The use of picture archiving and communication systems (PACS) and primary soft-copy interpretation in radiology is growing rapidly. The authors present a cathode ray tube (CRT) acceptance test and quality control (QC) program developed over a 5-year period on the basis of experience with multiple PACS and CRT vendors. The CRT QC procedures address monitor cleanliness and setup, qualitative image quality, and quantitative luminance and color measurements. Required materials include a photometer with luminance and color probes and 100%-video, flat-field window and test images from the Society of Motion Picture Test Engineers (SMPTE). Luminance was found to change over time for all gray-scale CRTs examined, which necessitated quarterly recalibration. The phosphor color of these monitors was also found to change, but changes were consistent and slow enough to warrant only annual measurements. Color measurements were found to be especially useful at initial setup and for CRT replacement. Use of this program allowed standardization of absolute luminance of individual CRTs, matching of phosphor color for multimonitor workstations, and systematic tracking of image artifacts. Implementation of a QC program is strongly recommended owing to the dynamic nature of CRT displays.

T HE USE OF ELECTRONIC display devicesfor primary diagnostic interpretation of digital images in Radiology is becoming commonplace. For all equipment involved in image acquisition or display, it is typical practice in radiology that quantitative measurements of physical parameters affecting image quality be made for the purposes of new equipment selection, acceptance testing, and quality control (QC). Electronic displays are problematic in that routine measurement of display parameters other than luminance are difficult and expensive to obtain, especially in the field. To address this difficulty, we are investigating a method for quantitatively evaluating the overall quality of electronic displays. This technique is very similar to traditional contrast-detail (CD) methods'? in that many factors affecting image quality (including contrast sensitivity, noise and modulation transfer) are included in an overall quality measure. A technique acceptable for the purposes of new equipment selection, acceptance testing, and QC would allow the quantitative evaluation of a device in 30 minutes or less with a precision of about 10%. Such a technique would also allow quantitative evaluation of the effects of display set-up and environment, such as maximum display luminance and ambient room lighting.The purpose of the current work is to make an initial pilot investigation of the feasibility of using contrast-detail techniques to provide overall quantitative quality evaluations of electronic displays. Our data may also allow us to make a preliminary evaluation of the importance of maximum display luminance. METHODSContrast-detail methods 1-3 involve the presentation of simple targets on a uniform background to a group of observers. The targets have varying contrast and size. For each target size, the observer indicates the contrast threshold at which the target is just visible, and in most cases, interpolation between actual image contrast is encouraged. We incorporated the idea of requiring the observer to indicate the area of the test image in which the target is seen as proof that the target is actually visualized.' Six sets of 8-bit per pixel test images were created. Each set consisted of eight images, each image corresponding to one of eight possible square target sizes. The target sizes were 1,2,3,4, 7, II, 17, and 27 pixels. In each test image, eight rows of four test areas were present. Each row corresponded to one of eight possible target contrasts. The target contrasts were I, 2, 3, 4, 7, II, 17, and 27, denoted as the pixel value difference between the target and the background. For object size of I pixel, larger contrasts were used. All targets were darker than the background to enhance sensitivity to cathode ray tube (CRT) glare. Each test area presents the target in one of four randomly selected quadrants. The test areas are defined by low contrast borders. A test image set is schematically illustrated in Fig I. The test image sets were created using a common PC paint application (PaintShop Pro. Version 4, lASC I...