Donald V. Smith

Hardware and Software Requirements for a Picture Archiving and Communication System's Diagnostic Workstations

Electronic systems (picture archiving and communications systems [PACS]) for image and multimedia data distribution, archiving, and transmission, represent the future of radiology. The workstation is the point of contact between a PACS and the radiologist or referring physician. Therefore, the acceptance of PACS is highly dependent on workstation functionality and performance. This paper, based on our experience in evaluating commercial workstations and on a review of recent literature, describes hardware and software requirements for diagnostic workstations that could be used for making primary diagnoses in a radiology department. Requirements for PACS workstations for use in referring clinics are also briefly described. These workstations must be able to handle the large volume of images to be viewed efficiently, add new functionality to improve the productivity of physicians, technologists, and other health care providers, and provide enough flexibility to allow the electronic systems to grow as medical imaging technology evolves.

Lessons learned and two years clinical experience in implementing the Medical Diagnostic Imaging Support (MDIS) System at Madigan Army Medical Center

The Medical Diagnostic Imaging Support System at Madigan Army Medical Center has been operational in a phase approach since March 1992. Since then, nearly all image acquisition has been digital with progressively increasing primary soft copy diagnosis utilized. Nearly four terabytes of data will have been archived in compressed form by the two year anniversary including more than 300,000 Computed Radiography images.

Intelligent prefetch strategies for historical images in a large PACS

One of the primary advantages of a Picture Archive and Communications System is the availability of historical images. The historical images may be prefetched from the archive the night before a patient visit based on a pull list or may be prefetched after the patient has registered for a radiological exam while the exam is being performed. A set of rules has been devised for prefetch of selected images. Further, a Madigan Army Medical Center statistics of the number of images that are prefetched and used with a new exam are examined. Madigan has more than 300,000 historical images on line for an aid in the diagnosis of new exams. The percent of patients with historical exams is examined as a function of the age of the historical exam. The result of the study is a sample of the number of images that will be prefetched and the distribution of the images over image types and time for a large set of exams.

Early evaluation of MDIS workstations at Madigan Army Medical Center

The image viewing workstation is an all-important link in the PACS (Picture Archiving and Communications System) chain since it represents the interface between the system and the user. For PACS to function, the working environment and transfer of information to the user must be the same or better than the traditional film-based system. The important characteristics of a workstation from a clinical standpoint are acceptable image quality, rapid response time, a friendly user interface, and a well-integrated, highly-reliable, fault-tolerant system which provides the user ample functions to complete his tasks successfully. Since early 1992, the MDIS (Medical Diagnostic Imaging Support) systems diagnostic and clinical workstations have been installed at Madigan Army Medical Center. Various functionalities and performance characteristics of the MDIS workstations such as image display, response time, database, and ergonomics will be presented. User comments and early experience with the workstations as well as new functionality recommended for the future will be discussed.

Design of a receiver operating characteristic (ROC) study of 10:1 lossy image compression

The digital archiving system at Madigan Army Medical Center (MAMC) uses a 10:1 lossy data compression algorithm for most forms of computed radiography. A systematic study on the potential effect of lossy image compression on patient care has been initiated with a series of studies focused on specific diagnostic tasks. The studies are based upon the receiver operating characteristic (ROC) method of analysis for diagnostic systems. The null hypothesis is that observer performance with approximately 10:1 compressed and decompressed images is not different from using original, uncompressed images for detecting subtle pathologic findings seen on computed radiographs of bone, chest, or abdomen, when viewed on a high-resolution monitor. Our design involves collecting cases from eight pathologic categories. Truth is determined by committee using confirmatory studies performed during routine clinical practice whenever possible. Software has been developed to aid in case collection and to allow reading of the cases for the study using stand-alone Siemens Litebox workstations. Data analysis uses two methods, ROC analysis and free-response ROC (FROC) methods. This study will be one of the largest ROC/FROC studies of its kind and could benefit clinical radiology practice using PACS technology. The study design and results from a pilot FROC study are presented.

MDIS workstation: an update of performance after nearly two years of clinical use

The medical diagnostic imaging support workstation has been in clinical use at selected military medical centers since March 1992. The workstation is a critical component in picture archiving and communications systems representing the interface between the system and the end user. The workstation has undergone several software changes over the last year based on feedback from end users. The present performance of the workstation in terms of image manipulation and navigation, response time, database, and reliability is emphasized. Discussion includes clinical acceptance, lessons learned, and future enhancements.

Distribution of workload over the working day in a PACS

A new radiological exam spawns a collection of image movements in a PACS system. Historical images are fetched, images are moved to workstations for diagnosis, selected images are moved to other workstations for clinicians and for consultations. The distributions of the new images over the working day will establish the image load to which the PACS system must respond. At Madigan Army Medical Center 10.1% of the daily load of images occurs in the busiest hour of the day. Individual days may have an hour that has up to 15% of the average daily load. The PACS system must be able to handle the images that are spawned by the average 10.1% busy hour load with margin to be able to handle a 50% overload with acceptable degradation of the performance of the system.

Significance of the Fuji-computed radiography algorithms on hardcopy images.

The appearance and diagnostic quality of images from Fuji-based computed radiography equipment is dependent upon a series of steps involving both procedural criteria and machine parameters. These steps can be divided into the three general categories of image acquisition, image digitization, and image display. The implementation of an effective quality control program for computed radiography requires an understanding of the interdependence of these three stages of image production, and the development of methods to assess both operator and machine deviations from required performance. Our experience thus far with the implementation of CR in a large scale PACS at 3 medical centers underscores the need for dedicated applications training support, and for a systematic approach to parameter adjustment.

Evaluation of traumatic lateral cervical spine computed radiography images: quality control acceptability of images for clinical diagnosis, hardcopy versus high-resolution monitors

The computed radiography images of 100 randomly selected traumatic cervical spine series were evaluated. The studies were reviewed on the laser printed hardcopy and 2K monitor soft copy images. In addition to the cervical vertebrae, the cervico-thoracic vertebral body interface must be recognized for a lateral c-spine image to be acceptable. The level of visualization of the spine was on average, 1/2 vertebral body better on the monitor than the hardcopy image. In 8% of cases, this improve visualization allowed clearance of the lateral cervical spine thereby expediting patient care in this critical area. This presentation will cover the quality of images and techniques to improve the success rate for clearing the cervical spine.

Clinical Experience with Teleradiology in the U.S. Military

The U.S. military through the Medical Diagnostic Imaging Support (MDIS) system is installing teleradiology at multiple medical treatment facilities throughout the US and abroad. The goals are to improve patient care, maximize limited resources, and realize cost savings. This presentation reviews early experience with clinical use of the MDIS teleradiology configuration. Emphasis is on lessons learned in the areas of image quality, speed of image transmission, communication between sites, and the advantages of the MDIS two-way teleradiology configuration. The data is accumulated from the combined experience of the authors at multiple different sites within the continental US, Hawaii, and Korea.