Defining Parameters: The Formula for a Great Display
In the last decade, the medical display market has seen a host of new solutions beginning with the transition from CRT systems to flat-panel monitors and, more recently, the introduction of high-resolution color display systems such as Planar’s Dome E4c, the first 4 megapixel 30-inch monitor. Remote management systems that simplify QA, calibration, and management have carved a healthy niche in the healthcare market, too.
The right diplays can boost reading efficiency and workflow, which, in turn, aids turnaround time and workflow and increases revenue. Making the right display choice hinges on understanding the subtle and not-so-subtle differences between systems and vendors. Other key concepts to contemplate include how radiology came to accept current display configurations and how display configurations will evolve in the next several years.
| Displays: A Bright Future |
| The diagnostic display market is crossing the high-resolution color threshold, and healthcare is re-evaluating its options and solutions. At the same time, the current market provides an excellent vantage point to consider the future of the display world, beginning with the near-time available solutions and progressing into newer models in much earlier stages of research and development.
The current radiology practice faces a trio of factors that play a key role in display decisions. For starters, the 21st century radiology department operates more higher resolution image capture devices than its predecessors. Optimizing the display of images captured on these devices ranks high on the priority list. What’s more, the PACS market has matured; more historical images are online and available for digital comparison. Radiologists can optimize viewing of multiple data sets and increase reading efficiency with more real estate, i.e. larger display systems. Finally, the widespread adoption of multidetector CT has fueled the 3D market. 3D has become an essential tool in many radiology departments. PACS vendors have embraced 3D and integrated 3D functionality into PACS, which changes the use of color as 3D requires color. As hospitals and imaging centers weigh these factors and consider their financial restraints, they need to re-evaluate the medical display configuration. Key questions to ask include:
Looking to the future, several factors come into play. A basic limitation that exists in the Microsoft operating system today is the fact that image data can only be pushed to the display as 8 bit images. Today the work-around for this is using window and level tools to see the full 10, 12 or 14 bits of data that were captured at the modality. One of the exciting features of the forthcoming Vista operating system is the ability to push the full image data set, up to 14 bits of data per pixel, all the way to the display and within the standard functionality of the operating system. “Vista will enable our Dome displays to be used to their full potential. Our displays today have the ability to show up to at least 1024 calibrated gray shade levels, the challenge has been getting that much data to the display given the limitations of Windows,” says Herguth. “We believe that giving the radiologist more calibrated gray shade levels will help improve efficiency by eliminating some of the window and level manipulation and hopefully provide a clinical benefit as well.” The market is muddled with claims of gray shade levels, palettes, and how many bits a display can handle. The key numbers to focus on are how many of the gray shades fall on the DICOM calibration curve and how many calibrated gray shades can be visualized by the radiologist. Peering farther into the future, Herguth says Planar will continue to adhere to its proven model: balancing physical size, pixels and cost. The company will continue to innovate and push the number of pixels. Digital mammography images, for example, reach a size of 4,093 x 3,328. The ideal diagnostic display will show digital images in full resolution in more than a single image view at a cost-effective price point. Medical display technology continues to march forward. A partnership with the right vendor can deliver numerous benefits, enabling healthcare enterprises to effectively understand, plan and budget for future solutions that promise to fill the twin objectives of the radiology department: accurate interpretation and streamlined workflow. |
Best practices: Present & future
The rapid evolution of the medical display market brings significant opportunities to improve workflow and the bottom line; however, to capitalize on the potential of new and upcoming solutions, radiology and IT departments need a thorough grounding in best practices.
One of the top issues centers on the use of off-the-shelf monitors in healthcare. Indeed, the boundary between medical and commercial monitors seems to blur by the day. At first glance, price appears to be the only difference between commercial off-the-shelf monitors and their more expensive medical-grade relatives. So how does the budget-conscious enterprise weigh its options to effectively invest in and optimize display systems?
“Medical grade is important,” confirms Jeff Shepard, PhD, medical physicist with MD Anderson Cancer Center in Houston. A medical-grade display system can be calibrated and provide an equivalent contrast perceptibility at every brightness level. There is no difference in contrast sensitivity in the very darkest and brightest regions of the display, which is necessary for accurate medical diagnoses. It is possible to purchase third-party solutions to manually calibrate commercial monitors, but manual calibration can be an imperfect and time-consuming IT labor drain. Medical-grade displays include software to maintain calibration and adjust the brightness as the backlight deteriorates, minimizing the need for manual calibration and intervention.
John Weiser, PhD, medical physicist with Qualiteering Labs LLP in Thurmont, Md., adds to the case for choosing medical-grade displays. Medical grade implies a medical grade warranty. “Radiology and medicine require a certain image quality and brightness that must be maintained over the life of the display,” explains Weiser. A medical warranty specifies a minimum brightness level over the life of the display. On the other hand, a warranty on a commercial off-the-shelf monitor typically covers nothing beyond defects in material and workmanship.
There are factors to consider in the display evaluation process beyond the medical grade label. A consulting physicist or staff imaging physicist can provide the expertise necessary to evaluate options. The key to optimal soft-copy performance is calibration. “It’s important to purchase a monitor that is self-calibrating, use the graphics card that the self-calibration is designed for and rely on software for managing calibration,” explains Shepard.
In addition, remote management technology such as Planar’s Dome Dashboard has been on the market for several years and has clearly demonstrated its merit. The technology assesses key parameters such as peak white levels, percentage driving levels and temperature. “We’ve had engineers show up in the reading room and ask radiologists to stop reading because the software detected a problem with the display before the radiologist could observe any differences,” says Shepard. Remote management not only provides quality and workflow benefits but also streamlines the budget process. Rising driving levels give the facility advance warning to budget for a replacement display.
“As sites are evaluating different display solutions, they need to look at the stability of the self-calibration software and the robustness of remote monitoring tools,” says Shepard. MD Anderson engineers assessed the stability of three vendors’ self-calibration tools by testing each at gradually increasing increments of time from every two hours to monthly. Each system was tested cold when first turned on and then 15 minutes later. Planar’s Dome display systems surpassed the site’s testing criteria.
The final factor in the evaluation process is service and support. Shepard recommends facilities meet with the engineering teams of vendors under consideration to determine their responsiveness and flexibility. “We’ve had the same vendor for five years. Planar goes out of its way to make customers happy,” concludes Shepard.
Conclusion
The right display system can make a significant difference in the practice and workflow of radiology. The ideal solution is manufactured for the medical market and includes the calibration and management software, warranties and support necessary to optimize medical image interpretation.
| Eye on Efficiency: The Ideal Display Configuration |
David S. Channin, MD, chief of imaging informatics at Northwestern University’s Feinberg School of Medicine in Chicago, is a leader in the digital image and information world. Channin’s mission is to improve the practice of radiology by providing radiologists with tools to optimize their accuracy and efficiency in the reading room. As the display market transforms itself with new choices, Channin is on the cutting edge of display research. His work entails investigating and testing various display configurations to bring radiology closer to the ideal solution. This month, Channin visits with Health Imaging & IT to discuss how radiology arrived at current display practices and consider how new options will improve the reading environment. How did two high-resolution grayscale monitors and the third color system for worklist become the default configuration for radiologists? When radiology first moved to digital display, radiologists thought they wanted to duplicate the lightbox, so we saw a lot of 1 by 4 [1 row of 4 displays] setups. Very quickly, people realized that they were no longer tiling cross-sectional images but rather cinematically viewing stacks of images and they could manage with two displays. As people got more and more sophisticated in their use of PACS workstations they saw the need for a third display to support, for example, color images including 3D displays, worklists and other software applications that run on the workstation. Has radiology found the ideal display resolution? Or are there challenges? The issue of display resolution is complex and therefore leads to challenges and controversies. Three megapixel displays have a pixel size that is close to optimal for the human visual system at a ‘restful’ viewing distance (approximately 60 cm). Most computed radiography, direct radiography and digital mammography images have more than 3 million pixels, however, and so the image must be sub-sampled to fit on the screen. This means that the radiologist must zoom and pan the image to examine it completely at the optimal performance of the eye. With a 5 megapixel display, one may not have to zoom and pan a 3 megapixel image, but the radiologist must be closer to the display and this can be fatiguing. Zooming and panning also slow radiologists down; that’s a big problem. With cross-sectional images that are typically smaller in size, some people do use ‘off-the-shelf’ displays. One has to take into account, however, the need for high brightness and the need for extra space to display additional series of images and comparison studies. The number of series and comparison studies per case is growing, which means higher resolution displays will be more and more useful. High-resolution color display systems are beginning to make a splash in the market. Yet they represent a new paradigm for healthcare with some facilities unsure how to best optimize the new solutions. What diagnostic applications are best suited for color displays? There are many interesting things that can be done with color in addition to the display of color images and 3D renderings. Color user interface elements, overlays, decision support and reporting tools are a few examples. The second area with potential is pixel color. The eyes are more sensitive to green light, so we might use greenish pixels to improve radiologist’s ability to detect subtle features. Finally, we can use a pseudo color table to extend the shades of gray. The Dome E4c is interesting because it raises the bar for color displays. It provides a large amount of real estate, while at the same time providing high dynamic range. It may be very valuable in the display of a large number of CT or MR series of images where grayscale images are juxtaposed with color 3D renderings. What about off-the-shelf displays? Do they have a role in the reading room? Probably not. The off-the-shelf advocates rely on a flawed argument. Spatial resolution may not be a challenge with a single image stack, but radiologists are not viewing a single stack or even four stacks of images. They’re viewing multiple stacks and comparing historical studies, which means they need more and brighter pixels to perceive the shades of gray. This means DICOM calibration, which leads us right back to medical grade display systems. The FDA requires 5 megapixel grayscale monitors for digital mammography interpretation. This requirement seems to place an added burden on digital mammography sites. What does the research suggest? Whether or not the specialized mammography displays are worth the extra investment is under study. We hope to provide some answers via a National Institutes of Health (NIH) grant to compare the use of 3 megapixel color, 3 megapixel grayscale and 5 megapixel grayscale for digital mammography interpretation. Is there an ideal display system? An 80-inch, 40-megapixel color display might do it. Is this where display design is headed?I hope so. The technology to develop a 40-million-pixel system exists, but medical informatics is not going to get any help from the entertainment or gaming industry on this one. TV development is stopping at high-definition TV. So it will be very hard to reach the next stage of display design. What does this mean for medical imaging display buyers?It means that we have to be clever about our display systems. Display software has to provide more functionality integrated into the user interface to maximize use of the displays. Another strategy is to look at different combinations of color and monochrome display systems and optimize the combination by displaying the right image on the right display. Disclosure: Dr. Channin receives research and development funding from Planar. |