Health care facilities can benefit from advanced network solutions that distribute, process, display, and store medical imaging data in real time using the economic and highly scalable Ethernet.
Almost every modality used in today?s modern medical facilities?including MRI, CT, ultrasound, and digital radiology (DR)?has begun to incorporate some form of real-time digital imaging.
This imaging method, where patient scans are transported in real time to PC workstations for display, processing, and storage, is redefining how physicians perform complex surgeries and diagnose life-threatening diseases, greatly improving the standard of patient care.
In the operating room, physicians are using live, high-resolution video of patients from intraoperative imaging modalities to enhance the precision of procedures like implant positioning, tumor removal, and angioplasty. The state-of-the-art vision sensors in these systems?essentially technological ?eyes??give surgeons and others visibility into parts of the anatomy they might otherwise not ?see,? allowing them to make surgical decisions that minimize damage to healthy tissue, improve results, and speed recovery.
A small-footprint, GigE Vision-compliant IP engine in the C-arm converts x-ray images to IP packets for reliable, real-time transport over a standard GigE network. A GigE network switch multicasts the imaging data to a PC for control and storage, to a software-based video processing PC for error correction, and to a display in the control room. The processing PC sends the corrected image stream back through the network to the display in the control room for multiwindow viewing, as well as to the three displays in the operating room, all in real time with low, consistent latency. All four displays are equipped with vDisplays, compact video receiver boards that convert the GigE Vision imaging stream to HDMI/DVI signals for viewing on high-definition monitors.
In diagnostic systems, real-time imaging is improving clinical assessments, reducing the need for surgical intervention in the first place. The latest DR systems, for example, are equipped with flat panel detectors that deliver uniform high-resolution images across the entire rectangular field of view. The images are streamed live to PCs for on-the-spot capture, display, and storage. The images are not always analyzed in real time, but the fast, reliable transfer of the data eliminates the wait times and costs associated with film and improves patient throughput.
Millions of Pixels
The advanced capabilities of high-resolution, real-time medical imaging systems create a huge opportunity, but also a significant challenge. Behind the crisp, high-definition images are millions of pixels of high-speed data, which must be transported, displayed, processed, and stored instantaneously with ultra-high reliability.
In today?s systems, most of the real-time functionality is achieved using point-to-point connections between a vision sensor in the modality and an image capture board in a PC, usually using specialized fiber cabling. The images often need to be viewed on more than one display in the operating room, or by staff in a control room, observation room, or training area. This is accomplished by configuring additional point-to-point connections using PCs, graphic extension boards, display controllers, and other pieces of specialized hardware.
These point-to-point connections are not only costly, they are complex, difficult to manage, and expensive to scale. Moreover, as sensors evolve to higher resolutions and faster frame rates, it will be increasingly difficult for these links to deliver the bandwidth needed for real-time image delivery.
Real-time Image Networking
The outstanding results of advanced surgical and diagnostic procedures that leverage imaging systems are creating a groundswell of demand for access among the population at large. At the same time, the ?Baby Boomers? are entering their twilight years, putting even more pressure on the health care community to make these procedures widely available. Lowering the cost of real-time medical imaging systems and finding new efficiencies in the way they are delivered are thus becoming paramount.
One of the most significant improvements that can be made to drive down costs and improve clinical workflow is to deploy a networked video connectivity system that brings together all the image sensors, PCs, processing units, and displays into a common and seamless framework. This network would complement and interface with picture archiving and communication systems (PACS) based on the Digital Imaging and Communications in Medicine (DICOM) standard.
By having all the elements connected to a network and speaking the same language, multiple streams of video from different types of image sensors can be transmitted easily to any combination of PCs, processing units, and displays. This approach simplifies the implementation of advanced multistream applications, and substantially reduces the need for costly specialized equipment and custom cabling.
Images obtained during surgery, for example, could be combined more easily than today with high-resolution 3D scans of a patient acquired before surgery. Or the sensor feeds from multiple modalities, such as intraoperative MRI and CT scans, could be more easily fused to provide surgeons with in-depth, real-time views of a region of interest. Networked topologies also scale seamlessly to accommodate increasing bandwidth requirements and the addition of new modalities, processing nodes, and viewing stations, without sacrificing existing equipment.
In addition to networking, a modern medical video connectivity solution must also offer robust, reliable transport that can deliver imaging data in real time with virtually no delay between what the sensor sees and what is projected on displays. In image-guided surgery, where a patient?s life may be on the line, not even one-tenth of a second of delay can be tolerated. And finally, to ensure interoperability and cost-effectiveness, the system must be based on mature, widely adopted standards.
This arm-type CT scanner for the head and teeth manufactured by Asahi Roentgen of Japan uses high-performance Gigabit Ethernet IP engines to stream data to a PC.
Enter Ethernet
Only one technology today meets every one of these requirements: Ethernet?the world?s lowest cost, most ubiquitous transport platform. Ethernet is a time-honored standard that is deployed in most of the world?s local area networks, including those for high-performance, real-time military and industrial applications. Ethernet is also used widely in metro transport facilities and long-haul backbone network links. It is supported by a well-understood infrastructure based on mass-produced, low-cost chip sets, switches, and cabling.
Other digital video transport protocols such as Camera Link? meet some of the above requirements, but fall short in specific areas and do not offer networking capability. Camera Link, for example, transports imaging data at high rates?up to 6.8 gigabits per second (Gb/s)?but streaming is done over point-to-point copper links of 10 meters or less, tethering cameras to PCs and image capture boards and restricting system design options. And Camera Link cannot scale to accommodate higher bandwidths.
Ethernet, on the other hand, offers exceptional networking flexibility, supporting almost every conceivable connectivity configuration, including point-to-point, point-to-multipoint, multipoint to multipoint, and multichannel aggregation. It delivers high bandwidth. Gigabit Ethernet (GigE), the widely available third generation of the standard, delivers 1 Gb/s. The fourth generation, 10 GigE, now ramping quickly in mainstream markets, delivers 10 Gb/s. All Ethernet generations use the same frame format, ensuring backward compatibility and permitting system upgrades without sacrificing the equipment already in place.
Ethernet offers long reach, allowing spans of up to 100 meters between network nodes over standard, low-cost Cat 5/6 copper cabling, and much greater distances with switches or fiber. And finally, Ethernet offers superior scalability, supporting meshed network configurations that easily accommodate different data rates and the addition of new processing nodes, displays, and switches.
GigE Vision
The benefits of Ethernet for high-performance imaging were first recognized in the industrial imaging sector about 10 years ago, when GigE was coming on stream. The popularity of GigE for industrial vision applications led to the introduction by the Automated Imaging Association in 2006 of GigE Vision?, a global open standard for distributing video and control data over Ethernet networks.
Today, dozens of leading hardware and software vendors offer GigE Vision-compliant products, and the standard is used widely in real-time imaging and video systems for medical, military, traffic control, and manufacturing applications.
Version 1.2 of GigE Vision, ratified in January, includes updates to meet growing demand for application architectures that make better use of Ethernet?s powerful networking capabilities. Past versions of the standard supported products like cameras, video IP engines, video driver software, and software development kits. Version 1.2 extends support to a rich variety of new video network elements. These include video receivers that display GigE Vision video and imaging data directly on standard displays, without the need for PCs or display controllers, as well as video servers, video processing units, management entities, and network-controlled devices.
GigE Vision allows all these network elements to interoperate seamlessly over the low-cost Ethernet platform, simplifying the design, deployment, and maintenance of imaging and video applications.
All GigE Vision-compliant products must follow the connectivity framework laid out in the standard. However, many performance-related characteristics?such as reliability and latency?are subject to the quality of the implementation. To achieve the performance required for real-time medical networking applications, it?s important to select products carefully.
Some manufacturers of x-ray equipment, MRIs, flat panel detectors, and other medical imaging systems have already begun using GigE Vision-compliant products. These products, such as small-footprint video IP engines, stream imaging data from sensors and flat panel detectors to PCs in real time for processing and display. The implementations reduce system costs by replacing expensive image capture boards with performance-oriented, GigE Vision-compliant driver software. The software runs on the GigE network interface chips/cards (NICs) built into most PCs. Economies are also found in the affordable Cat 5/6 cabling or, where regulatory requirements call for electrical isolation, in cost-effective GigE fiber connections.
The GigE Vision compliant equipment already in place in health care facilities represents an important first step in the rollout of advanced network solutions that distribute, process, display, and store medical imaging data in real time using the economic and highly scalable Ethernet infrastructure.
Video and imaging data from one modality can be multicast?sent simultaneously to multiple locations?through a switch, for example, to a processor for image correction, to a PC for storage, and to multiple video receivers for display, all in real time, with minimal amounts of specialized hardware. The long-distance reach of Ethernet allows each network element to be located where it makes sense, giving hospitals and other health care facilities more flexibility in system design than they have today.
As they evolve, real-time imaging and video networks will serve as important technology platforms for the medical community as it pushes forward into new frontiers of intraoperative surgery and diagnostic imaging. By leveraging the mainstream Ethernet networking platform, hospitals and health care facilities will be positioned to find new efficiencies in the way these advanced services are delivered, and broaden access for all.
George Chamberlain is president of Pleora Technologies in Ottawa, Ontario, Canada (www.pleora.com), a global supplier of high-performance, networked video connectivity solutions for the medical, military, and manufacturing sectors. He has been involved in the design of leading-edge communications, networking, and imaging products since the late 1980s.
