Evans, Damien

Nagy, Paul

Toland, Christopher

Wallace, Bill

Warnock, Max J.

English

PubMed

Max J. Warnock

Christopher Toland

Damien Evans

Bill Wallace

Paul Nagy

Crossref

Benefits of Using the DCM4CHE DICOM Archive

Springer - Publisher Connector

Benefits of Using the DCM4CHE DICOM Archive
Max J. Warnock, Christopher Toland, Damien Evans, Bill Wallace, and Paul Nagy
KEY WORDS: Integrating Health Care Enterprise (IHE),
Digital Imaging and Communications in Medicine
(DICOM), digital image management, PACS administra-
tion, PACS DICOM IHE conformance
INTRODUCTION
W ith advances in digital imaging throughoutthe 1990s and the rapid adoption of Picture
Archiving and Communication Systems (PACS) in
the last decade, standards for information ex-
change have become crucial to effective commu-
nication, both within the radiology department and
with the larger enterprise and outside institutions
and agencies. The original Digital Imaging and
Communications in Medicine1 (DICOM) standard
was introduced in 1993 and, in the intervening
years, has been widely adopted. Interest in
DICOM, as well as the continuous integration of
new technologies and modalities into medical
imaging, has resulted in a series of new and
revised DICOM standards. Along with the grow-
ing complexity of these standards has come a need
for tools that can manipulate and store DICOM
information.
In 2000, responding to these needs, JDicom, a
toolkit written in the Java programming language,
was developed for manipulating DICOM. The
popularity of this new tool kit persuaded its lead
developer to build a full-featured DICOM archive.
The mission of the project was to produce a
DICOM archive that was free, open-source, and
cross-platform and that embraced new directions
being drawn up by the Integrating the Health Care
Enterprise (IHE) initiative. This ambitious goal
attracted more developers, and the DCM4CHE2
project was born. After 7 years of development,
the DCM4CHE project has produced two gener-
ations of a DICOM archive. The current generation
is the result of learned practical experience and
reflects the old programmer’s adage: “Build it
twice, because you will anyway.” This article
reviews DCM4CHE and the DCM4CHE DICOM
archive (DCM4CHEE) and evaluates their matu-
ration as a viable platform for training, integration
testing, and research.
ARCHITECTURE AND FEATURES
The DCM4CHEE architecture was designed to
be modular (Fig. 1), allowing for independent use
of the archive’s services. Each service can be
enabled/disabled using the DCM4CHEE JMX
console (web interface). This modular design also
lightens the load of maintaining old code and
adding new features/services.
1The DICOM Standard web site. Available at http://medical.
nema.org/. Accessed on June 6, 2007.
2The DCM4CHE Project History web site. Available at
http://www.dcm4che.org/confluence/display/proj/history.
Accessed on June 6, 2007.
From the Diagnostic Radiology, University of Maryland
School of Medicine, 22 South Greene Str., Baltimore, MD,
21201, USA.
Correspondence to: Max J. Warnock; e-mail: mwarnock@
umm.edu
Copyright * 2007 by Society for Imaging Informatics in
Medicine
Online publication 5 October 2007
doi: 10.1007/s10278-007-9064-1
Journal of Digital Imaging, Vol 20, Suppl 1, 2007: pp 125Y129 125
As a result of this architecture, DCM4CHEE
features have grown up in pillars, encompassing
the standards [DICOM, Health Level 7 (HL7),
etc.] with which they interact. Individual features
of the archive are listed under their corresponding
standards in Table 1. Each of these services
represents a part of routine workflow in a
radiology department. DCM4CHEE exposes and
uses these services as outlined in IHE.3
DCM4CHE as a Training Platform
Perhaps the most daunting task for any new
PACS administrator is understanding and gaining
experience with the DICOM standard. DICOM is a
binary run-length encoded standard developed
solely for medical imaging and can require
hexadecimal editors merely to read. DICOM is
perhaps the most important single area that a
PACS administrator must master, and this mastery
increases in difficulty as the DICOM standards
grow in numbers and complexity. The most
effective way to learn DICOM is through a
practical, hands-on approach, which DCM4CHEE
provides.
DCM4CHEE is easily set up and includes
comprehensive logging of DICOM transactions.
The archive comes in a precompiled (binary)
version designed for two open-source and readily
available databases, MySQL and POSTGRES. The
package available on sourceforge.net4 comes with
directions for setting up the archive on multiple
4The DCM4CHE project file archive. Available at http://
sourceforge.net/projects/dcm4che/. Accessed on June 6, 2007.
Fig 1. Graphical representation of the modular DCM4CHEE architecture.
3A web site detailing the IHE profiles supported by
DCM4CHEE. Available at http://www.dcm4che.org/confluence/
display/ee2/IHE+Integration+Statement. Accessed on June 6,
2007.
126 WARNOCK
operating systems.5 The depth of the installation
documentation provides one example of the matu-
rity of DCM4CHEE. Its web-based graphical user
interface (GUI) provides the ability to search the
archive and offers a number of other operations
that can be performed without the need of in-depth
DICOM knowledge. The log files allow the user to
view the DICOM transactions produced by the
GUI. By viewing the log of the GUI transactions,
even a novice can glean the required information
for DICOM transactions and, in the process, gain
insight into how the standard works. Setting up
and using the archive and experimenting with the
toolkit is a productive way to gain experience with
the DICOM standard.
As the user’s PACS administration and testing
needs grow more complex, the DICOM toolkit on
which DCM4CHEE is built becomes a valuable
asset. Knowing the DICOM terminology and
having an understanding of how and when
messages are sent opens new perspectives on ways
to validate processes and test the PACS environ-
ment. Although the current documentation for the
tool kit may present some challenges to the novice
administrator, those with DICOM experience will
find it a useful asset. Gaining experience with the
tool kit will not only help in learning DICOM but
can be a critical tool for troubleshooting systems.
Despite the fact that DICOM is a widely
adopted standard for medical imaging, it is not an
all-encompassing solution for integration and
transaction issues in all health care environments.
DCM4CHEE also supports HL7 admission/dis-
charge transfer order, observation results unsolic-
ited, and order management messaging, as well as
syslog audit record messages and ebXML in cross-
document sharing of the IHE. DCM4CHEE’s
compliance with the IHE profiles helps to round
out a PACS administrator’s vision of clinical
workflow in medicine. Having an IHE-compliant
archive with which to experiment provides valu-
able hands-on experience. DCM4CHEE makes
examining each step of the major processes of a
radiology practice straightforward with verbose
logging, as well as an audit record repository
(ARR). These features aid in knowing what should
be happening at each step of clinical workflow and
thereby assist in securing faster diagnoses and
more timely resolutions of future systems failures.
A Workbench for Testing
Because it is designed around IHE, DCM4CHEE
also serves as a platform for testing new and/or
existing applications in clinical systems. When
5The DCM4CHE Project History web site. Available at
http://www.dcm4che.org/confluence/display/proj/history.
Accessed on June 6, 2007.
Table 1. DMC4CHEE Standards and Features
Standard Supported Feature
DICOM C-ECHO SCP/SCU (ping)
C-STORE SCP/SCU (storage)
C-FIND SCP (query)
C-MOVE SCP (retrieve)
N-ACTION SCP/SCU (storage commitment)
Routing of images based on any DICOM tag
General Purpose Worklist SCP
Modality Worklist SCP
Modality Performed Procedure Step SCP
Hanging Protocol SCP
Instance Availability Notification SCU
Teaching File and Clinical Trial Export
Manager
HL7 Inbound ADT (patient demographics)
Inbound ORM (imaging exam orders)
Inbound ORU (diagnostic results)
PIX Query (patient identifier resolution)
Prefetching of DICOM images based on
ORM messages
HL7 message routing
Storage Online: capable of multiple file systems
with MD5 verification of content
Nearline: integration with an HSM or
offline storage system
CD media: media creation manager for
writing to CD
DICOM Dir or date/time-based directory
structure
Web-based
services
HTTP access to DICOM objects and
reports (via WADO and RID services)
Web-based administration user interface
Search for studies
Browse worklists
Configure DICOM destinations
Configuration
View Audit logs
Cross-enterprise
document and
image sharing
(XDS)
Image information source
Document repository
Key object generation source
Auditing Audit logging for all transactions
(according to IHE)
ARR
ADT = admission/discharge transfer order; ORM = order
management; ORU = observation results unsolicited
BENEFITS OF USING THE DCM4CHE DICOM ARCHIVE 127
adding a new modality in the private practice or
hospital setting, DCM4CHEE can be used to test
modality worklist, one of the IHE profiles, outside
of the routine PACS workflow. The Modality
Performed Procedure Step, Cross Patient Identifier
(IHE PIX), and HL7 servers allow for testing of all
the integration features of imaging modalities. As
new PACS vendors appear and established PACS
vendors release new versions, DCM4CHEE can be
used to quickly test for IHE compliance.
DCM4CHEE also comes with an ARR (enabled
by default). An ARR is a log of all transactions
between the archive and other actors, including
modalities, viewers, and other archives. This repos-
itory is viewed and made searchable by the
DCM4CHEE’s web GUI and is a good source of
information on how DICOM transactions are
working in the system. It records detailed informa-
tion about the sources exchanging data, as well as
metadata on the information being sent. When using
the archive, the ARR is a wealth of information
about system utilization and also serves as an
excellent health insurance portability and account-
ability compliance log.
As IHE becomes more pervasive in the health
care industry and other initiatives work to provide
new standards for sharing patient data across the
enterprise, IHE cross-enterprise document sharing
(XDS) profiles will become more important.
DCM4CHE has already incorporated the XDS-I
IHE profile for image sharing into the archive. As
new XDS repositories and sources become avail-
able on the network, these can be tested using the
DCM4CHEE GUI tools for XDS-I. The user can
simply select a study to be sent to the XDS-I
source, select application entity title from the drop-
down list, and click the XDS-I icon. Again, by
examining the log file, the interaction between the
two servers can be seen, as well as any errors that
might have occurred, so that additional configura-
tion can be performed as needed before the XDS
repository is put into production.
Most administrators fear changes in their sys-
tems. “If it’s not broke, don’t fix it” is the general
attitude and understandably so. PACS is no longer
a novelty but a mission-critical driver in medical
imaging workflow. Administrators do not have the
luxury of letting the system fail today and
worrying about fixes tomorrow. A key part of all
proactive change management is proper testing.
DCM4CHEE can be used for a substantial portion
of the testing required to ensure stability of clinical
systems.
Teaching Archive and Research Platform
In many departments, research and teaching
activities are second-tier funding considerations,
budgeted separately from (and much less liberally
than) clinical systems. Because DCM4CHEE is
both free and stable, it can be used as an archive at
the cost of the hardware on which it runs. The true
value of today’s growing number of electronic
teaching/research files lies not in the DICOM
study alone but also in the annotations, key
images, and presentation state. IHE has defined
the Teaching File and Clinical Export (TCE)
profile, which includes a standardized way for
PACS systems to share this information.
DCM4CHEE supports importing DICOM, key
object notes, annotations, and associated docu-
ments as outlined in the TCE profile. A radiologist
can annotate a study in a PACS that supports the
TCE profile and export it directly to a
DCM4CHEE research database, retaining all the
pertinent information – as well as customized
teaching notes – provided by the radiologist.
Moreover, the research archive’s database can be
queried to gain additional insight into and identify
patterns in the metadata associated with research
studies. An added benefit of using a research
archive is that there is no degradation in the
performance of the clinical PACS when research-
ers retrieve studies or perform complex database
queries. Segregating studies into a research archive
ensures good performance and provides a test bed
for faster and easier research.
Simple study segregation and querying of the
archive are not the only types of research that can
be performed using DCM4CHEE. The archive can
be used as a foundation for PACS-based product
development. One example of a project using
DCM4CHEE as a base for testing and develop-
ment is Xero, a truly thin-client viewer for medical
imaging.6 The primary goal of Xero is to have a
full-featured PACS viewer that works in any major
web browser without additional plug-ins or pro-
grams installed on the client. Xero utilizes web
access for DICOM objects (WADO) and web
6The web site for the Xero project. Available at http://www.
dcm4che.org/confluence/display/ee2/Xero. Accessed on June 6,
2007.
128 WARNOCK
technologies such as asynchronous JavaScript and
XML (AJAX). WADO is a standardized way of
sending DICOM objects over hypertext transfer
protocol (HTTP). The standard allows DICOM
images or parts of images to be sent upon request.
By using AJAX to make HTTP requests without
refreshing the web page, Xero provides native, in-
browser, window/level, pan/zoom, and stacking
features for viewing images. Xero is being devel-
oped using DCM4CHEE as a DICOM archive and
uses the DCM4CHE toolkit for many of its
internal tasks. However, the product is not tied to
DCM4CHEE because it integrates using the
WADO standard. Any IHE-compliant archive with
a WADO cache can be the source for the Xero
viewer.
Using DCM4CHE as a base server for IHE-
driven health care products is a major benefit to
researchers and developers. It allows them to focus
on their products rather than being forced to build
proprietary archives for testing, an approach that
can lead to optimizations that make the initial
product dependent on the ad hoc archives and stray
from IHE initiatives.
As a result of open-source tools and intense
community-based interest in the relevant stand-
ards, many projects are utilizing DCM4CHE.7
These ancillary communities ensure the continued
success of DCM4CHE by building up the com-
munity of users, contributing to documentation,
and creating experts who can teach the next
generation of PACS administrators and researchers.
A Community of Support
As with all open source projects, the success and
adoption of DCM4CHE depend on the community
surrounding the code. The DCM4CHE community
has an active core team of developers and
continues to gain support in the form of bug fixes,
wiki pages, and mailing list posts.
The wiki8 is a good source of information for
getting started with DCM4CHE and in understand-
ing the intricacies of the archive and toolkit.
However, when looking for help, it is important
to remember that the wiki is neither a tutorial nor a
forum. It does not have a simple sitemap or
navigation but, instead, is driven primarily by the
search feature. When troubleshooting or looking for
answers, it may bemost helpful to consult thewiki first.
For more active support on points not well
documented, the user should turn to the mailing
list.9 This electronic list is quite active, and queries
usually receive quick responses. One benefit of
having a worldwide community is that assistance
is available at any time, day or night. Subscribing
to the mailing list also allows the user to contribute
to the community by helping others with problems.
By following the mailing list, users may also find
answers to problems that have not yet been
addressed in their own systems. Users may also
participate by creating new pages on the
DCM4CHE wiki with their own solutions for
common problems. Code is not the only contribu-
tion that is made in the open-source community.
The synergistic act of simply participating as a
user in the DCM4CHE project is one method of
support, and this support can be extended by
contributing advice based on experience in the
form of wiki pages and assistance to less experi-
enced users on the mailing list.
CONCLUSION
The DCM4CHE project has survived and
prospered to produce a powerful, stable, and
feature-rich archive. It is a tool with which both
PACS administrators and researchers should be
familiar. It is a major building block with which
the health care community can work to fix
problems, learn standards, and challenge vendors
to become better integrated and more open. The
future focus of DCM4CHE will be shaped entirely
by the experience and feedback of its users. This
participatory growth is likely to produce an even
more useful and flexible platform.
ACKNOWLEDGMENT
I would like to thank Dr. Nancy Knight from the University
of Maryland School of Medicine for her assistance in preparing
this manuscript.
9The DCM4CHE mailing list subscription web site. Avail-
able at http://sourceforge.net/mail/?group_id=37982. Accessed
on June 6, 2007.
8The DCM4CHE Wiki. Available at http://www.dcm4che.
org/confluence/display/proj/The+Project. Accessed on June 6,
2007.
7Listing of DCM4CHE based projects and users. Available at
http://www.dcm4che.org/confluence/pages/viewpage.action?
pageId=393. Accessed on June 6, 2007.
BENEFITS OF USING THE DCM4CHE DICOM ARCHIVE 129


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