PACS displays: how to select the right display technology.

The medical imaging display is a precision instrument with many features not found in commercial-grade displays. The more one understands what these features are and their corresponding clinical value, the better one can make a purchase decision. None of these displays maintain themselves for 5 years or more without some degree of automatic or manual performance testing. Routine calibration conformance checks are beginning to be mandated by the departments of health of many states. Most manufacturers provide mechanisms to perform these checks and keep track of their results, some more easily than others. A consistent display brightness of about 400 cd/m(2) and close conformance to the DICOM curve are the key components of a successful check. Displays are typically characterized by the number of pixels they contain, usually 2, 3, or 5 megapixels, but this is the least useful determinant of image quality. What matters most is the size of the pixels and the size of the whole display, which should be selected on the basis of the typical viewing distance. The farther one's eyes are from the display, the larger the pixels and the overall display size can be while still feeding the eye as much information as it can see. Care should be taken to use the appropriate display in a given setting for the clinical purpose at hand.

Use of mobile devices for medical imaging.

Mobile devices have fundamentally changed personal computing, with many people forgoing the desktop and even laptop computer altogether in favor of a smaller, lighter, and cheaper device with a touch screen. Doctors and patients are beginning to expect medical images to be available on these devices for consultative viewing, if not actual diagnosis. However, this raises serious concerns with regard to the ability of existing mobile devices and networks to quickly and securely move these images. Medical images often come in large sets, which can bog down a network if not conveyed in an intelligent manner, and downloaded data on a mobile device are highly vulnerable to a breach of patient confidentiality should that device become lost or stolen. Some degree of regulation is needed to ensure that the software used to view these images allows all relevant medical information to be visible and manipulated in a clinically acceptable manner. There also needs to be a quality control mechanism to ensure that a device's display accurately conveys the image content without loss of contrast detail. Furthermore, not all mobile displays are appropriate for all types of images. The smaller displays of smart phones, for example, are not well suited for viewing entire chest radiographs, no matter how small and numerous the pixels of the display may be. All of these factors should be taken into account when deciding where, when, and how to use mobile devices for the display of medical images.