communications prevail between the Web server (which can also act a
DICOM device) and the other DICOM devices on the LAN.
Pulling, pushing, and compressing on the Web
Another disadvantage of Web technology, according to Dr.
DeJarnette, is its lack of support for the push model: the
traditional teleradiology model. But does the Web really preclude
the use of the push model? The answer is clearly no. First, we
already mentioned e-mail as an obvious example of Web technologies.
E-mail is also a push-type of technology. As mentioned above, I see
the main application for e-mail in the distribution of clinical
results to referring physicians. E-mail remains limited in its
application for teleradiology, i.e., remote interpretation of
But e-mail is not the only push-type Web technology. There are
other technologies available that allow pushing data to the user as
opposed to having them pull this data. In fact, some commercial
Web-based systems make use of such technologies in the context of
PACS and teleradiology applications today. The main benefit of the
push model is in cutting short the waiting time for the data to
download. When used over slow communications (e.g., plain old
telephone system), this model can make a significant difference,
especially for the radiologist on call. But, since it is available
on both Web and non-Web systems, this cannot be taken as a
differentiation between the two.
When dealing with slow communications, the push model is only
one option. Another important factor is compression. Dr. DeJarnette
claims that Web systems generally offer only JPEG compression,
which has been known to be inferior to Wavelet compression
techniques in handling clinical images. While this may be the case,
since JPEG is so commonly used on Web pages, it must be noted that
nothing on the Web prevents the use of Wavelet compression. And
again, some commercial Web systems already offer Wavelet
Moreover, by making use of the concept of progressive
compression prevalent on Web pages, some Web systems actually
reduce the user's waiting times even more. The concept is simple
and powerful: images are first loaded and displayed in crude,
low-resolution versions, which come up very quickly. The images
then build up their resolution to show more and more of the fine
details, while the user already has access to most of the data.
Web without Internet?
Highlighting the benefits of the Internet, Dr. DeJarnette
mentions that non-Web systems can make use of this global network.
He also mentions that the Internet still has its drawbacks,
including bandwidth and security questions. I agree with him on
both points. I believe, however, that the complete picture must be
examined in context.
As explained above, I believe a primary distinction must be made
between the Internet and the Web, i.e., Web technologies. We must
understand that there are four generally possible combinations for
using the Internet and/or Web technologies (Table 1). In other
words, some non-Web systems can run over the Internet. Most
Web-based systems can also run over any communications that support
TCP/IP. In particular, the application of Web-based systems over
LAN is common, and is referred to as an "intranet application."
Intranet applications offer the benefits of Web technologies
without the concerns associated with the public Internet. Since the
application runs on a dedicated, private network, bandwidth and
security are no longer serious hurdles. Here are some benefits to
Web technologies running without the Internet:
* Open, standards-based architecture
* Common user interface (e.g., through the Web browser)
* Platform independence (e.g., through Java)
* Excellent scalability (consider the basic model of the
One additional major benefit of Web technologies is their easy
expandability onto the Internet. Even in cases in which the
Internet cannot be used today, e.g., due to bandwidth limitations
or security concerns, it would be unwise to preclude the use of the
Internet in the future: when bandwidth becomes more readily
available, or when sufficient security measures are in place.
In fact, on both the bandwidth and security questions, it would
be extremely shortsighted to ignore the development of the market
in recent years. High-speed Internet connections, through cable
modems and digital subscriber lines (DSL) are reaching more and
more of the consumer market, while encryption techniques and their
derivative virtual private networks offer excellent privacy and
data protection over the Internet. Far from having PACS or
teleradiology in mind, these prominent market trends pave the road
for more use of the Internet for these applications. Since they
were originally designed to enable applications running on the
Internet, Web technologies provide the best guarantee for smoothly
and simply migrating new applications to the Internet. An
application can begin by running on an intranet and then be
expanded to the Internet when the need arises.
PACS, teleradiology, EMR and the promise of Web
For many years, PACS and teleradiology have been considered two
separate applications. I contend that this distinction becomes
unnecessary from a technology standpoint with the introduction of
Web technologies. My argument is simple: no one can deny the need
for PACS to expand its reach toward the larger community of
referring physicians. As I argued above, this is exactly where
"traditional" PACS failed. Web-based PACS, on the other hand, offer
the first economically viable solution for this need. While most
referring physicians will settle for what Dr. DeJarnette calls "the
simple Web-server-based teleradiology model" (i.e., sending reports
and reference-quality images using HTML pages), in up to 30% of
cases (e.g., for neurosurgery and orthopedic applications), the
image viewing capabilities required are not any different than for
teleradiology. Luckily, Web technologies can address well the needs
in both cases. If the physician at the end of the line happens to
be a radiologist, we're back to the teleradiology application. In
other words, with a Web-based PACS, which addresses the needs of
the referring physician community, teleradiology becomes almost an
inherent side effect. There is no need to invest in a separate
This consolidation of PACS and teleradiology has more
far-reaching implications. In my opinion, it is only one facet of
the much larger potential of the Web for integrating different
applications. Perhaps the most interesting of these in the context
of PACS and teleradiology is the potential for creating
comprehensive EMRs. Long sought for, and still almost non-existent,
the EMR can be thought of as a global access engine, available
everywhere, and providing a uniform interface to comprehensive,
multimedia clinical information on a patient. It is not hard to see
the potential of the Web browser in this context. In fact, some
precursors of this integration are already available. Interestingly
enough, it is via Web-based applications that clinical images can
be accessed from some radiology information systems (RIS) and other
clinical information systems (CIS) today. Simply put, the Web
provides common grounds for the unification of these, previously
Choosing between Web- and non-Web-based systems
Dr. DeJarnette says that "in order to decide whether or not to
choose a Web-based system, it is important to understand the
details of the application. In the end, the choice should come down
to: which system addresses identified needs, as well as anticipated
future needs, at the lowest cost." I could not agree more. I
contend, however, that in most cases the Web system will in fact
offer exactly that: better handling of present and future needs at
a lower cost.
Dr. DeJarnette concludes: "Al-though interesting and well hyped,
the use of Web technology should not be the sole basis for deciding
on the purchase of PACS and teleradiology systems. The technology
employed in a medical imaging product should be one of many factors
considered as part of the purchasing decision." I agree completely.
He then continues: "In PACS and teleradiology applications, Web
technology has no de-facto advantage." As I demonstrated above,
this is definitely not true. Web technology offers some very clear
and prominent advantages. With these in mind, I would recommend to
anyone interested in PACS or teleradiology, at a minimum, to
consider these technologies seriously and without prejudice. Of
course, no one can contest Dr. DeJarnette's bottom line: "As with
any system purchase, no decision should be made without thoughtful
consideration of the application itself and how well it meets the
needs of the radiology department." But nothing in this statement
can diminish the huge promise of Web technologies for clinical
image management. AR