Medical Device Link.

Originally Published January/February 2001

Special Report

A New Look at Display Technologies

Plug-and-play flat-panel monitors designed for healthcare environments can help OEMs to condense product development cycles.

Norbert Sparrow

Flat panels, multiple-parameter displays, touch screens, and ever-smaller systems are changing the look of the operating room and fundamentally altering the way that medical information is communicated. Conversely, the unique safety and ergonomic demands of device OEMs along with accelerated product development times have influenced the R&D efforts among system suppliers, who increasingly offer plug-and-play units that integrate seamlessly into a manufacturer's product line. And while new display technologies promise to make medical devices sleeker and "smarter," such traditional technologies as single-parameter electroluminescent (EL) displays are not out of the picture, either. For select applications, they remain the component of choice.

Designing a Medical-Grade Monitor

Precisely rendering an image and ensuring that it is consistent across the varying systems on which it may be displayed is a critical feature of medical-grade monitors. "Flat panels behave very differently from cathode-ray tube (CRT) displays," says Piet Candeel, division manager of medical imaging systems at BarcoView, part of the Barco Group (Kortrijk, Belgium). "Mapping an image from a CRT to a flat panel without the appropriate corrections, as articulated in the DICOM [Digital Imaging and Communications in Medicine] standard, would result in an [inadequate] image impression."

BarcoView flat-panel displays come bundled with DICOM Optimizer software that allows the user to determine the transfer curve of the display system and to adapt it in accordance with DICOM supplement 28, the directive for viewing medical images. As a result, all of the company's flat panels are perceptually linearized, meaning that image perception is identical regardless of the characteristics of the display system and graphics controller that are being used.

It is equally important that the diagnostic information presented on a single display is uniform in every corner of the screen, adds Candeel. "The ability to calibrate the display so that the light output is exactly the same across the entire screen" is key in a medical application, he says. In CRT displays, the phosphor coating on the inside of the tube degrades over time. "This is just a law of physics," notes Candeel, and in medical imaging applications the display must have the capability to automatically compensate for that inevitable decay. To ensure the integrity of the image, BarcoView displays come equipped with circuitry that measures and adjusts the black and white levels 72 times per second, he notes, a function that is typically not available in nonmedical displays.

Building in Safety

The medical-grade flat-panel monitors developed by Planar Systems Inc. (Espoo, Finland) have been specified by OEMs such as Agilent Technologies and Datex-Ohmeda for use in their medical equipment. One reason for the displays' success with device OEMs, says business development director Dan d'Almeida, is the company's exacting effort to obtain comprehensive safety certifications. Planar's medical-grade systems typically meet or exceed relevant standards on electromagnetic compatibility, liquid ingress, and current leakage, and they also carry the CE marking. "Device makers understandably want to limit the amount of current that is floating around the healthcare environment. Accordingly, our displays comply with the most stringent current leakage requirements, and the EMI levels are far below what you would find on a desktop monitor," says d'Almeida. Documenting the safety of the constituent parts is one way in which display manufacturers facilitate the job of integrators and OEMs; adopting a systems-based approach is another.

Systemic Solutions

OEMs do not really want to be in the business of attaching touch screens or other components to their displays, says Bob Senior, European vice president of MicroTouch Systems (Methuen, MA, USA). "They are looking to outsource that and, at a very minimum, take delivery of a subassembly that they can integrate somewhere else," he says. BarcoView and Planar echo that sentiment, an approach that is driven largely by the need of device OEMs to shorten product development cycles.

"More and more medical companies are going from a 5-year design cycle to a 2- or 3-year cycle," says d'Almeida. "Time to market is so critical, and that is forcing companies to concentrate on their core competencies and to find partners who can take over other parts of the design process." Datex-Ohmeda's selection of the VitalScreen monitor from Planar Systems for use in its System 5 family of monitors, which was announced at the recent Medica trade show, is a prime example of how the supplier can help companies to achieve this objective, says d'Almeida. (See the accompanying article below.)

Plug-and-play flat panels are also a focus at BarcoView, which introduced a range of staged and calibrated display systems for radiology applications and ready-to-integrate flat-panel displays for soft-copy diagnostics at the recent annual meeting of the Radiological Society of North America in Chicago. (See the accompanying article on page 42 for more information about these products.) Regarding display systems, Mike Feinstein, BarcoView director of sales and marketing for North America, notes that, from a hardware perspective, the entire process must become cleaner, more streamlined, and better organized to simplify integration into new hospital constructions. He champions an "entire system that is contained within one unit rather than an assembly composed of several different components with a bunch of wires, cables, and other hookups."

BarcoView's acquisition strategy is tied into this vision. The firm recently acquired Metheus Corp. in Beaverton, OR, USA, a manufacturer of display controllers. "A standard off-the-shelf graphics card cannot display images at sufficiently high resolution for medical applications," says Feinstein, "so we made a strategic decision to acquire Metheus, which custom builds graphics cards for that purpose." The firm also offers an array of calibration and quality assurance tools, all of which enable BarcoView to offer customers "a complete turnkey solution," he says.

Putting More Data into a Smaller Space

If you have ever looked in the cockpit of a Boeing 777 or one of the other newer jets, you may have noticed that the 90-some traditional gauges have been replaced with a handful of large flat-panel monitors that are capable of displaying all of the required data. Multifunction units also have a soaring future in the medical environment, according to d'Almeida.

"From an ergonomic point of view, this gives you a reduction in data," he says. "Users don't have to scan several instruments, learning where and when to look." Instead, all of the data is centralized and can be viewed at a single glance. "But you also want an intelligent system," he adds, "one that doesn't overwhelm the user with information. You want it to show exception-based or critical information relevant to a particular procedure. And the next level would be some kind of advice showing up on the screen . . . for example, given this combination of events, here is the recommended response," says d'Almeida.

There are some applications, however, in which multiple data waveforms are unnecessary; in fact, they may do more harm than good. In cases where key information needs to be displayed without compromise, EL displays are ideal, ensuring strong demand for their use in certain types of products, notes d'Almeida. In particular, EL technology is preferable in "single-parameter products, where the user is looking at a single waveform and maybe a couple of numerical readouts," he says. "Studies have shown that while colour can be advantageous in many situations, the use of too much colour has the potential to confuse users by making them process more information than is really necessary." An EL display's single yellow waveform, because of its high contrast and viewing angles, is more easily readable than even the best LCDs on the market today, according to d'Almeida. Portability issues—EL displays are extremely rugged—and cost-per-treatment considerations are also driving growth in EL technology.

Touch Screens Point the Way to the Future

Because it is intuitively easy to use, touch screen technology is destined to play a major role in the medical industry, as it has in other sectors, according to Senior. "As the old equipment is being replaced, the graphical user interface is driving the use of touch screen technology," he adds. "That, coupled with the benefits offered by touch screens in allowing two or three applications to run on the same equipment, makes them a very attractive option."

D'Almeida also sees momentum in the use of touch screens among OEMs in the healthcare sector, although he notes that it is a relatively recent phenomenon. "Touch technology is a very attractive concept, but only recently have OEMs started to rewrite their codes to optimize the user interface," he says. Taking an existing application and simply enabling it to respond to touch is not enough, he maintains. "Try to pop open a Windows application using the little buttons on your task bar—it would be frustrating. A mouse is a much better tool for that," he notes. However, the "touch-centric" approach that OEMs are now developing coupled with the strides made by touch screen and flat-panel technology in general holds a great deal of promise, claims d'Almeida. "In the past, you had to squint when you were looking at a touch screen display system, whereas today, it's really difficult to tell that the monitor has a touch screen built into it since the image is so bright and readable."

Displays That Bend the Rules

What will displays look like five years from now? Size reduction and flexibility are among the driving forces that will engender a paradigm shift in industry, according to d'Almeida. "Microdisplays that can be worn on the head or integrated into a watch, which offer similar or better raw performance than current desktop monitor displays, will take mobility to the next level," he says. For example, Vista Medical Technologies has developed a head-mounted display called CardioView that provides data about patient vital signs as well as real-time ultrasound images to cardiologists during minimally invasive cardiac surgery. A related product, the Nomad retinal scanning display developed by Microvision, is a tiny projector that fits over the retina and enables physicians to superimpose magnetic resonance imaging scans and vital signs onto their field of vision.

Also within the next few years, you can expect to see displays with much greater flexibility . . . literally. "Displays will cease to be this rigid piece of glass with certain mechanical characteristics," says d'Almeida. "Not only will they be molded into ergonomic packages, but you will be able to fold them up when you're not using them."

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