February 9, 2009
Buying Imaging Displays — Eight Things to Consider
By Harley Firth
Vol. 10 No. 3 P. 6
While some buyers may emphasize price or advice from their PACS vendor, there is a fairly simple process that helps determine the appropriate display system for any application. It begins and ends with one question: Does this system meet all of my needs?
Beware if a supplier’s initial words are “you should,” “our systems,” “this product,” or a “me” statement. A vendor’s first sentence should be, “What do you need these systems to do for you?” With this in mind, your display selection should be based on the following factors in this order of importance:
1. Image resolution. The key factor for determining the necessary display type should always be the resolution of the images that will be read on it. High-resolution images, such as CR, DR, and mammography, are more accurately represented on high-resolution displays. Lower resolution images, such as CT, MR, and ultrasound, can be viewed with greater efficiency and accuracy on displays at lower resolutions. This is not to say that high-resolution displays should not be used for low-resolution images. It is simply not necessary to use high-resolution displays (3 and 5 megapixels) if the majority of the images viewed are 512 X 512 or less. To present 512 X 512 images on a 3-megapixel display at full resolution, you will need to display 12 images at a time in a three across and four down matrix, which may present too many images on the screen at one time for some radiologists. A 2-megapixel LCD, however, can display six full-resolution images at a time in a two across by three down matrix and is less costly than the 3-megapixel solution.
2. Contrast and brightness requirements. Contrast and brightness requirements for image types viewed by radiologists can be met by many displays when they are new, but don’t be fooled by advertised specifications. Ask your vendor for a guarantee that their displays will meet your brightness and contrast specifications for the length of time you plan to own the displays. For example, if you require a brightness of 450 candelas per meter squared and a contrast ratio of 500 to 1 for the life of your displays (estimated at three to five years), ensure that your vendor guarantees the product will meet these specifications. If the vendor can’t, that could signify a pure sales pitch rather than a product customized for your needs.
3. Display purpose. We often confuse purpose with desire. If a display’s purpose is to provide diagnostic-quality images throughout its life, then the selected displays should meet the resolution, brightness, and contrast requirements for that specific purpose. However, if the product is being used for clinical review, the resolution, brightness, and contrast requirements can be relaxed.
4. User confidence. One factor that’s often overlooked is whether the radiologists or clinicians who will use the displays will have confidence in their ability to meet users’ needs. Before selecting the display solution, check with the users to determine their specifications.
5. Environment. The viewing environment may affect your choice of display types. Reading rooms and offices are relatively easy to plan for, but if the emergency department, operating room, trauma, or patient care areas of the hospital require displays, other factors must be considered. When deploying displays in these areas, involve the department housing them and the biomed department. Displays for these specialized environments are designed with protective panels for impact resistance, sealed bezels to prevent liquid ingress and permit cleaning and disinfection, and low leakage currents for use near patients.
6. Conformance and calibration. Display vendors will tout their quality control (QC) and quality assurance (QA) software and the capabilities of their displays to meet the DICOM, the ACR, and the American Association of Physicists in Medicine Task Group 18 recommendations throughout their life cycle. Remember that once the purchase has been made, these displays become your responsibility—and there is no system available to date that can do it all. Don’t let yourself be convinced otherwise. Ask tough questions about front and rear photometer quality, manual testing recommendations, network management software, and what the vendor’s responsibility is when displays do not meet compliance standards. Ensuring that your displays provide the highest quality images possible throughout their life should not be taken lightly.
7. Cost of ownership. Cost represents a combination of purchase price, warranty coverage, service guarantees, conformance and calibration, and replacement planning. It can also be defined as life-cycle management. A good vendor will have an excellent technical support team (capable of on-site consultation and installation) available 24/7, an advance replacement program to prevent downtime, and the ability to train customers and provide a robust QC/QA program to ensure that displays maintain DICOM compliance throughout their life. A $1,000 display may look attractive on paper, but if it cannot maintain DICOM compliance, only lasts 24 months, and doesn’t have any form of replacement program, it may actually be more expensive than the $2,000 display that has a five-year warranty, guaranteed DICOM compliance, and a service plan that meets your needs.
8. PACS vendor recommendations. Most PACS software was written with open standards and, therefore, the operation should not depend on the types of displays used. PACS vendors who demand that certain displays be used or purchased from them directly need to be questioned thoroughly. In most instances, these PACS vendor “approved,” “tested,” or “validated” display systems equate to business-building tactics. Select display systems have been tested and validated by the PACS vendor, but the vendor needs to detail the testing and validation process for the user’s benefit.
You will face many challenges and considerations when selecting a medical-grade or diagnostic-quality display system. Be sure to choose a vendor that will take all of these factors into account when consulting, supporting, and developing your healthcare-specific display solution.
— Harley Firth is vice president of global sales for Canvys, a division of Richardson Electronics that develops healthcare-specific display solutions for diagnostic and clinical review, trauma centers, surgery suites, and modality-specific applications.