Monitors that don’t meet display standards could compromise diagnoses.

As digital imaging technology sweeps clinical specialties, many hospital enterprises share the same goal: the ability to display any image, from any clinical specialty, at any computer as part of the patient’s electronic medical record. To reach that goal, enterprises must invest in more PCs with image-display capabilities. As enterprises seek methods of containing costs while supporting technology transitions, they will logically consider a centralized purchase of display devices and PC computers in order to take advantage of economies of scale. However, if the clinical requirements for data display are not supported properly, problems can arise on the medical side of the enterprise.

Often, maintaining PACS workstations and clinical workstation hardware falls under the overall hospital information technology (IT) management program. While this situation most often occurs in the clinical areas outside of radiology where a large number of multipurpose PCs also serve as image display devices, this situation is increasingly common in the radiology environment where PACS workstations are managed as high-end computers instead of medical display devices.

If IT managers, engineers, and technicians are not schooled in the concepts of display quality and medical device safety considerations, they may fail to adequately match the clinical display and safety requirements to the procurement, deployment, and support activities. This can result in poor quality image and data display, which could compromise diagnoses and treatment decisions. It could also lead to safety-related issues that place patients and staff at risk. There is a growing need for general education in medical computing and, more specifically, in the data display and safety requirements for medical PCs.

Figure 1. Operating room displays with 1.2 MP color monitors with DICOM calibration and special environmental certification.

Viewing Requirements

There are large differences in the data sets created by different image acquisition systems, which must be accommodated if the spread of digital imaging throughout specialties is to move forward without producing serious negative side effects. Two examples of where such problems arise are:

  • An ER physician using a laptop computer display monitor for diagnosing a potential pneumothorax.
  • A pulmonologist using a standard 1.2 megapixel (MP) display monitor to look at chest images to determine the presence of lung nodules.

In these two examples, the danger is that these physicians will not see fine image details that are present in the image data set because the display device is incapable of delivering them in a humanly perceivable manner.

The two key factors in a display device are spatial resolution and contrast resolution. The spatial resolution is determined by how many pixels a display device has, while the contrast resolution is determined by the brightness range of the monitor plus the use of DICOM calibration. Display users and managers of medical display technology should be familiar with these concepts and apply that knowledge to the appropriate procurement, deployment, and servicing of medical display devices.

Different physicians use different data types and therefore require different display devices. Additionally, some physicians render diagnostic reports or make treatment decisions based on the data they see and, therefore, must have their monitors optimized to that task; others use images and the reports together as data points in a differential diagnostic process and do not require the highest quality of image display.

Table 1 shows the different viewing requirements for a variety of specialties. The need to display both high-resolution and low-contrast data will drive the use of high-end diagnostic displays, as are commonly seen in radiology diagnostic workstations today. The display of high-contrast, low-resolution data can be performed faithfully by good-quality, off-the-shelf display monitors made by companies such as Dell, Sony, and NEC. Only a few surgical specialties require the ability to display color motion images, and these display devices usually will be provided by the imaging equipment vendor as part of a medical system.

Special Considerations

It is imperative to consider the safety issues associated with all equipment, especially devices in operating rooms, treatment rooms, procedure rooms, trauma rooms, and ICU patient rooms. When placing workstations in these areas, consult the hospital safety manuals for equipment specifications and testing requirements. Hospital safety committees should look specifically into the management of computer deployment in these areas and the provided guidance with reference to NFPA99, Standard for Healthcare Facilities.

Due to the complex mixture of data types displayed in a clinical environment, specialty workstations are often made up of a CPU coupled with more than one monitor. Those monitors can be mixed to develop the ideal video space for the specific data types needed. In radiology, diagnostic and quality control workstations are often multimonitor workstations with different mixes of display types to match the data sets being viewed (see Table 2).

A radiologist, like many physicians, must be able to access and display information from several sources simultaneously. The mix of data to be displayed often has the following attributes: color and monochrome data, textual, diagrammatic, and pixel-based images.

Radiologists usually have live feeds from a variety of applications, including HIS, RIS, PACS, voice recognition system, e-mail, Internet-reference sites (eg, Google, MD On-line), teaching folders, and online PDR. A mix of display devices is required to optimize the display of these data types and to facilitate efficient workflow for the radiologist. Two or four high-resolution, high-brightness, DICOM-calibrated, grayscale monitors are often coupled with low-resolution, medium-brightness, noncalibrated color monitors on the same CPU. This creates a versatile and unified video space for displaying all data types.

This mix of display attributes allows the viewing applications used on the workstation to place large matrix data such as CR images on the high-resolution monitors and the low-resolution objects such as scanned documents and historical reports on the low-resolution monitor. The proper mapping of data to monitors is important from the quality assurance perspective, as the radiologist should have the data displayed in as near to full fidelity as possible so as not to require manual adjustment of the images to see the full data set. Manual adjustments take time and can lead to incomplete data viewing if the user is not fully facile in the use of the workstation tools such as Window/Level, Zoom, and Pan. While these may seem like old lessons to be discussed in 2007, there are good reasons to review these principles:

  • Lessons learned in developing radiology workstations now can be applied to the deployment of clinical workstations at great cost savings but with no loss of functionality or image quality.
  • Many users and technology managers do not appreciate the risk of improper data-to-monitor mapping and make purchasing decisions based on cost.
  • Many PACS and mini-PACS applications have viewing client software that allows PACS images to be viewed at any PC that has network access to a PACS. If not controlled, this access allows medical images to be viewed in physician’s offices, at nursing stations, at physician’s homes, and even on laptop computers that are also used for charting and patient registration and e-mail.
  • Hospital computers and their display monitors are often considered the domain of nonmedically trained support staff that do not have the skills and knowledge to procure and maintain medical displays. Quality-control (QC) workstations in each modality area should similarly have the proper mix of display monitors to see the required details of the work that the QC technologist performs. A good QC workstation structure in a CR/DR area would consist of a 1.2 MP monitor coupled with a single 3 MP monitor. This mix provides the high resolution needed to perform image QC as well as the lower-resolution color-capable viewing of PACS worklist, RIS data, and scanned documents that are all part of the radiology QC workflow.

While access to information is a goal of medical informatics, take care to ensure that the data is presented with the required fidelity. Physicians, technologists, and technology managers should be familiar with the appropriate display of images and associated data.

One such consideration is DICOM grayscale display standard (DGSDS) calibration, which allows the output response of display devices to conform to a human’s ability to perceive all of the data in an image. Calibrating display monitors to the DGSDS takes time, special tools, training, and access to the workstations. This level of effort cannot possibly be given to all of the hundreds—or even thousands—of PCs used to display medical images. Instead, designate the clinical specialties that need workstations with higher-level display capabilities, and procure, deploy, and service them accordingly. In addition, place calibrated clinical workstations in designated locations for common access by authorized users—this makes the displays available, if needed, without overspending.

To reduce the high cost of human resources and test equipment to perform periodic display calibration, purchase displays that have imbedded calibration sensors and reporting software. Additionally, separate the task of performing display quality services from the procurement, distribution, and general PC servicing tasks. The clinical engineering and IT departments should develop a working agreement to distribute service tasks according to their respective training, skills, and resource availability.

There is good news in the midst of this data display and service responsibility confusion. The ever-improving manufacture of flat-panel displays and PC technologies makes it easier to meet the display quality needs with either off-the-shelf consumer products or lower-cost medical displays.

Currently, flat-panel displays that satisfy the requirements for all user types are available. The biggest improvement is coming in the form of mid-level color flat panels (2 MP), which are commercially available and have the required brightness range and spatial resolution to satisfy the data viewing requirements of most nondiagnostic physicians. A single 21-inch, 2 MP color monitor with DICOM calibration satisfies the majority of clinical user requirements for both medical images and other data forms. Raising the general standard for common-area clinical workstations to include such a monitor, and provide DICOM calibration where appropriate, could control the issue of inappropriate display usage.

Figure 2. Diagnostic radiology workstation with four calibrated 3 MP grayscale monitors and a single color monitor.

Figure 2 shows a diagnostic radiology workstation that has four DICOM calibrated 3 MP grayscale displays matched to a single 1.2 MP DICOM calibrated color display. Onboard DICOM calibration assists with maintaining the proper display characteristics. High-quality 2 MP color displays like these can faithfully display color and grayscale images as well as text. The spatial resolution is just right to use as a clinical viewing workstation. Single-monitor versions also can be used as well as a mix of 1.2 MP monitors and higher-resolution types, as is done in radiology. The needs of each clinical area should be the driving force in determining the mix.

Specialty Clinical Areas

While most nondiagnostic data viewing workstations can be constructed from off-the-shelf PC components, commercial products, or the standard “medical grade” monitors sold by several manufacturers, some areas in the hospital require special workstation designs and monitor specifications. These areas include operating rooms, trauma rooms, procedure rooms, exam rooms, ICU bedsides, and laboratory workrooms.

The special issues associated with these areas include space constraints, workflow requirements, high ambient lighting, wet environments, disinfecting requirements, high-oxygen concentration areas, and flammable liquids locations. Considerations may also need to be made for electrically sensitive patients.

Standard PCs may not meet the safety requirements posed by these environments, and the safety managers for the facility should be consulted when planning deployments in these areas. The clinical engineering department, the biomedical maintenance team, or the supporting vendor usually installs and maintains the equipment in these domains (excluding purely administrative equipment). A centralized workstation management program for display monitors should require an overlap in servicing schedules and tasks between IT and clinical engineering departments to ensure that the proper specifications are used in these areas and that qualified staff perform periodic safety testing and calibration with the proper tools and instruments.

Figure 3. The sample workstation in Figure 3 is a Planar e4c. It is a 40-inch diagonal display and operates like two side-by-side 2-MP 20 inch color monitors.

Space constraints can be resolved through wall and ceiling mounting of workstations and monitors. High ambient lighting in these areas causes a loss of contrast ratio and, therefore, requires higher brightness range on the display used in these areas. In cases where the display needs to be more than 10 feet from the user or a patient, such as in an operating room, a larger screen will be required to support image viewing. Some companies are now manufacturing wet environment-compatible larger format displays. Figure 1 shows how LCD monitors, which have special environmental and electrical specifications, can be used within the hazardous area boundaries in an operating room. These same monitors could be used in the construction of workstations for use in the other special treatment areas.

Teleradiology, which allows on-call physicians to review images from home when necessary, is becoming more popular. Again, this requires the appropriate display. If the hospital is not willing to install a diagnostic workstation in each physician’s home, a high-end laptop computer with a DICOM-calibrated high-resolution display can be provided to the on-call physician along with the on-call pager.

The sample workstation in Figure 3 is a Planar e4c. It is a 40-inch diagonal display and operates like two side-by-side 2 Mp 20-inch color monitors. An alternative to this approach is to purchase a very high-end laptop, such as the DELL XPS M2010 in Figure 4 (which has the minimum required resolution and brightness), calibrate it, and have it checked out by the physician on call.

Figure 4. Two workstations in an emergency department. Each has two DICOM calibrated grayscale 3 MP monitors.

Training Plan

A variety of display types is required to achieve appropriate data and image display across the enterprise. Planning factors for determining the proper monitor for a given area include:

  • The type of data to be displayed (text, images, color, grayscale, high-resolution, motion)
  • The purpose of the display (diagnostic, clinical, reference, administrative, tele-radiology)
  • The need for calibration services and safety testing (clinical engineering, physics)
  • Special environmental conditions and packaging (mounting, electrical safety considerations, disinfection, flammable liquids or gases)

No matter which display types are used, establish a training program to educate users, managers, and maintainers on the differences in display quality, appropriate use, and servicing requirements. As part of this education program, insert a series of test patterns into the various PACS used in the enterprise, in order to evaluate DICOM grayscale calibration and color calibration, as well as perform a simple test of the monitor’s ability to display high-resolution, low-contrast images. A SMPTE pattern or equivalent, can be displayed easily by users on any PACS-capable PC to get a quick sense of the monitor’s image-display capabilities. For a comprehensive discussion on image calibration and testing, read the American Association of Physicists in Medicine (AAPM) Online Report #3. This document does an excellent job of explaining the nature of image display devices and recommending test routines for both acceptance testing and periodic quality control.

Aligning the appropriate quality data display devices with clinical and administrative functions, while satisfying critical safety standards, is both a challenge and an opportunity. Given the proper set of design factors, such a program can be implemented, providing the two major divisions of the health care organization (clinical and administrative) work cooperatively through the planning, implementation, and ongoing operational phases of the program. In the emerging era of the electronic medical record, where users will get nearly all data from a computer display, such a program can be the source of very significant cost savings as well as a method of establishing and maintaining image display quality.

John Romlein, MS, is managing partner of Qualiteering Labs LLP, Thurmont, Md.