The Best on Display

By providing bigger and better images in recent years, the technology in medical monitors has boosted capability, both with increased accuracy and ease of use. The progress translates into more accurate diagnosis and surgery; that is, it can save lives.

Medical monitors are different from common desktop monitors in many ways. Many of them come with panels that can be cleaned for the sterile environments required of operating rooms, intensive care units (ICUs) and emergency rooms. They offer higher resolution; better color quality; greatly enhanced grayscale image quality; compliance with FDA and professional medical standards (assuring consistent imagery among monitors and associated medical equipment) and more rapid start-up. Some of these enhanced capabilities result from underlying, higher bit-depth architecture. The use of these improvements has emerged in the past five years.

“Medical approval is necessary in order to use a monitor in a hospital environment. Off-the-shelf displays don’t require that,” pointed out Lynda Domogalla, director of product marketing, Barco Medical Imaging Division. The Department of Veteran’s Affairs’ national VistA patient record program and active duty military hospitals with PACS (picture archiving and communications system) use many Barco, Planar Systems Inc. and Hewlett Packard medical monitors.

While desktop monitors utilize landscape mode with 1,600 x 1,200 pixels, medical monitors use portrait mode with 2,048 x 2,560 pixels or higher resolution. Grayscale image quality is brighter, with higher contrasts than a desktop monitor. “Medical monitors can display up to 1,024 shades of gray, whereas a standard display has less than 250 shades of gray,” said Domogalla. “This allows radiologists to see more detail in an image.”

Quality assurance in medical monitors is mandated by DICOM (digital imaging communications), an Association of Computed Radiography standard which provides guidelines to assure that an image is the same on one monitor as another. The standard also assures that all the data is included, as vital information can sometimes be subtle. “If the display were not DICOM-calibrated, you might not see some of the information that is there. Radiologists want to make sure that they can see all the information, so they can issue a good diagnosis,” said Domogalla.

If the Joint Commission on Accreditation of Healthcare Organizations pays a surprise visit, it is necessary to prove that medical monitors are in DICOM calibration. “Today’s calibration software runs every four minutes behind the scenes to make sure you are in calibration at all times,” said Kelly George, strategic national market manager, Planar Systems Inc.

“DICOM calibration changes the monitor from its native imaging to a DICOM curve which allows the eye to see the most shades of gray, as long as the monitor is always calibrated to a DICOM curve,” said George. To maintain vigilance, Planar offers the Dome Dashboard, remote monitoring calibration software now used by the Portsmouth Naval Medical Center, she said. Planar’s monitors come with Cxtra calibration software which looks at individual workstations, whereas Dashboard looks at the entire network.

Medical professionals need to see the same amount of detail on their screens as that which is captured by imaging devices such as X-rays, or CR/DR (computed radiography/digital radiography), the two ways to acquire X-rays; MRIs (magnetic resonance imaging); ultrasound; and CTs (computed tomography).

As such, medical monitor technology pays close attention to the consistent quality of the liquid crystal panel and backlight behind it, which sends light through it. “Our standard LCD monitor has 15 backlights and in front of them is a diffuser to make sure the light is even so you are not seeing 15 strips of light running up and down the screen,” said George.

Planar has improved the luminosity and contrast ratios of its medical monitors in recent years. “It’s now in the 900-cd/m2 range,” said George. The 900 number represents candellas per squared meter and the Planar medical monitor contrast ratio is 800:1. The contrast ratio works in conjunction with a PACS software tool called “Windows Leveling,” which allows a radiologist to adjust an image to blacker or whiter to see more detail.

Before the improvement of backlights, grayscale monitors produced better brightness than color monitors. But once the backlight technology improved, the use of color medical monitors grew. “The FDA requirement is 175 cd/m2 in order for a color monitor to be of diagnostic quality,” said George.

Owing to the advances in backlight technology, Planar released a new line of color diagnostic displays last year. Working with 3-D software, color medical monitors take a medical professional through the body three-dimensionally in order to see, for example, an entire tumor rather than seeing it in pieces. In addition, it is now possible to have both color and grayscale on one monitor. However, color coding, color fusion and volumetric 3-D provide more ways to differentiate for enhanced diagnostics in the brain, vascular system and orthopedics. “Volumetric 3-D means you can re-assemble 3-D images instead of seeing the images only sliced and flat, said George.

Both Barco and Planar Systems Inc. provide DICOM calibration and are approved by VISTA, the Department of Veteran’s Affairs national health care information system. Planar organizes its medical monitor offerings by increasing megapixals (MP). The Planar E3-2, with 3 MP, is used for diagnostic readings of X-rays, (CR/DR), ultrasound (sonography), MRI and CTs.

The Planar Dome E4c carries 4 MP and is used for the same as above but also in an operating room, an ICU and emergency room. The large-screen (30 inches) color monitor can show 15 full size 512 x 512 images concurrently and comes with a protective panel, allowing it to be cleaned for a sterile environment. It is FDA 510(k) cleared and medically certified.

When Microsoft’s Vista operating system is released, the bit-depth capacity of the operating system will rise from 8 bits in XP Pro to 10 bits in Vista, thereby enabling the Planar displays to show more bits.

“It didn’t matter if our acquisition of images could show 12 bits because XP Pro could only pass through 8 bits of the image,” pointed out George.

In order to reach 12 bits, driver manufacturers for video boards have developed software that enhances the bit depth of the image, George explained. But the ability to get full bit-depth capacity also depends on the PACS. “All PACS software is now 8-bit so they will have to upgrade to 10-bit to be up-to-date with Microsoft’s Vista and Planar’s monitor capability,” pointed out George. PACS software also is becoming more Web-based to enable the loading and moving of MRI images (the biggest file, larger than X-ray files), she noted.

Technology improvements in medical monitors also have eased burdens on hospital staff outside of radiology and operating rooms.

“We used to have CRTs, like regular computer monitors, which were heavy and awkward to work with. They were about 100 pounds each and the resolution wasn’t great. As soon as the flat panels came out, we got rid of them,” said Kay Wright, imaging systems manager at the VA Medical Center in Louisville, Ky.

Right out of the gate, flat panel monitors are much easier to handle than their predecessors. They are lightweight, weighing about 15 pounds each, and take up less space on the desktop. “I used to have to get someone to help me with the 100-pound monitors but now I can swap them out myself.” Wright said.

In addition, flat panel medical monitors do not generate all the heat that the CRT monitors emitted. “If you had four monitors in one small workspace generating all that heat, there was a higher likelihood of a fluctuation in the video board or a shut down of the workstations,” she said.

Accuracy, or calibration, is also no longer a hassle. “The CRT-type monitors used a calibration puck that had to be attached to each monitor with cables and calibrated manually. The new Barco Coronas have a calibration sensor on the front of the panel so we don’t have to attach anything with cables. It’s all done strictly through software,” said Wright.

Barco’s I-Guard is a quality assurance sensor on the front of the monitor that measures the output of the backlight, to assure the output is always the same, and to do integrated, automated, software-based DICOM calibration on the displays.

In addition, the former calibration method required a bio med specialist in medical equipment to attach and conduct the calibration manually. “I can now do the calibration on them myself. It frees up the bio med people to take care of more technical medical equipment, not the medical computers,” Wright said.

“We also use Hewlett Packard 21-inch monitors for clinical displays in the operating room, the ER and the orthopedic clinics, where they need to look at images closely. They run at 1024 x 768 minimum resolution for clinical display, but some doctors run them higher,” said Wright.

To accommodate fast-paced emergency medical situations, a medical monitor display starts up faster than a common desktop monitor. “Turning on the display immediately drives the backlight into full luminosity, so that radiologists can start working as soon as they turn on the monitor,” Domogalla said.

Through their broad product selection and display technologies, NEC Display Solutions is able to provide some unique offerings to the military medical market. In addition to the full portfolio of MultiSync MD Series 2, 3 and 5 mega pixel diagnostic displays and MultiSync 90 series of review monitors, NEC also offers a number of large screen LCD to address the growing use of large monitors in hospital and OR applications.

The number of hospitals using professional-grade large-screen LCD monitors for dynamic information applications is on the rise. NEC’s largescreen series, includes the 32-inch MultiSync LCD3210, the 40-inch LCD4010 the 46-inch LCD4610, and the LCD5710—the largest professional LCD display available on the market.

More and more hospitals and clinics are using large-screen LCDs in applications such as mapping and digital signage for better dissemination of information and in operating rooms and in nursing stations to gain better control of patient and procedural tracking and for larger medical image projection during surgeries. By using displays such as the MultiSync LCD4010, physicians and nurses are getting instant and vital access to patient information.

“NEC offers their patented X-Light technology. “Standard LCD monitors use a CCFL,” said NEC’s Tim Dreyer. “CCFL lights whitepoint will vary in production lots. This means that two monitors may not look identical even though the light output is calibrated to the same luminance [intensity of light]. Since most grayscale monitors are used in pairs or multiple-monitor configurations, it is important that they have a similar image projection. In addition, as the monitor ages, the whitepoint of the monitor will shift towards a yellow hue. X-Light allows NEC-DS to adjust and keep the x, y [CIE] of the display whitepoint to +/- 0.002, a tenfold improvement.”

NEC-DS uses a patented three-color CCFL architecture and associated circuitry to control the color (whitepoint) of the backlight. By mixing three separate colors of CCFL and using an internal feedback loop, the luminance and whitepoint of the monitor can be controlled over the life of the monitor.

“Other medical display manufacturers match monitors at the factory by measuring every monitor after assembly and sorting them by whitepoint,” explained Dreyer. “With X-Light, since all monitors have the same whitepoint, any monitor can easily be replaced. Even onsite replacement units can be stored and used for easy replacement and service. This result in not only more consistent diagnosis from display to display, but faster, easier and more reliable asset replacement.”

Consistency and stability are important features in medical imaging for a number of reasons. Display users suffer less fatigue when there is consistency from display to display. Additionally, stability within a display assures that anatomy looks the same over time, leading to better diagnostic interpretation.

“Fully automated stability is a technology developed by Siemens that provides both consistency and stability,” said Christine Seymour, business manager, display technologies, Siemens Energy and Automation. “In display design, sensor integration and display calibration are the key elements in achieving the required consistency and stability.”

The fully automated stability technology utilizes sensor location and function as well as integration with a display quality assurance package. The display calibration philosophy behind fully automated stability emphasizes highly precise factory calibration, automated stability checks and annual verification of sensor stability using an external photometer. This technology can directly contribute to diagnostic speed and confidence.

A major health care institution recently did a study on 51 displays that were in use for up to 18 months to test the fully automated stability technology. Using analysis of variance statistical methodology, data was analyzed showing excellent display-to-display consistency. Displays were also predicted to run an average of 11,000 hours before requiring recalibration. The findings were documented in a recently completed white paper.

“The new SCD 21310 3MP, by Siemens, features all of the elements of the fully automated stability system for DICOM compliance, including an internal ISS sensor (integrated stability system), built-in lookup storage and complete compatibility with Siemens quality assurance software SMfit ACT,” said Seymour.

A three-megapixel color flat panel display designed with a high level of brightness and contrast for both color and grayscale medical imaging applications, the SCD 21310 3MP has five internal look-up tables and automatic calibration to a calculated luminance level. Its technology can be adapted to any reading environment.

Eizo Nanao Technologies’ North American product manager, Hideyuki Honda, sees their medical LCD monitor line-up focusing on imaging modalities that require high brightness and high contrast ratios in conformity with required medical standards. “Our monitors are designed for users who have quality controlled environments and ideally require accuracy and consistency using DICOM calibration,” says Honda. EIZO’s diagnostic monitors range from 1MP-5MP for use in every medical imaging modality, with each resolution geared toward specific imaging needs.

The RadiForce G33, for example, is their answer to 3MP monochrome applications in PACS, CT and MRI. This monitor’s most attractive feature is its 12-bit simultaneous grayscale display from a 13-bit look-up table, which translates to a palette of 8,161 grayscale tones from which 4,096 different tones can be displayed simultaneously. This in collaboration with their patented digital uniformity equalizer, a function of their proprietary circuitry which provides backlight luminance uniformity, provides a stable platform for diagnosis.

EIZO also concludes they see more demand in color applications that require high resolution color displays for 3D image rendering, PET, and color MRI and CT work. Honda adds, “These applications require high brightness displays that have a wide palette of colors to produce distinction in diagnostic images.” Their solution is the RadiForce R31, a high brightness 3MP color monitor with 10-bit input compatibility capable of displaying over 1 billion colors.

Also, since there is a vital need to keep image quality consistent and controlled in a medical environment, the company’s QC software that can be bundled with any and all of their monitors to provide control over a network from one central location. This alleviates the tedium and manpower to physically calibrate each monitor individually at each workstation and provides the means to schedule automatic calibrations and testing remotely. This automation translates to a time and cost savings that greatly outweighs the software’s initial expense.

Another area where medical monitors are in growing use is telemedicine, or remote medical care, which uses video conferencing and remote diagnostics to enable telecare. At the VA for example, there are currently 23,000 patients who would be at risk of going into a nursing home if the agency weren’t able to monitor them at home, according to Dr. Adam Darkins, chief consultant, Office of Care Coordination for TeleMedicine.

Remote medical care or telemedicine is part of the VistA program. “We measure a number of vital signs, including pulse rate, temperature, blood pressure and blood glucose, remotely,” he said.

A subset of VistA, called VistA Imaging, enables the communication of visual images throughout the VA. Starting in October 2005, the VA rolled out one of three VistA Imaging components, entitled the Teleretinal Imaging Program, to 104 national sites and approximately 85,000 veterans, with a goal of serving 175,000 veterans within two years.

“Taken by a specialized camera attached to a high resolution monitor, teleretinal images can determine whether a diabetic patient has diabetic retinopathy, an eyesight disease that could lead easily to blindness if it is not prevented by screening using digital retinal imaging,” said Darkins. “Twenty percent of VA patients have diabetes. That’s about one million people,” he noted. Visual impairment is a common complication of diabetes, he noted.

Using the NASA SEWP III contract vehicle, the VA Teleretinal Imaging Program purchased Hewlett Packard L2065 retinal reading workstations that are flat screen, 20-inch, high resolution monitors. For the past year, the program has rolled out the HP monitors to VA clinics and hospitals throughout the country.

To work with the HP monitors, the program also purchased a Topcon Medical Systems digital, retinal camera (based on a Nikon D705 digital camera with 6.2 MegaPixels) to take the retinal images, Topcon IMAGEnet software, and an IMAGEnet to VistA DICOM module. Topcon also provides wheelchair accessibility and on-site installation and training for homebound disabled veterans.

The teleretinal images taken by the Topcon camera are read and diagnosed on the HP monitor to determine whether the patient has or is at risk for diabetic retinopathy. The images are stored and forwarded using the VistA Imaging System.

While some desktop or engineering monitor companies have their place in the medical monitor market, Barco and Planar seem to have satisfied customers. The VA Medical Center in Louisville, for example, uses Barco as its primary vendor. “Barco’s products and customer service are outstanding. In one year’s time, I have sent only one monitor back and I have 35 monitors. The calibration sensor wasn’t working on it and they sent me a replacement monitor overnight” said Wright.

“We are likely to purchase Barco color 3-D monitors. The radiologists will love that because it makes the images easier to interpret and diagnose,” she said.
 
Although most medical facilities are evolving toward one, integrated, network-enabled, electronic medical record for the patient, the reality today is that patient information is still contained mostly on disconnected systems. As the integration of medical systems increases, it seems that the use of large resolution, flat screen, lightweight medical monitors could flourish. ♦

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