In the medical-imaging field, today’s monitors are yesterday’s film. Physicians use them to diagnose, treat, consult, and teach. As such, image quality should be a top priority when purchasing monitors?but it shouldn’t be the only factor considered. If the image cannot be seen well due to a poor environment, inadequate compatibility, or unavailability, then the image might as well not be seen at all.
What can facilities do to make sure their technological eyes continue to provide reliable windows inside their patients? Ask the following five questions when shopping for monitors.
1) Quantity: Exactly how many monitors are needed and where?
A facility should clearly define its workload to determine how many of each type of monitor it will require, according to Geert Careein, product manager of displays and systems at Barco NV (Kortijk, Belgium). A larger hospital will likely need more workstations, but workload might be determined more easily by calculating the number of exams done annually, monthly, and/or daily. The more exams conducted, the more workstations that will be needed, and the more data the server will need to handle.
The number of radiologists on staff also will influence how many workstations will be needed. “If you have ten radiologists on staff who will want to diagnose simultaneously, you will require more workstations than if these physicians work in shifts,” Careein notes.
Similarly, the number of staff that will need access outside of radiology must be considered. Patient-examination areas, operating rooms, and lecture halls could all need to be equipped.
2) Image quality: What applications are in use?
The application will determine the image quality needed?different modalities and uses require different levels of image resolution, as well as contrast and technology.
Todd Fender, product line manager for specialty marketing at NEC Display Solutions of America (Itasca, Ill), describes the two types of monitors: primary monitors (which are used for diagnostic work and require medical certification) and review monitors. “[The latter] are used in such areas as surgery and nursing stations and can be any good-quality monitor,” he says.
Generally, diagnosis will require image resolution of 2 or 3 megapixels (MP); clinical applications can use less. Mammography requires the highest level of resolution: 5 MP. PACS diagnostics need 3 MP. CT, MR, and PET are best read at 2 MP?although, in some instances, CT can get away with 1 MP. “In theory, a one-megapixel display is sufficient for CT; but most professionals use two megapixels, because they can look at several images or sequences simultaneously,” Careein says.
Image quality also is affected by brightness and contrast, both of which can be different according to the screen technology. “All LCD monitors are not the same from an image-quality standpoint,” Careein says. “The cheapest processors typically don’t have a good viewing angle, and the image will look different. Medically certified companies offer the best LCD technology,” he adds, noting that this technology is also more expensive.
But as LCD technology has improved, its price has come down; as a result, its use has increased. Forecasters predict that eventually, CRTs will become obsolete. Currently, they are primarily used in mammography, where a high resolution and contrast are necessary, and LCD technology is still expensive.
Another difference lies in the color of the light; monitors can be clear- or blue-based. “The screen of the clear base is made to look more black and white; that of the blue base has a blue tint. Usually, physicians prefer the type they were trained on in medical school; however, generally speaking, blue-based monitors make up about five percent of the US market,” says Fender, who notes that blue-based monitors are much more popular in Europe and encompass roughly 95% of the market.
3) Ergonomics: Is the image comfortably visible on the monitor?
Whether in Europe or the United States, facilities need to consider the local environment in which the monitors will be used. “When implementing a PACS solution for the first time, it’s very important to have proper reading rooms. This parameter is often overlooked,” Careein says. For instance, if a window in the room is casting direct sunlight on a monitor, the available contrast will be lowered, and the image quality will be negatively affected.
Not only should the impact on image quality be a concern, but also future compliance. According to Careein, if and when standards become mandatory, an inadequate reading room will fail the test. However, ergonomics can be an issue, policy or not. Physicians need to be able to comfortably view the images. Ergonomic workstations can reduce potential work injuries and strain both inside and outside of the radiology department. For instance, in the operating room, if the monitor is mounted on the wall for viewing at a distance, it should be larger in size.
4) Speed and performance: Will calibration or compatibility issues affect performance?
Speed and performance also should be considered, as they can have a significant impact on workflow and productivity. Systems that self calibrate help to ensure maximum and efficient performance as well as quality control.
“DICOM calibration is important, and there is still a lot of adaptation necessary,” Careein says. “But hospitals with PACS have, over the years, become concerned with image quality and have implemented quality tracking and good DICOM calibration.”
Fortunately, most monitors now self conform, says Joey Sanchez, marketing/PR coordinator for Eizo Nanao Technologies Inc (Cypress, Calif). The company offers calibration systems with its monitors; DICOM calibration is done in-house before shipping and can be monitored over the network by a hospital technician from one location.
|
This kind of remote monitoring has become more common. Barco offers this capability as well, as does Totoku North America Inc (Irving, Tex). “It is possible to manage the operational status of all the displays from one location,” says Mark Yoshida, sales engineering and marketing manager for Totoku. “The system monitors the display performance, such as the last calibration time, operating hours, and abnormalities.”
NEC Display Solutions’ monitors have an internal setting to keep them calibrated; free software allows monitoring. “In theory, hospitals won’t need to calibrate unless they are following specific standards or an in-house policy,” Fender says.
Careein laments the lack of national standards, noting that some regions, such as Japan and the European Union, are developing acceptance-testing standards. “If a system is not properly calibrated, it’s easy to show how a diagnosis can be missed,” he says. Compatibility issues also can affect viewing. “At first sight, compatibility might not seem to be an issue, but there is a difference in the image quality,” Careein adds. He also notes that digital monitors, though not perfect, will give a better image than an analog system.
Software also will influence performance. “Does the software take away from the performance of the system?” Careein asks. “If the software is slower than the hardware and can’t keep up with the sequence rate, it might skip images or add artifact,” he says, citing a commercial Dell display as an example. “It would never be able to keep up [with medical imaging],” he says.
To eliminate artifact in moving images, Barco integrates a triple buffer into its display. Also, vendors often are willing to collaborate on solutions. “We will work with other vendors, developers, and service providers to be sure that our monitor system will be compatible. If a customer is using an unknown system, we’ll go to its vendor to test the equipment and modify it if necessary,” says Sanchez of Eizo’s policy.
Fender states that NEC Display Solutions does not aim to exclude vendors either. “We do not want to force a proprietary solution on users,” he says. “So even though our new series is marketed with a preferred video card, we offer other choices to match different systems. Customers can compare card benefits, features, and costs.”
5) Vendor and product: What is the total cost of ownership?
Customers also will want to compare vendors and prices, looking at experience, products, and services. Without question, monitors used for medical imaging should be purchased from companies that serve the medical market. But a facility does have the option of selecting a company outside of its PACS vendor?though most facilities don’t.
“Roughly 70 to 75 percent of facilities [buy monitors] through their PACS vendors,” Careein estimates. Most institutions want a turnkey solution. Going with the PACS vendor means monitors can be included in the service contract and, in some cases, that uptime is guaranteed. “Some vendors will guarantee a 97- or 99-percent uptime, meaning that staff will not have to lose time swapping displays for repair,” he adds.
Of course, some facilities will decide to purchase monitors from an independent vendor. Frequently, these institutions have a strong information technology structure or are updating monitors separately.
The life span of monitors is discussed in usage hours and is often around 30,000 hours. Whether the product is used 24/7 or less frequently will affect how long it lasts. Warranties vary depending on the company and product, but typically stretch anywhere from 1 to 3 years; some are defined in usage hours. Totoku’s Yoshida notes that warranties typically provide free repair or replacements if repair is not possible within the warranty period.
Facilities also should consider service options. Fender suggests that administrators find out how long it will take to receive replacements. If a monitor requires more service than a simple board swap, it will have to be returned to the manufacturer.
“If the monitor is used in a double configuration, as is frequently the case in radiology, the replacement monitor will need to match the light of the monitor still working,” Fender explains. When new, the light of different monitors can display color differences. Over time, a monitor’s backlight will fade. The change will be gradual and not noticeable unless compared to a newer monitor. In some cases, this can pose a problem after servicing, when the replacement monitor is noticeably different; hence, both original monitors must be switched out.
NEC Display Solutions has introduced technology to work around this problem, ensuring that every monitor out of the factory continues to look the same throughout its lifetime. The technology works by taking color temperature readings from the bulbs every 20 milliseconds and adjusting for the aging process, allowing the monitor to hold its original white point. “Every monitor should look the same,” Fender says.
Of course, all of these factors need to be weighed against price. Fender cautions institutions to remember that comparing total cost of ownership can be more economic than simply comparing initial price. He adds, “It’s an investment, and a monitor’s features and benefits are designed around the total cost.”
Renee DiIulio is a contributing writer for Medical Imaging.
