GE Healthcare The Challenge of Clinical Web Accessibility Hagay Lupesko, Software Engineering Manager, Cardiovascular IT EXECUTIVE SUMMARY Providing quality cardiovascular care is a 24/7 process. Cardiologists require quick and easy access to patient data and images in order to provide rapid and well-informed clinical decisions. As cardiologists are becoming increasingly mobile, the ability to access required patient clinical images and the access to relevant analysis tools over the Web is paramount to providing the proper level of care. Traditionally, cardiovascular PACS solutions have been a limiting factor in providing the desired level of access as remote access was usually restricted to non-diagnostic quality images and lacked advanced analysis measurement tools needed by cardiologists.
Delivering a web accessible clinical cardiovascular PACS system to meet the needs of cardiologists who demand diagnostic quality image access agnostic to their location presents a number of technological and design challenges. This technical white paper presents a full overview of the technological capabilities offered by GE s Centricity Cardio Imaging and how it addresses these challenges to deliver true diagnostic quality image access for cardiologists. CLINICAL USE CHALLENGES In today s cardiovascular PACS environment, remote clinical access has proven to be a challenge for clinicians and IT staff alike. Today s remote access solutions are typically based on a de-featured Web solution that doesn t provide diagnostic quality imaging (noncompressed images) and does not feature any measurement or analysis tools. In other words, the diagnostic image quality, and full suite of measurement tools that the physician normally has at their disposal in a cardiology reading room or a cath lab control room, is not available remotely. The fully-functional solution is strictly limited to those physical locations, forcing the cardiologist to have to travel from room to room or facility to facility to obtain the level of clinical information about the patient that is required to drive diagnosis and treatment decisions. When you consider that cardiologists and cardiovascular clinicians operate in a fast-paced, 24/7 environment, the need to access patient images and data around the clock from various locations is crucial in providing the most informed care of their patients in a timely manner. Today, for example, a cardiologist treating an acute Myocardial Infarction (MI) patient in the cath lab who wants to consult with a colleague to determine the best course of treatment, is really limited by the need to have their colleague physically present in the same room with them, looking at the same workstation to be able to see diagnostic quality images. The same holds true for an echo exam performed by a cardiovascular clinician at a distant facility; the cardiologist is unable to read the exam, perform measurements and share results and next steps until they physically travel to that facility to read the study. This increases the time it takes the cardiologist to make clinical decisions and diagnoses, time that is extremely valuable within a critical care setting. This reduced productivity can be detrimental to the quality of care that clinicians would like to provide their patients, impacting the cardiologist s daily workflow, priorities and their work-life balance. Finally, as you look at the current implementations of cardiovascular PACS systems, it is often the case that a single hospital will have multiple silos of patient images and data residing in disparate IT systems. Typically, advanced analysis software resides on dedicated workstations that must be managed separately from the cardiovascular PACS system. This means that if a cardiologist needs to perform a 3D left ventricular echo measurement after the case, they must walk over to an advanced post-processing workstation, load the study through CD/DVD media and then perform the needed analysis and measurements. This data is saved locally and on a CD/ DVD that cannot be easily added into other systems or reporting solutions. Cardiologists then have to manually input their key findings into other systems to a have a complete patient record. Such an environment not only impacts the user experience and productivity of the cardiologist, it also introduces a lot of financial burdens on the hospital by having to manage, maintain and support multiple systems and multiple archives. TECHNICAL CHALLENGES Designing and implementing a Web-accessible clinical system poses a few significant technical challenges. In this section we detail these challenges. Network Connectivity Working with a Web-accessible system implies remote users are using the network either Internet or Intranet to have their client devices communicate with the backend system. Network connectivity varies in different aspects: Bandwidth, Latency, Access Technology (WiFi, Cable, Mobile, etc.) and more. Each of these aspects affects the application in use by limiting data transfer throughput, data availability, application responsiveness and more. This eventually has a significant implication on the overall user experience and system usability. Security Private networks, such as Hospital Intranet, are usually protected by several access control means, most notably the Firewall. A Firewall controls and restricts access between networks such as the Internet and Hospital Intranet. This poses a connectivity challenge to a Webbased system it must tunnel through organization firewalls so that remote client and server communication can flow through for both inbound and outbound communications. On the other hand, a system that is accessible over the Web must stick to the highest security standards so that it is immune to Web threats such as XSS (Cross Site Scripting) or SQL Injection, protects the sensitive clinical data it stores and cannot be used to maliciously access clinical data stored elsewhere in the hospital s private network. Data Integrity In a Web-accessible system, data travels through the Web between server and clients. As data travels it is split, routed and could potentially be corrupted or even lost. The Web-accessible system must be designed so that the system can assure the integrity of received data: it must be complete, current and correct. Performance When functionality and content are accessed over the Web, network properties most notably bandwidth, latency and packet loss can potentially create a significant bottleneck that limits data throughput and system responsiveness and thus limits the client performance and user experience. 2
Centricity * Cardio Imaging Enabling Clinical Web Accessibility
CENTRICITY CARDIO IMAGING TECHNOLOGY Functionality at a Glance Centricity Cardio Imaging provides primary diagnostic image review and analysis along with advanced image display and measurement tools. The client allows easy access from practically anywhere utilizing the web as the transport channel. The Centricity Cardio Imaging client offers a highly customizable user interface, preserving the same user experience regardless of where the user chooses to access their patients images from. Built on GE s Vendor Neutral Centricity Enterprise Archive server platform, Centricity Cardio Imaging helps manage the short-term storage and long-term archiving of multi-modality images and other relevant data objects such as ECG waveforms and reports. With seamless connectivity to GE s Cardiovascular Information Systems (CVIS), Centricity Cardio Imaging accelerates clinical workflow and helps improve the physician reporting experience. High Level System Architecture Centricity Cardio Imaging is architected as a client-server system. The Backend is architected as an N-Tier Web System, exposing REST APIs accessible over HTTP or HTTPS. The Front-end is designed as a smart client supporting the Windows family of desktop operating systems, exposing generic APIs for CVIS systems as well as Advanced Analysis plugins to enable easy and seamless functionality extensions of the system. The design exhibits architectural best practices: N-Tier, SOA (Service Oriented Architecture) and strict decoupling between the various tiers. The main components, as depicted in the diagram below, includes: Smart Client, Web Server, Application Server, Databases (Management database is strictly decoupled from Images database), Streaming Server and Archive Server (Enterprise Archive). App Server Node Win Server 2008 x 64 Archive Node(s) - Multiple Nodes supported Win Server 2008 x 64 Management DB (Centricity* Cardio Imaging) SQL Server 2008 R2 x 64 NAS/SAN Storage Node(s) Imaging DB (Centricity Enterprise Archive) SQL Server 2008 R2 x 64 A Server (Centricity Cardio Imaging) Archive Server (Centricity Enterprise Archive) Web Server (Apache Tomcat) (Centricity Cardio Imaging) Streaming Server (Centricity Cardio Imaging) HTTP(S) communications HTTP(S) communications Org Firewall HTTP(S) communications Client Node WinXP / 7 x 86 / 7 x 64 CVIS API Smart Client (Centricity Cardio Imaging) Advanced Analysis Plugin API CVIS Clients Centricity Cardio Workflow, DMS,... Advanced Analysis Plugins TomTec, EchoPAC,... Centricity Cardio Imaging High Level System Architecture 4
OVERCOMING THE WEB ACCESSIBILITY CHALLENGES Web-Friendly Interfaces and Protocols Enabling system accessibility from any Internet or Intranet connected PC requires strict usage of standard Web protocols which are in common use by widespread internet applications. Utilizing a commonly used protocol ensures that Centricity Cardio Imaging communications are handled gracefully by the various network devices that run the internet: Routers, Switches, Firewalls, etc. Centricity Cardio Imaging executes all client-server communications over the de-facto internet communications protocol standard HTTP (Hyper Text Transfer Protocol). HTTP is an application-layer protocol, using TCP as the transport-layer protocol, and was originally designed to enable client and server to exchange hypertext documents. Centricity Cardio Imaging leverages HTTP to encapsulate and exchange much more than mere HTML: all client-server communications, from application control event signaling and up to sensitive image and pixel data exchange, are encapsulated and communicated using HTTP. This enables Centricity Cardio Imaging to maintain Web accessibility from practically any internet connected PC. Security is a key property of Centricity Cardio Imaging communications, and it is covered in depth in the sections below. Image Streaming Enabling physicians to access and review medical images from any Web-connected Windows-based PC client is a key and basic feature of Centricity Cardio Imaging. It is achieved through Image Streaming. Centricity Cardio Imaging s Image Streaming is essentially a mechanism that transfers the medical images from server-side image archive to the client while retaining data integrity, optimizing throughput and user experience and successfully tunneling through various network and internet devices. Considering on one hand the significant size of an average imaging study (an average Cath Angiography exam can be as large as 1 GB) and on the other hand the clinical user expectation to have cine loop loaded and playing within a few seconds - providing an adequate user experience in the face of challenging network connections is a significant challenge. In this section we explain and illustrate how this complex mechanism is designed and how the challenges are overcome. Streaming Architecture Centricity Cardio Imaging Streaming architecture implements the classic client-server model. A streaming Server software component is deployed on every Centricity Cardio Imaging Enterprise Archive node, thus minimizing DICOM files access time and read latency. Each image archive node is assigned a dedicated Streaming Server to improve overall system scalability and optimize I/O latencies. Streaming Client software component is an integral part of any Centricity Cardio Imaging Viewer, running on clients connected to the Centricity Cardio Imaging Server. All client-server communications are encapsulated in HTTP-based communications, thus enabling the image streaming to successfully tunnel through internet and intranet devices such as routers and firewalls. Secured communication is supported via the standard TLS protocol (Transport Layer Security) which effectively encrypts all image data traveling from server to client. Network Sensing Being a Web-accessible system, clients might connect to the server over a variety of connections. Some physicians might log-in from the Cath or Echo labs within the hospital, connected over a high-speed Giga-bit LAN. Others might log-in from their clinic or home, connected over a slower connection, typically a Cable Modem or a DSL connection. To optimize user experience and reduce the time it takes for the Centricity Cardio Imaging Viewer to display images and play Cine loops, the Streaming mechanism applies Network Sensing. Applying Network Sensing allows the Centricity Cardio Imaging Streaming to identify network constraints for any given connected client-server channel, and invoke the optimal Streaming Mode that will deliver an optimal user experience for the specific session. The Network Sensing mechanism is smart enough to sense multiple data sources accessed from the same client, as well as to identify changes in bandwidth in case a client s network constraints are changed. Streaming Modes Once client connection network constraints are identified by the Network Sensing mechanism, the system deduces the Streaming Mode to apply for the specific session. Depending on network constraints (primarily bandwidth) and details of the requested image set (primarily DICOM pixel data encoding) a Streaming Mode is chosen. The idea is simple and effective: for a highly constrained connection the system applies complex and custom wavelet-based compression algorithms. This enables faster transfer of image data to the client and thus reducing the waiting time experienced by the user waiting for the images to be rendered. For a fast and stable connection the system is investing minimal effort in image encoding/decoding, and the primary focus is reading image data and transferring it to the client while reducing overheads, again optimizing viewing experience to the user. 5
Progressive Quality Streaming In cases of a highly constrained connection to the server, typically when the Centricity Cardio Imaging client is used outside of the hospital s Intranet, Progressive Quality Streaming mode is activated. In this mode the Streaming Server encodes the image pixel data using GE proprietary wavelet-based algorithms. These proprietary algorithms are optimized for medical images, are unique to the GE offering, and are protected by patent law. The algorithms encode the data into size-progressing quality layers; initially the lower quality and smaller sized layers are streamed to the client so that images are transferred and rendered as fast as possible thus optimizing user experience. Following are transfers of data bits enabling the client to render a progressively increasing image quality. Centricity Cardio Imaging user can see the quality indicator labeled on the image viewport clearly, so that clinical decision making is performed on full fidelity images, as illustrated in the figure below. Smart Cine Play In Cardiovascular imaging, playing cardiac cine loops is a key system functionality. Considering the potentially constrained server connection, as well as the relatively large data size and cine frequency (up to 60 frames per second), providing an adequate user experience of minimal waiting time is a significant challenge. Smart Cine Play overcomes this challenge. Centricity Cardio Imaging Viewer considers the cine effective streaming rate, as well as other relevant parameters, and applies an optimization which allows cine to start playing even before the entire loop data was transferred to the client. This optimizes the user experience by reducing the time the user is waiting for the loop to start playing. Pre-Emptive Stream Prioritization Engine An imaging study usually contains many different image series, each containing multiple image frames and representing a different clinical view acquired during the study acquisition. As the system is streaming frames at a given pre-configured order (usually from latest to oldest), it is possible that the series most clinically-interesting to the user is actually very close to the end of the streaming queue, thus forcing the user to wait until all of the preceding images are streamed. The Pre-Emptive Prioritization Engine was designed to address this challenge; initially all representative frames for all of the series are streamed to the client, providing an overview of the available images within the Centricity Cardio Imaging Viewer Navigator window. Subsequently, the system begins streaming all frames according to a preconfigured order. However, when the user chooses to skip to another image, the system automatically preempts the streaming priority queue and immediately prioritizes the selected image to be top priority. This enables the user experience to be optimized and user waiting time for images to be reduced. Progressive Quality 6
ENABLING WEB ACCESSIBLE ADVANCED ANALYSIS TOOLS A significant part of Centricity Cardio Imaging offering is the availability of Advanced Analysis Tools for Echo, NIPV and Cath interfaced with advanced applications such as TomTec, Medis QAngio and GE s EchoPAC. Traditionally, these advanced applications are available only on a dedicated workstation, and lack the ability to easily connect to the enterprise DICOM archive. Some even require a dedicated server for tasks such as DICOM storage and license management. Centricity Cardio Imaging is designed to offer the advanced analysis capabilities offered by these applications while maintaining ease of use and retaining the flexibility of its Web-accessible architecture. Seamless Deployment and Upgrade Centricity Cardio Imaging client s seamless deployment and upgrade infrastructure automatically manages advanced application deployment on clients connected to Centricity Cardio Imaging server. For logged-in users that have the privilege to run one of the advanced analysis tools, Centricity Cardio Imaging client identifies and detects missing advanced analysis software packages or packages that require an upgrade. The user is notified and prompted for approval and the system transfers the software packages over HTTP thus ensuring successful transfer over both internet and intranet and deploys or upgrades the packages locally. No manual download or configuration is required from the user beyond an approval to install or upgrade. The figure below shows Centricity Cardio Imaging pop-up suggesting an upgrade of Echo advanced analysis tool. Centralized push deployment is also supported by providing Enterprise IT friendly Centricity Cardio Imaging deployment packages that can be easily deployed on enterprise endpoints via systems such as Microsoft System Center. Enterprise Archive Connectivity All imaging data available within the Centricity Cardio Imaging system is made seamlessly available to Centricity Cardio Imaging s advanced analysis tools. The images are streamed seamlessly from the source Enterprise Archive to the client advanced analysis tool, using Centricity Cardio Imaging Streaming components (described in detail within this paper). Moreover, advanced analysis results such as Structured Reports (DICOM SR) or Secondary Capture (DICOM SC) are all stored to the original archive and stored into the original DICOM Study, thus becoming available for future reads. Again, Centricity Cardio Imaging utilizes HTTP and TLS for storing the data, thus enabling successful communications from virtually any network-connected PC over both internet and intranet. 7
SECURING ACCESS AND USAGE As mentioned above, all of Centricity Cardio Imaging client-server communications are tunneled through HTTP. On top of HTTP, Centricity Cardio Imaging supports the secured flavor HTTPS for customers that are interested in a secured remote access to the backend. HTTPS is in fact HTTP layered on top of TLS (Transport Layer Security). TLS is a widely used internet standard protocol, which utilizes cryptographic means to enable secured communications over the internet. TLS uses asymmetric cryptography for key exchange, symmetric encryption to enable confidentiality of the data in travel and MAC (Message Authentication Code) for message integrity. To configure TLS in Centricity Cardio Imaging, the customer is required to acquire a Digital Certificate from a Certificate Authority (CA) and configure the certificate on Centricity Cardio Imaging server. This certificate is issued to the customer itself (and not to GE), and is used to identify the unique identity of the customer organization. Once the certificate is configured on the Centricity Cardio Imaging system it is used to ensure the Centricity Cardio Imaging Server identity by endpoints establishing connections, as well as to enable the encryption and message authentication of all communications between Centricity Cardio Imaging client and server. The illustration below shows secured access indicators within Centricity Cardio Imaging Login screen. SECURING PROTECTED HEALTH INFORMATION Protected Health Information (abbreviated PHI) refers to information about health status or provision of health care that can be linked to a specific individual. Regulations, such as US HIPAA Security Rule, regulates that Healthcare providers holding individual s PHI must secure PHI both at rest (e.g. when stored on archive) and as it flows over open networks. Protecting PHI for a Web-accessible system such as Centricity Cardio Imaging is a key security feature. Centricity Cardio Imaging user can login to the system from virtually any internet-connected PC, and the data communicated between client and server travels through the internet, exposed to malicious agents. To mitigate this security risk, Centricity Cardio Imaging offers HTTP over TLS communications. When configured, all client-server communications, from control messages up to image streaming, are utilizing TLS thus enabling data confidentiality and data integrity. TLS is described in detail in the previous section. 8
About GE Healthcare GE Healthcare provides transformational medical technologies and services that are shaping a new age of patient care. Our broad expertise in medical imaging and information technologies, medical diagnostics, patient monitoring systems, drug discovery, biopharmaceutical manufacturing technologies, performance improvement and performance solutions services help our customers to deliver better care to more people around the world at a lower cost. In addition, we partner with healthcare leaders, striving to leverage the global policy change necessary to implement a successful shift to sustainable healthcare systems. Our healthymagination vision for the future invites the world to join us on our journey as we continuously develop innovations focused on reducing costs, increasing access and improving quality around the world. Headquartered in the United Kingdom, GE Healthcare is a unit of General Electric Company (NYSE: GE). Worldwide, GE Healthcare employees are committed to serving healthcare professionals and their patients in more than 100 countries. For more information about GE Healthcare, visit our website at www.gehealthcare.com. GE Healthcare IT 540 West Northwest Highway Barrington, IL 60010 USA 2012 General Electric Company All rights reserved. General Electric Company reserves the right to make changes in specifications and features shown herein, or discontinue the product described at any time without notice or obligation. *GE, the GE Monogram, Centricity, and imagination at work are trademarks of General Electric Company. All other trademarks are property of their respective companies. Microsoft, and Windows are registered trademarks of Microsoft Corporation in the United States and/or other countries. GE Healthcare, a division of General Electric Company. DOC1257536