Three Monochrome Displays From a Single, True Color Video Display Controller Ulrich Raft and Victor M. Spitzer Some nuclear medicine computer displays, as well as environments. Although the concept of PACS many image processing workstations are "true color" has become quite clear in the last decade, its machines characterized by independent memory and implementation has been rather slow for vari­ grey scale mapping for each of the red. green and blue color channels. Other color image display systems ous reasons. Substantial technological problems produce a color image from a single grey scale map involving storage, transmission, display, and composed of red, green, and blue intensity values digital interaction (input/output) remain to be ["pseudo color"). In the true color system the final solved, display in particular. With the growing image is obtained by overlays of three independent number of "personal" workstations (Digital color images. In an effort to present complete nuclear medicine studies for diagnosis from cathode-ray tubes Equipment Corporation, Boston, MA, Sun Mi­ (CRTs) we have employed a true color display to crosystems, Incorporated, Mountain View, CA, present three times as much spatial information as the Hewlett Packard, Palo Alto, CA and Silicon system was designed for by directing each color Graphics, Mountain View, CA just to name a output from the display controller to a different mono­ few major manufacturers) true color display of chrome black and white (b/w) monitor. Therefore our system displays a 512 x 512 x 24-bit true-color image. digital data is available on relatively affordable orthree 512 x 512 x a-bit monochrome images. or any desktop machines. Realizing the potential of combination of smaller size matrices. Monitor require­ these color display stations to triple the amount ments, cabling, and general software considerations of monochrome spatial information, the goal in are detailed here. The ability to display complete this study was to optimize the display aspects of nuclear medicine studies on CRTs (as currently pre­ sented on film) has been provided by adding monitors a PACS environment such that the maximum and software revisions to a commercially available monochrome display capability is achieved. An nuclear medicine computer system. example will be given based on the digital data Copyright © 1997 by W.B. Saunders Company volume and display needs of an all-digital nu­ clear medicine department. While certain de­ KEY WORDS: nuclear medicine imaging, display sta­ tions, PACS,true color imaging systems. partments, like diagnostic x-ray are beginning to incorporate digital techniques in their proce­ ITH THE INCREASE in the number of dures, others, like CT, MRI, and ultrasound, W digital diagnostic imaging procedures in are more suited to digital display due to the radiology and the rapid development of low cost inherent digital nature of the image formation. display technologies and networking, a serious However, the volume of data obtained in CT, trend toward "filmless" departments can be MRI, and ultrasound is hindering, for the time foreseen. The increasing number of digital mo­ being, the fast development of a filmless depart­ dalities (computed tomography [CT], ultra­ ment We will discuss the requirements of sonography [US], magnetic resonance imaging PACS displays and illustrate a possible contribu­ [MRI], digital subtraction angiography [DSA]) tion to a cost effective monochrome CRT dis­ strongly favors the development of Picture Ar­ play capability for nuclear medicine. chival and Communication Systems (PACS) REQUIREMENTS OF PACS DISPLAYS Focusing on the display environment of PACS From the Division of Radiological Sciences, University of systems, the following considerations should be ColoradoMedicalSchool and InternationalCenterfor Cancer addressed: (1) Displays and viewing stations and DevelopmentalBiology (InternationalCenterfor Cancer, Santiago de Chile-Denver, USA-Madrid, Spain); and the must have associated large memories to display DepartmentofCellularand StructuralBiologyand the Depart­ complete patient studies. (2) Displays also have ment ofRadiology, University ofColoradoMedical School. to be large enough to accommodate previous Address reprint requests to Ubidi Raff, PhD, Division of studies or correlative studies obtained from Radiological Sciences, Box C-278, University of Colorado different imaging modalities (US, CT, MRI, MedicalSchool, 4200E 9 Ave, Denver, CO 80262. Copyright ~J 1991by w.s. SaundersCompany NM, DSA, etc) and may also include correlative 0897-188919110401-0006$03.0010 anatomical atlas images.' (3) Rapid access to all 28 Journal of Digital Imaging, Vol 4, No 1 (Februarv), 1991: pp 28-38 DISPLAY STATION USING COLOR VIDEO CONTROLLER 29 the data is mandatory. An access time to equal nuclear medicine department may have the or beat is the current speed at which films are following display requirements; retrieved on standard viewboxes or alternators (1) The ability to display complete patient and the time required to retrieve correlative studies including static and/or dynamic images. studies from different radiologic modalities. (4) The static images may be 128 x 128 or 256 x Some imaging modalities require cine-displays, 256 matrix images with 1 to 12 images per study. the capability to show a sequence of frames The dynamic portion of our studies produce 16 from different time intervals. (5) Color images to 100 frames of 64 x 64 matrix: images. These maybe utilized to enhance features in otherwise may either be filmed as static images, archived monochrome images (nuclear medicine, Dop­ on video tape for later playback or stored on the pler ultrasound, MRI and three dimensional system disk for cine-display. If filmed, 32 se­ data presentation). Pseudo color is often used lected or summed images with 64 x 64 resolu­ for such enhancement purposes. Pseudo color tion are recorded. In most cases, the processing image display uses only one 8 bit image plane of dynamic studies and SPECT acquisitions directed to a single color monitor. Color graph­ generate an additional 2 to 4 graphs and/or 32 ics have also become a standard feature of 64 x 64 views that also need to be displayed display stations in medical imaging for enhance­ alongside the acquired images. In addition, a ment purposes. Display requirements are simi­ comparable number of functional images may lar to those for pseudo color images. (6) Image be generated in certain cases to be displayed in manipulation involving basic digital image pro­ cine mode. If whole body images are obtained, cessing techniques: windowing, zooming, two images, at least 256 x 512 for the anterior/ smoothing, interpolation, rotations, inversions, and mirroring of images is required." (7) Anno­ posterior and posterior/anterior views respec­ tation of all digitally displayed data is manda­ tively, must be displayed. Thus nuclear medi­ tory. (8) Photography of images still remains a cine studies will have a variety of display requirement for most interdepartmental needs requirements ranging from 64 x 64 dynamic and referring personnel, therefore any data on a acquisitions to high resolution 512 x 512 im­ video screen should be available for hardcopy ages. Often images from previous examinations recording. must be displayed alongside the current study for comparison during a reading session. For REQUIREMENTS OF NUCLEAR MEDICINE example, renal transplant patients require fre­ PACS DISPLAYS quent hippuran and diethylene-triaminepen­ taacetic acid (DTPA) studies to monitor tubu­ For this work the above PACS display require­ lar necrosis, rejection, and cyclosporine toxicity.' ments were applied to the typical case load of Oncology patients are screened with bone scin­ the nuclear medicine department at the Univer­ tigrams at regular time intervals in search of sity of Colorado Health Sciences Center. The secondary metastases to stage possible evolu­ department consists of four scintillation cam­ eras, two of them with single proton emission tion of primary cancer. computed tomography (SPECT) capabilities, (2) The ability to display correlative studies all interfaced to two acquisition and processing from different imagingmodalities. Nuclear med­ computers (Picker International PCS 512 [Cleve­ icine must be able to accommodate large size land, OH] and DEC PDP 11/34A GAMMA 11 matrices from other imaging modalities. These system [Digital Equipment Corporation, Bos­ may include digitized chest x-rays, ultrasound, ton, MA] with Picker VSV02 display). An aver­ CT, and MRI. Presently the use of digital chest age of 15 procedures per day is completed. The x-ray and ultrasound are not widespread, and a need for nuclear medicine PACS displays be­ typical MRI or CT study requires the display of comes even more evident if one notes that all 40 to 60 images. MR imagesare mostly256 x 256 new camera-computer systems are designed for while CT images are in general displayed in complete digital data acquisition including total 512 x 512 mode. body imaging. With this in mind a "filrnless" (3) Rapid access to all images in a study and 30 RAFF AND SPITZER to all studies of interest for a specific reading has to show at least the patient's name, type of session. The retrieval and display of images study, acquisition date and time, appropriate from the display's mass storage is not instanta­ scales, and other identification commonly used neous, however, single image access time should by physicians when reading scintigrams. compete with alternator