TECHNOLOGY UPDATE

Connectivity .
Teleradiology

and beyond
(Part one)

Connectivity, Teleradiology and
Telemedicine, These are some of the "buzz
words" describingthe latest technology in our
field and, as with any new technology, it has
spawned its own jargon and set of acronyms.
This article aims to explain some of the jargon
and in so doing enhance the levelof discussion
of this important topic.

Why
connectivity?

Throughout the world health care provid-
ers are finding that improved productivity
and efficiency are critical to long term suc-
cess.The use of connectivity has the follow-
ing primary goals:
• Connect existing digital equipment in
order to reduce manual activities and in-
crease departmental efficiency:
• Move images quickly throughout the fa-
dlity to enhance patient care.
• Move image data between facilitiesin or-
der to make use of centres of excellence to
speed diagnosis.
• Integrate image data with diagnostic in-
formation to improve the diagnostic proc-
ess.
• To allow disadvantaged communities
access, via telecommunications, to special-
istcare.

One of the most common terms that is
being bandied about is DICOM. What is
DrCOM and why is it so important?

DrCOM is an acronym for Digital

Imaging and Communications in Medi-
dne.DrCOM wasdevelopedbytheAmeri-
can College of Radiology (ACR) in con-
junction with the National Electrical
Manufacturers' Association (NEMA) in
America. The current version of the stand-
ard is "version 3,0".

We are talking here of connecting two
devices together, and as far as DICOM is
concemed that means we have to describe
both ends of the connection. This leads to
the concept of Service Classes. Service
Classes provide very specific information
about the kinds of images to be exchanged
and the expected operation of the devices
on both ends of the connection. An alter-
native description of a Service dass is a SOP
Class (SOP stands for Service/ObjectPair).
Images are called "objects" and the opera-
tions the device is to perform on the im-
ages are called"services".In addition, devices
daim conformance to a Service Class as ei-
ther a User or a Provider.

By way of another example, laser print -
ers are Providers of the BasicGreyscale Print
Management Service Class.

DrCOM requires the manufacturer to
publish a Conformance Statement for all
devices that claim conformance to the
standard. The Conformance Statement
contains very specific information about
the device. To use the laser printer exam-
ple above, the Conformance Statement
would contain the following information:
• The network on which it operates, for
example TCPIIP over Ethernet
• The Service Class (or Classes) that the
device conforms to, for example Basic
Greyscale Print Managernent (Ibis means
it prints black and white images)
• The range of values supported for vari-
ous functions, for example formats of l-up
to 35-up and that it can print 4096 x 5120
pixels
• Optional functions that are supported,
such as slides

rt will be dear from the above that the
simple statement "DICOM compatible"
doesn't mean very much and that an in-
depth investigation is needed to establish
whether devices will indeed "talk" to each
other and perform useful work

Next we look at
MODEMS and

ISDN
MODEM stands for Modulator
Demodulator. The most common applica-
tion of a modern is the fax machine where
a document is scanned and the informa-
tion (characters and graphics) is modulated

The Service Class
User/Provider .a

Concept

1-------1 ~ ~
1.- =_-'

Although the CT Scanner 'provides" images,
It is a UHr of the Ilorage eervlee provided by
the archive and display system. It thus claims
conformance as a User of the CT Image
Storage Service Class,

The Image archive and display system
claims conformance as a provider of the
CT Image Storage Service Class,

42 SA JOURNAL OF RADIOLOGY. September 1996

to page 43



C()nnectivity .
Teleradiology and beyond (Part 1)

frompage42

onto a tone that can be transmitted down
a conventional telephone line.At the receiv-
ing end the tone is demodulated back into
characters and graphics and printed out.
Standard faxes operate at 9600 bits per sec-
ond (or 9600 Baud). Moderns on comput-
ers that share data or access the Internet can
run at up to 28 800 Baud, however this is
approaching the limit of what a standard
telephone line can handle.

The next generation of telephone lines
will use Integrated Services Digital Net-
work (ISDN). When you pick up your
phone, the dial tone you hear is sent from
your telephone exchange which, in mod-
em areas, is a powerful digital switch. The
switch, in turn, is linked to hundreds of
thousands of high speed digital connections

that are capable of carrying thousands of
voice and data conversations simultane-
ously. The problem comes in with the line
that connects your phone to this network
- it is analog!

As can be appreciated, this may work
well for voice and faxes but when we want
to transfer massive amounts of data (such
as contained in a radiographic image) we are
faced with a very slow system.

ISDN is a fully digital service which al-
lows simultaneous high-speed transfer of
live video, data and fax over a conventional
telephone line. ISDN comprises two types
of communications channels:
B Channels (Bearer Channels]
B Channels are designed to carry virtually
any kind of digital information. They are

normal telephone lines that are capable of
carrying data at 64000 bits per second.

D Ch31U1els (Delta Ch3lU1elS)
D Channels carry call signalling and set-up
information such as the telephone number
of the network. This channel dramatically
speeds up connection time.

Basic Rate
Basic rate ISDN provides the user with two
64Kbps B channels and one 16Kbps D
channel. Basic access represents lSDNin its
simplest form.

Theauthorwishes tv thank the SA. ISDN
Forum, GE Medical, Teemed (Kodak Health
Systems), SA. Philips and Siemens forprovid-
inginformation for this article.

COMPANY NEWS

PI"IILlI'S MEDICAL

Telemedicine -
the diagnostic
information
highway of the
future

Philips Medical Systemsoffer a range of prod-
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expertise. Optimising resource management
by providing professional expertise remotely,
where previously no service was offered, or
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From the 'total concept' approach of a
large investment,single PictureArchivingand
Communication Systems (PACS) of the

] 970s, a phased, modular approach is todays
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quirements. The principle is that transmis-
sion, display, manipulation and storage of
digital images should offer physicians clini-
cal advantages, improve operation of health
care institutions, and ultimately optimise
patient service.

The modular concept facilitates staged
integration of the Radiology Information
System (RIS), the digital information of
MR, CT, anglographic and RIF applica-
tions, cassette based computed radiogra-
phy and remote tele-irnages The evolve-
ment of the DICOM standard for trans-
ferring images and associated information
between digital devices regardless of
manufacturer, provides further expansion
of the integrated modular approach.

43 SA JOURNAL OF RADIOLOGY. September 1996

The Philips "Iele-Imager" teleradiology
system offers custom designed software The
basic system, which can be fully extended
in a modular approach, comprises a capture
station, a viewing station and the transmis-
sion medium. Multiple resolution choic s
from lK2 to 4K.2 filmdigitisationwith 12bit
grey scale imaging, choice of compression
factors and combined with 1600 x 1200
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tic capability. Image transmission can take
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puted radiography provide for an integrated
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For more information, contact your
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