PACS and EdgeNexus ADC (EdgeADC) Guide

Table of contents


Medical imaging has become an irreplaceable element in modern healthcare. From digital X-rays to complex MRI scans, these technologies enable doctors to peer into the human body without making a single incision. As the demand for these images skyrockets, the systems used to store and deliver them are under increased strain. It’s crucial for healthcare providers to ensure that these systems are not just operational, but are also swift, reliable, and efficient.

Enter Edgenexus EdgeADC – a solution tailored for this very challenge. This state-of-the-art Application Delivery Controller (ADC) brings robust load balancing capabilities, ensuring that medical imaging systems are both accessible and resilient. Its sophisticated algorithms effectively distribute incoming requests to various servers, preventing any single system from getting overwhelmed. This ensures smoother user experiences for healthcare professionals and minimizes downtime, which is critical in life-saving situations.

But how do you navigate the intricacies of deploying such an advanced solution? Our guide offers a comprehensive roadmap. Whether you are an IT manager at a large hospital or a technician at a smaller clinic, this guide provides step-by-step instructions to optimize your medical imaging systems using Edgenexus EdgeADC.

Beyond the technical details, you’ll gain insights into best practices, potential challenges, and success stories from healthcare institutions around the globe. By the end of this journey, you’ll be equipped to turn your medical imaging infrastructure into a high-performing, reliable asset that meets the demands of 21st-century healthcare.

Join us as we delve into the transformative potential of load balancing in medical imaging and harness the power of Edgenexus EdgeADC to elevate patient care to unparalleled heights.

Supported Medical Imaging Systems

There are a number of medical imaging systems available on the commercial market, and almost all will use the DICOM, HL7, XDS, and XDS-1 protocols that this guide covers.

The Symphony of Medical Imaging Understanding its Core Components

Step into the world of medical imaging, and you’re stepping into a dance of technology and medicine, a symphony of intricate components working seamlessly together. Every day, millions trust these systems to unveil the hidden realms of the human body. But what makes up this technological marvel?

Imaging Modalities

At the heart of any medical imaging system is the modality – the machine responsible for capturing the image. From the iconic X-ray machines, which harness radiation to capture snapshots of our bones, to the resonant hum of Magnetic Resonance Imaging (MRI) machines, which use magnetic fields to illustrate soft tissue details, each modality serves a unique purpose. There’s also the ultrasound scanners, PET (Positron Emission Tomography),  and the CT scanner, combining multiple X-ray images to produce cross-sectional views.

Acquisition Systems

These are the unsung heroes, the backstage hands of the imaging world. They capture, amplify, and convert the raw signals into digital data. Think of them as interpreters, translating the language of radiations or waves into discernible, digital information.

Computing Workstations

Once the data is captured, it needs processing. The high-end workstations come into play here, equipped with powerful software to process and enhance these images. With cutting-edge graphics and processors, they transform raw data into the crisp, clear images doctors analyze.

Archiving Systems

Medicine thrives on history. A patient’s past scans can hold the key to diagnosis. This is where Picture Archiving and Communication Systems (PACS) come in. They store countless images in digital archives, making retrieval swift and effortless. In today’s connected age, Cloud-based PACS systems ensure these images are available anytime, anywhere.

Display Systems

Last but certainly not least are the display systems. These specialized monitors are calibrated for precision, ensuring that every pixel of an image is represented accurately. On these screens, radiologists spend hours, their trained eyes scanning for anomalies or signs of diseases.

Dive deeper into medical imaging, and you’ll discover a harmonious collaboration of technology and medicine. Each component, from the towering MRI machine to the humble processing unit, plays a crucial role in unveiling the stories beneath our skin. And in this dance, accuracy, and precision lead the way, ensuring the best possible care for patients worldwide.

PACS & VNA The Digital Memory Banks of Modern Medicine

Imagine a vast digital library, its virtual shelves filled not with books but with the intricate stories of the human body. The ability to store, access, and share medical images seamlessly has become paramount in the digital age of medicine. At this revolution’s epicenter are PACS (Picture Archiving and Communication System) and VNA (Vendor Neutral Archive). Together, they form the backbone of modern medical imaging storage and distribution.

PACS (Picture Archiving and Communication System)

Think of PACS as the central hub of a bustling airport, guiding flights (or, in this case, images) to their appropriate destinations. Born in the late 20th century, PACS transformed the world of radiology by digitizing it. Gone were the days of physical films that could be easily lost or deteriorated; in came a system that could easily store countless digital images. Beyond mere storage, PACS revolutionized image retrieval and distribution, making it possible for a doctor in one wing of a hospital to access an X-ray taken in another instantly. This breakthrough system ensures that no matter where a patient’s journey might take them within a healthcare facility, their medical images are always just a click away.

VNA (Vendor Neutral Archive)

If PACS is the airport hub, VNA is the universal adapter plug, ensuring that devices of all makes and models can connect seamlessly. As medical imaging diversified, introducing a myriad of devices and formats, there arose a need for a system that could store images in a standardized manner. Enter VNA. It’s “vendor-neutral” in the truest sense, allowing images from different imaging devices, regardless of their manufacturer, to be stored and accessed cohesively. This ensures that doctors don’t get bogged down by technical disparities, and can instead focus on what truly matters patient care.

The journey of medical imaging, from capture to diagnosis, is a complex ballet of technology. With PACS and VNA at the helm, this dance is perfectly orchestrated. They ensure that each image, each slice of a patient’s story, is stored with the respect and care it deserves, ready to be recalled at a moment’s notice. As medicine continues its march into the future, these systems stand as a testament to the wonders of technological innovation, working silently in the background to make healthcare more efficient, connected, and holistic.

Linking to administration systems

It’s not just the medical imaging systems that are critical to a hospital’s efficient running. There are also a number of important that the hospital staff utilize on a 365/24/7 basis that are inextricably linked to the imaging technologies in place. These include the following

ADT – Admission, Discharge and Transfer System 

Picture a grand choreographer, overseeing the intricate dance of patients as they journey through a healthcare facility; that’s the Admission, Discharge, and Transfer System (ADT) in essence. With an eagle’s eye, ADT tracks every patient’s movement, from the moment they step into the facility for admission, to their eventual discharge, and even transfers in between departments or facilities. It ensures beds are allocated efficiently, patient records are updated in real time, and the transition from one phase of care to another is smooth. ADT is the silent sentinel, ensuring that every patient’s journey is seamless, organised, and well-documented in the bustling world of healthcare.

PAS – Patient Administration System 

At the heart of patient-centric healthcare lies the Patient Administration System (PAS). This dynamic system acts as the operational backbone, ensuring that the logistical side of patient care – appointments, registrations, bed allocations, and billing – operates with clockwork precision. PAS is like the friendly receptionist who remembers every patient’s appointment, the meticulous accountant who keeps track of every bill, and the compassionate caregiver who ensures that every patient finds their way. It bridges medical and administrative tasks, ensuring patients can focus on healing while the system takes care of the rest.

HIS – Hospital Information System 

Step inside the digital nervous system of a modern healthcare facility, and you’ll find the Hospital Information System (HIS) pulsating at its core. A powerhouse of integration, the HIS seamlessly collates every fragment of hospital data, from patient histories to billing details. It’s the digital conductor orchestrating a symphony of processes, ensuring that hospital operations flow with clinical precision. Whether it’s scheduling patient appointments, managing the inventory of critical medicines, or even overseeing the hospital’s financial ecosystem, the HIS is the unsung hero, working tirelessly behind the scenes to make healthcare efficient, holistic, and patient-centric.

RIS – Radiology Information System 

Venture into the world of radiology, where images tell stories, and you’ll discover the Radiology Information System (RIS) – the guardian of these tales. Acting as the brain behind every radiology department, RIS manages everything from patient scheduling to image storage, from report generation to workflow management. It’s like a skilled librarian who knows where every X-ray, MRI, or CT scan is stored, ensuring that radiologists can access the needed images swiftly. More than just storage, RIS simplifies complex radiology workflows, streamlining patient care, and ensuring that each image is matched, tracked, and delivered to its rightful place in a patient’s narrative.

Peripheral Equipment

Alongside the scanners and imaging systems, it is essential for clinicians and radiographers to have the ability to view the imagery in precise detail. To achieve this goal, clinicians and radiographers are provided with Dicom Workstations and Viewers.

Dicom Workstations 

Enter the control room of modern radiology, and you’ll encounter the Dicom Workstation. It’s more than just a computer; it’s a specialized hub tailored to manage the intricacies of medical imaging. Picture a maestro orchestrating a multi-instrument symphony, and you capture the essence of this workstation. Within its digital confines, radiologists can process, analyze, and manipulate medical images with unparalleled precision. Thanks to its specialized software and high-resolution display, even the minutest detail in an MRI or CT scan doesn’t go unnoticed. Whether it’s pinpointing a hairline fracture or tracing the contours of a cardiac artery, the Dicom Workstation ensures that healthcare professionals have the most advanced tools at their fingertips.

Dicom Viewers

Imagine a magnifying glass, capable not only of enlarging but of illuminating the very soul of a medical image. That’s the Dicom Viewer for you. A sophisticated software application, the Dicom Viewer is the window through which doctors gaze into the myriad tales told by medical images. With a suite of tools allowing for zooming, panning, adjusting brightness and contrast, and even annotating, it transforms raw images into narratives. Whether it’s a surgeon preparing for a complex procedure, a radiologist interpreting a scan, or a physician seeking a clearer view of an ailment, the Dicom Viewer brings these images to life, ensuring that each diagnosis is backed by crystal-clear visual evidence. It’s not just a viewer; it’s the lens that brings clarity to medical imaging.

Dicom or Not? – That is the Question

The DICOM Protocol

DICOM, or Digital Imaging and Communications in Medicine, is a global standard for storing, sharing, and transmitting medical images, ensuring consistent and seamless communication across different healthcare devices and systems. It’s the lingua franca of medical imaging, allowing devices like MRIs, CT scanners, and ultrasounds to speak the same digital language.

The Edgenexus EdgeADC has a specifically authored Dicom load balancing schema that ensures that all Dicom traffic is handled by a highly tuned engine. To further achieve the most efficient load balancing possible, Edgenexus, in conjunction with one of the leading suppliers of Dicom based imaging systems.

Non-Dicom Protocols

Below are just a few of the non-DICOM protocols that are used in medical imaging. The choice of protocol will depend on the specific needs of the application. For example, JPEG may be a good choice for images that need to be stored or transmitted over a limited bandwidth, while MPEG may be a better choice for images that need to be played back in real time.

  • JPEG This is a lossy compression standard that is commonly used for medical images. It can achieve high compression ratios without sacrificing too much image quality.
  • MPEG This is a family of lossy and lossless compression standards commonly used for medical images. MPEG-2 and MPEG-4 are particularly well-suited for medical imaging because they support high compression ratios and high frame rates.
  • TIFF This lossless compression standard is sometimes used for medical images. It is not as widely used as JPEG or MPEG, but it can be a good choice for images that require high image quality.
  • HL7 This messaging standard is used for exchanging clinical data between different healthcare systems. It can also be used to exchange medical images but is not as commonly used as DICOM.
  • WADO-RS This is a RESTful web service standard for exchanging medical images online. It is a newer standard than DICOM, but it is gaining popularity because it is more flexible and scalable.

It is important to note that DICOM is still the most widely used protocol for medical imaging. It is supported by a wide range of imaging devices and software applications and offers several essential features for clinical workflow. However, the non-DICOM protocols listed above can be a good choice for applications where DICOM is not a good fit.

Reasoning Behind Load Balancing Medical Imaging Systems

Medical imaging systems are critical components in healthcare delivery. As the demand for imaging services grows, so does the load on the imaging servers, storage systems, and network infrastructure. Load balancing, in this context, refers to distributing incoming digital imaging requests across multiple servers or resources. This is vital for ensuring that no single system or resource becomes a bottleneck, which could potentially hamper the delivery of imaging services.

Benefits of Load Balancing Medical Imaging Systems

Improved System Availability

Load balancing helps in achieving higher system availability by ensuring that if one server or resource fails, the incoming requests can be directed to another functioning server. This redundancy reduces system downtimes and ensures uninterrupted access to vital imaging data.

Enhanced Performance

Distributing the load means that no single server is overwhelmed with requests. As a result, each server can operate optimally without being overloaded, leading to faster response times for accessing and viewing medical images.


As the demands on an imaging system grow, additional servers or resources can be added to the load balancing configuration. This modularity ensures that the infrastructure can scale in response to increasing workloads without a complete overhaul.

Optimal Resource Utilization

Load balancing ensures that all servers in the configuration share the workload, preventing any single server from being underutilized or overburdened. This leads to more efficient use of the available resources, optimizing the investment in hardware and infrastructure.

Reduced Latency

By directing requests to the most appropriate or nearest server, load balancing can reduce the time taken to fetch an image. This is especially important in emergency scenarios where every second count.

Failover Protection

Load balancers can detect a malfunctioning server and redirect requests to other operational servers. This failover capability ensures that the overall imaging service remains available even if a part of the system encounters an issue.

Flexibility in Maintenance

With load balancing, maintenance tasks such as updates or repairs can be performed on one server while others remain operational. This means that routine maintenance doesn’t disrupt the availability of imaging services.

Enhanced User Experience

For end-users, like radiologists or clinicians, load balancing means faster image retrieval, uninterrupted access, and a more reliable system. This improves their overall experience and enables them to provide timely and efficient patient care.

Fault Tolerance with PACS Systems Using EdgeADC

In the digital realm of modern healthcare, Picture Archiving and Communication Systems (PACS) stand as pillars of innovation. These systems house the intricate web of medical images, ensuring they’re accessible whenever and wherever needed. But what happens when unforeseen challenges threaten this accessibility? Enter fault tolerance, particularly with the integration of the EdgeADC.

Understanding Fault Tolerance

At its core, fault tolerance is about resilience. It’s the ability of a system to function smoothly, even when parts of it encounter issues. For PACS, this means ensuring that medical imaging data remains accessible, even if some servers or network components fail.

The EdgeADC’s Role in Enhancing Fault Tolerance

The EdgeADC is not just a tool; it’s an armor for PACS. Designed to optimize and secure application delivery, it plays a crucial role in elevating the fault tolerance of PACS systems.

Load Balancing Prowess

One of the EdgeADC’s standout features is its load balancing capability. By distributing incoming PACS data requests across multiple servers, The EdgeADC ensures that no single server bears the brunt. This distribution not only enhances system performance but also acts as a safeguard. If one server fails, requests are seamlessly redirected to operational ones, ensuring uninterrupted access to vital imaging data.

Health Monitoring

The EdgeADC is continually on the lookout. Its health monitoring features are akin to a vigilant sentinel, regularly checking the health and performance of servers. If it detects an anomaly or a server’s potential failure, it preemptively reroutes requests, ensuring service continuity.

Persistent Sessions

In the world of medical imaging, data integrity and continuity are paramount. The EdgeADC’s persistence features guarantee that user sessions, once initiated, are maintained even if a specific path within the system encounters issues. This means uninterrupted access to imaging data for radiologists, even amidst backend challenges.

Global Server Load Balancing (GSLB)

With the rise of multi-site PACS configurations, the need for global load balancing has become apparent. The EdgeADC’s GSLB functionality ensures that even if an entire data center faces issues, user requests can be directed to another operational data center, maintaining the PACS system’s availability on a global scale.

SSL Offloading

Security is a cornerstone in healthcare. The EdgeADC offers SSL offloading, relieving PACS servers from the intensive task of encrypting and decrypting user sessions. This enhances server performance and adds a layer of resilience against potential security threats.

Data Compression and Acceleration

For fault tolerance, speed is of the essence. The EdgeADC’s ability to compress data and accelerate content delivery ensures that even in sub-optimal conditions, PACS images are delivered promptly and efficiently.

Load Balancing & Service Types for PACS

Load balancing is crucial for PACS (Picture Archiving and Communication Systems) due to the intensive nature of medical imaging data and the importance of maintaining high availability and swift access. Several methodologies can be employed to ensure effective load balancing for PACS. Here are some of the most common strategies and a detailed explanation of each

Round Robin

Perhaps the simplest of all methodologies, the Round Robin strategy distributes incoming requests in a cyclical manner. If you have three servers, the first request goes to the first server, the second request to the second server, and so on. After the last server in the list, it goes back to the first server. While it does ensure even distribution, it doesn’t take server load or health into account, which can be a limitation.

Least Connections

In this strategy, the incoming request is sent to the server with the fewest active connections. It’s predicated on the idea that a server with fewer connections is likely less busy and therefore can handle a new request more efficiently. It’s particularly useful for situations where servers have varying levels of capability and performance.

Least Response Time

This method directs traffic to the server with the quickest response time for a new connection. By constantly monitoring server response times, it ensures that requests are handled promptly, optimizing user experience.

IP List Based

An algorithm determines the server to which a request will be sent based on the IP address of the client or the receiving server. This method offers a consistent connection experience as a specific IP will always be directed to the same server, provided no changes occur in the server pool.

Weighted Load Balancing

Not all servers in a PACS system may have the same processing capability. Weighted Load Balancing considers this by assigning a weight to each server based on its processing power. Servers with higher weights receive a proportionally larger number of requests.

Persistence (or Sticky Sessions)

In some PACS operations, it’s essential for a user or session to maintain a connection with the same server, especially if the session involves multiple transactions. Persistence ensures that all requests from a particular session are directed to the same server, enhancing data consistency.

Layer 7 Load Balancing

This is a more sophisticated form of load balancing which makes routing decisions based on the content type, URL, or other HTTP header information. For PACS, this can be useful to prioritize or manage specific types of imaging data or requests differently.

Global Server Load Balancing (GSLB)

For organizations with multiple data centers or global operations, GSLB is used to distribute traffic across servers in different geographical locations. This ensures high availability and resilience in case an entire data center goes down.

Layer 7 Health Checks

An integral part of any load balancing strategy, Layer 7 health checks will not only continuously monitor the health and performance of servers, but also of direct and indirectly linked applications. If a server or application fails or is underperforming, the load balancer will stop sending it new requests until it’s operational again. This ensures high availability and system robustness.

Incorporating the right load balancing methodologies in PACS ensures that medical imaging data remains accessible and can be retrieved swiftly and efficiently, which is crucial for timely medical decisions and patient care.

Reverse Proxy or Direct Server Return?

Many load balancer, or ADC, vendors recommend that users utilize the speed associated with Direct Routing, also known as Direct Server Return. This is a situation where the traffic inbound to the servers is sent via the Reverse Proxy engine, and then traffic bound to the user is sent directly to the user client. The main reason for doing this is to bypass the Reverse Proxy as it slows down the traffic.

With Edgenexus EdgeADC, this is not a recommendation we make.

We always recommend that adminstrators use Reverse Proxy for both ingress and egress through the EdgeADC. We are confident with this statement as our Reverse Proxy is authored in-house, not open-source-based, and engineered for speed and efficiency.

Load Balancing Medical Systems – Example Architecture

Below is an example of how a complete PACS, VNA, RIS and HIS systems may be load balanced using the EdgeADC. Detailed VIP configurations vary depending on the nature of the installation and the vendor.