Sunday, December 20, 2020

Using an Open Source PACS

 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.