Digital Imaging and Communications in Medicine (DICOM)

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Chapter 12 Incompatibility of Compatible
to a certain obscurity and interpretation freedom when it comes to real-world
implementation.
As the DICOM standard wisely suggests in its PS3.1:
“Anyone using this document should rely on his or her own independent
judgment or, as appropriate, seek the advice of a competent professional in determining
the exercise of reasonable care in any given circumstances.”
Besides, there are no “DICOM Police”, and all DICOM companies are left to
their own devices. As a result, the inconsistencies in DICOM implementations
from different providers often reflect this lack of DICOM training, as well as
the lack of a competent professional.
The way DICOM is organized also only adds to this discord. Currently,
DICOM includes 16 volumes (from 1 to 18, volumes 9 and 13 retired), and several
hundred supplements. When company X creates its DICOM application it
never implements the entire standard; this would be an enormous and nearly
impossible task. Instead, for its MRI unit, X would pick a very limited subset
of DICOM MR-related functions. The scope of this implementation will be reflected
in the unit’s DICOM Conformance Statement. The correctness of this
statement and the choice of functionality will entirely depend on the competence
of its author. As we mentioned, NEMA does not monitor, test, or in any
way certify the manufacturers’ DICOM compliance. Therefore, it is always between
you, the manufacturer, and 16 DICOM volumes to establish the truth.
My suggestion: always review the DICOM Conformance Statement with
your PACS/DICOM expert before you even think about purchasing any particular
unit or application. This is the only documentation expected to provide
a DICOM-conformant description of the application features, and this greatly
affects the application ability to be integrated with other DICOM applications
and devices. You need to match the list of SOP classes from the statement in
question to the list of SOP classes for your existing devices. If there is no match,
the devices simply will not connect, regardless of how DICOM-compliant each
of them is.
12.2
Testing, Testing, and Yes, More Testing
The conformance statement looks perfect and you invite your company X guru
to come and install the MR scanner, connecting it to the existing Y archive. In
fact, you even ask X’s salesman: “Have you worked with Y before?”. “Certainly!”
he replies, “and our developers like each other, and some of them even went to
school together! No problem!” 37 Then, field engineers from X install the scanner,
plug it into Y, try to send a few images across and – nothing happens.
“Well, we really do the install only, we do not do DICOM”, reply the engineers
37 As always, I am not making this up. It did happen. I am not even being sarcastic.