Digital Imaging and Communications in Medicine (DICOM)

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Chapter 4 A Brief History of DICOM
make digital medical imaging independent of particular device manufacturers,
thus facilitating the expansion of digital imaging and PACS. If we look at
several other industries that are currently struggling with compliance issues,
we should admire the foresight of those who reflected upon the structure of
digital medical applications long before the spread of contemporary computers
and networks.
The joint committee, named the ACR-NEMA Digital Imaging and Communications
Standards Committee, began its work by reviewing many other
standards established at that time. Although the committee found nothing specifically
fitting for its needs (Horill et al. 2004), it did glean a few valuable hints
from the study. The American Association of Physicists in Medicine (AAPM)
had recently adopted a standard for recording images on magnetic tape. The
AAPM was taking the approach of encoding all information as sequences of
data elements, whereby each element could have a variable length (size) and
was identified by its unique name (tag). This idea of representing the data as
a sequence of tagged data elements was adopted by the ACR-NEMA group. If
you have any experience with hypertext markup language (HTML) and better
extensible markup language (XML), you should immediately recognize the
same approach in those very current and very popular standards. The concept
of using data elements as small building blocks to represent data of any complexity
has proven to be extremely useful and robust (Fig. 4).
The first version of the standard, called ACR-NEMA 300-1985 or ACR-
NEMA 1.0, was published in 1985 and distributed at the Radiological Society
of North America (RSNA) annual meeting. Officially, the original ACR-NEMA
standard was proposed as a guideline and NEMA did not assume any responsibility
for its enforcement or interpretation. 6 The objectives for standardization,
however, were well-set and necessary, and compliance with the standard has
become the de facto imperative for the medical community.
As with any first version, ACR-NEMA 1.0 contained errors and imperfections.
It was soon realized that the standard required further work with
continuous effort and better structure. For these reasons, ACR-NEMA embraced
the idea of working groups (WGs), which are separate subcommittees
dedicated to improving specific parts of the growing standard. The first WG
VI (currently known as WG-06, Base Standard) was created to work on improving
ACR-NEMA 1.0. The result of this work was the second revised version,
ACR-NEMA 2.0 (or ACR-NEMA 300-1988), which was released in 1988.
The revised version was sturdy enough to be adopted by the medical device
manufacturers, and slowly but surely it started to work its way into medical
6 As noted in the current edition of the standard: “NEMA has no power, nor does
it undertake to police or enforce compliance with the contents of this document.
NEMA does not certify, test, or inspect products, designs, or installations for safety
or health purposes.”