Using an open source PACS solution instead of a
commercial PACS could be attractive to
LMIC (Low and Middle Income
Countries) as it provides a good start to gain experience with managing digital
medical images with a relatively low entry cost. In this paper we’ll discuss
the PACS features that can be offered by open source providers, implementations
strategies, and lessons learned.
Why would someone want to use an open source
PACS?
· The most important reason is its lower cost as
it is free (kind of), i.e. there are no software and/or licensing fees. The
exception is for the operating system, which can be open source as well if one
uses Linux or a variant, and, if applicable, other utilities such as a
commercial database, but again, they can be an open source product as well.
There is a significant cost involved for the hardware, i.e. servers, PC’s,
medical grade monitors for the radiologists and the network infrastructure,
i.e. cabling, routers and switches. The latter assumes that there is not a
reliable network in place which is often the case in LMIC’s, therefore, a
dedicated network is often a requirement.
· Open source PACS allows an organization to find
out what they need as they are changing from using hardcopy films to a digital
environment with which they have often no experience and/or exposure. As many
open source PACS systems have a free and commercial version, it is easy to
migrate at a later date to the paid version, which provides the upgrades and
support as the organization feels comfortable with the vendor.
· This is not only applicable to LMIC regions, but
an open source PACS can be used to address a missing feature in your current
system. For example, they can be used as a DICOM router.
· The open source PACS can function as a free
back-up in case the commercial production PACS goes down as part of an
unscheduled or scheduled downtime.
· It can be used as a “test-PACS” for
troubleshooting, diagnostics and training.
But the main reason is still the cost advantage.
If a LMIC hospital has to choose between a purchasing a used CT or MRI for
let’s say $350k US, which could have a major impact on patient care as it might
be the only one in a large region serving a big population,
and investing in a PACS system, the choice is clear: they will first
get the modality and then use maybe another $50k or so to buy the hardware
servers, PC’s and monitors and string cable to get a network in place and
install an open source PACS. One should also be aware that the argument of not
having any vendor support for an open source PACS is grossly over-rated. I have
seen some good dealers and support but also some very poor service engineers,
so even if you would use a commercial PACS, the chance that you get any decent
support is often slim in the LMIC region.
Let’s now talk about the PACS architecture as
there is a difference between a “bare-bones” (BB-PACS), a typical (T-PACS) and
a fully featured (FF-PACS). This is important as in many cases you might only
need a BBPACS to meet the immediate needs in a LMIC hospital or clinic.
A TPACS takes in images from different
modalities, indexes them in a database, aka Image Manager, archives them in
such a way that they can be returned to users, and provides a workflow manager
to allow for multiple radiology users to simultaneously access the studies
using different worklist criteria. For example, the workflow manager would
allow the studies to be accessed using different specialties (neuro, ,
pediatrics) and/or body parts (extremities, breast, head) as a filter while
indicating if a study is being read by someone else, its priority, and if it
has been reported. The TPACS also has a tight integration with its
workstations, the PACS archive, and database through the workflow manager, i.e.
these workstations would typically be from the same vendor that provides the
PACS archive and database.
The FF-PACS would be a T-PACS and also have
reporting capability, preferably using Voice Recognition and a Modality
Worklist Provider that interfaces with the digital modalities with an ordering
system to allow the technologist at the modality to pick from a list instead of
having to re-enter the patient demographics and selecting the appropriate
study.
A BB-PACS would be merely a PACS database and
archive. It would not have a workflow manager and one could use an open source
workstation from another vendor. Almost all open source PACS systems are of the
BB-PACS kind, which means that one has to select a preferable open source
viewer with it as well.
How are these open source PACS systems
implemented? In the developed world, it typically happens top-down, i.e. a
hospital has a Radiology Information System (RIS) that places the orders, which
is replaced in most institutions by an ordering feature in the EMR. These
orders are than converted from a HL7 into a DICOM worklist format by a Worklist
provider. The images that are being acquired are sent to the PACS and the
radiologist uses a Voice Recognition System to create the reports.
In the LMIC regions, it typically starts
bottom-up. The first step is converting the modalities from film to digital by
replacing their film processors with CR reader technology or upgrading their
x-ray systems to include a Direct Digital Detector. They might get a CT and/or MRI
that also prints studies on a film printer. They now have digital images that
need to be viewed on a viewing station, archived and managed, therefore a PACS
is needed. That is when the vendors start pitching their commercial PACS
products, usually a FF-PACS or T-PACS, which are typically unaffordable, hence
the choice to implement an open source, BB-PACS with a couple of open source
view stations.
It is critical at this point to use a medical
grade monitor for the radiologist to make a diagnosis as commercial grade
monitors are not calibrated to map each image pixel value into a greyscale
value that can be distinguished by a user. These monitors do not need to have
the high resolution (3MP or 5MP) as is commonly used in developed countries,
but a 2MP will suffice, knowing that to see the full resolution the user will
have to zoom in or pan the image in a higher resolution. These 2MP monitors are
at least three or more times less expensive than their high-resolution
versions. The only disadvantage is that they require a little bit more time for
the interpretation to be done as the user has to zoom to see the full spatial
resolution.
After having installed a BB-PACS and used it for
a few years, the institution will have a better idea of what their specific requirements
are for the PACS system and they can make a much better decision for what they
want to do next. There are three options:
1. Expand the current open source BB-PACS, e.g.
upgrade the storage capacity, replace the server, have a more robust back-up
solution and add a commercial workstation workflow manager, a Modality Worklist
Provider and reporting system. This assumes there is a mechanism to enter
orders, i.e. through a RIS or EMR.
2. Keep the BB-PACS and turn it into a Vendor
Neutral Archive (VNA) and purchase a commercial T-PACS which serves as a front
end to the radiologist. The new PACS might store images for 3-6 months and the
“old” PACS will function as the permanent archive.
3. Replace the BB-PACS with a commercial T-PACS or
even a FF-PACS assuming the funds are available and you are looking for a cost
effective solution.
Note that the advantage of option 1 and 2 is
that you don’t need to migrate the images from the old to the new PACS, which
can be a lengthy and potential costly endeavor.
What are some of the open source PACS systems?
The most common options are Conquest, ClearCanvas server, Orthanc, DCM4CHEE and
its variant Dicoogle. Conquest and ClearCanvas are Windows based, Orthanc can
be both Windows or Linux and DCM4CHEE is Linux based. Conquest is the most
popular for being used as a router and for research and the easiest to install
(literally a few minutes). ClearCanvas is also relatively easy to install,
DCM4CHEE is the most involved but there is now a docker available that makes
the process easier. DCM4CHEE is also the most scalable. For open source
viewers, one can use the ClearCanvas viewer, which is the most popular, or a
web-based viewer such as Oviyam with DCM4CHEE. RadiAnt is another option and
Osirix is the primary choice for a MAC. There are several other options for
viewers, one can do a search and try them out, but be aware that they differ
greatly with regard to functionality and robustness. Another consideration is
continuing support, as an example, the gold standard for the open source viewer
used to be E-film, but that company was acquiredby a commercial vendor who
stopped supporting the open source version which is a problem with the frequent
OS upgrades especially when based on Windows.
What are some of the lessons learned with
installing the open source PACS:
· Be prepared to assign an in-house IT and/or
clinical person who is computer literate to support the PACS. This person will
be responsible for day-to-day support, back-ups, managing scheduled and
unscheduled downtimes, adding additional modalities and interfaces with a RIS,
EMR or reporting system as they are being introduced. This staff member will
also be responsible for troubleshooting any issues that might occur. They will
also be the go-to person for questions about its usage and he or she will train
incoming users. These so-called PACS administrators are a well-established
profession in the developed world, but it will be a challenge initially to
justify a designated position for these people to the department and hospital
administration in the LMIC region as it is a new position.
· How will these PACS administrators get their
knowledge? There are fortunately many on-line resources, including on-line
training, and organizations such as RAD-aid, which has been conducting PACS bootcamp
training session in LMIC regions to educate these professionals.
· PACS is a mission critical resource that has
impact on the infrastructure (power, network, HVAC, etc.). In most cases the
existing network is not secure and reliable enough and/or does not have
sufficient bandwidth, which requires a dedicated network with its own switches
and routers.
· It is preferred to use locally sourced hardware
for the IT components to allow for a service contract and access to parts. The
only problem you might have is to get medical grade monitors in some regions as
they are not as popular yet.
· Pay attention to the reading environment for
diagnostics, I had to instruct people to switch off their lightboxes that were
used to look at old films and even paint some outside windows to reduce the
ambient light. Use medical grade monitors for diagnostic reading.
· Use good IT practices that includes implementing
cyber security measures, reliable back-up and OS patch management.
· Create a set of Policies and Procedures for the
PACS that include access control, who can import and export data on CD’s and
how that is done, unscheduled and scheduled down-time procedures, and
everything else needed to manage a relatively complex healthcare imaging and IT
system.
In conclusion, open source PACS systems are a
very viable, if not the only option due to cost constraints, in LMIC regions,
especially for the first phase. One should be aware that these open source PACS
systems are very much a bare bones solution with limited functionality, however
they allow the user to get started and find out their specific requirements. If
additional funds become available, one can upgrade later to enhance
functionality or replace it with a commercial PACS which can become either
“front-end” to the existing PACS or a replacement.
Resources:
Conquest: https://ingenium.home.xs4all.nl/dicom.html
Dcm4chee: https://www.dcm4che.org/
Orthanc: https://www.orthanc-server.com/
ClearCanvas: http://clearcanvas.github.io/
RadiAnt: https://www.radiantviewer.com/
DiCoogle: http://www.dicoogle.com/
Oviyam: http://oviyam.raster.in/
Osirix: https://www.osirix-viewer.com/
RAD-AID: https://www.rad-aid.org/
