Sheel Kishore

A methodology for the economic assessment of picture archiving and communication systems

Most economic studies of picture archiving and communication systems (PACS) to date, including our own, have focused on the perspectives of the radiology department and its direct costs. However, many researchers have suggested additional cost savings that may accrue to the medical center as a whole through increased operational capacity, fewer lost images, rapid simultaneous access to images, and other decreases in resource utilization. We describe here an economic analysis framework we have developed to estimate these potential additional savings. Our framework is comprised of two parallel measurement methods. The first method estimates the cost of care actually delivered through online capture of charge entries from the hospital’s billing computer and from the clinical practices’ billing database. Multiple regression analyses will be used to model cost of care, length of stay, and other estimates of resource utilization. The second method is the observational measurement of actual resource utilization, such as technologist time, frequency and duration of film searches, and equipment utilization rates. The costs associated with changes in resource use will be estimated using wage rates and other standard economic methods. Our working hypothesis is that after controlling for the underlying clinical and demographic differences among patients, patients imaged using a PACS will have shorter lengths of stay, shorter exam performance times, and decreased costs of care. We expect the results of our analysis to explain and resolve some of the conflicting views of the cost-effectiveness of PACS.

Assessing the impact of PACS on patient care in a medical intensive care unit

In this paper we have present data from pilot studies to estimate the impact on patient care of an intensive care unit display station. The data were collected during two separate one-month periods in 1992. We compared these two different periods in terms of the relative speeds with which images were first viewed by MICU physicians. First, we found that images for routine chest radiographs (CXRs) are viewed by a greater number of physicians and slightly sooner with the PACS display station operating in the MICU than when it is not. Thus, for routine exams, PACS provide the potential for shortening of time intervals between exam completions and image-based clinical actions. A second finding is that the use of the display station for viewing non-routine CXRs is strongly influenced by the speed with which films are digitized. Hence, if film digitization is not rapid, the presence of a MICU display station is unlikely to contribute to a shortening of time intervals between exam completions and image-based clinical actions. This finding supports the use of computed radiography for CXRs in an intensive care unit.

On-demand retrieval paradigm

The University of Pennsylvania Medical Center has been operating a prototype clinical PACS for a number of years. The details of this implementation have been described elsewhere. Early on in the design phase we realized the need to pre-fetch images on a PACS network and incorporated rule-based pre-fetch mechanisms into our Folder Manager software suite. As our PACS expanded and as the pool of users increased to include MR technologies and researchers in addition to radiologists, the case for an on-demand retrieval mechanism became compelling. The design of such a paradigm posed special problems in that the system had to be robust and user-friendly. This paper discusses the design and implementation of such a system. Usage statistics collected over a one-year period are also presented. The retrieval profile shows certain patterns that can be exploited to improve the design of the PACS.

Prospective comparison of the usage of conventional film and PACS based computed radiography for portable chest x-ray imaging in a medical intensive care unit

The purpose of this study was to compare the efficiency of image delivery, the effectiveness of image information transfer, and the timeliness of clinical actions in a medical intensive care unit (MICU) using either conventional screen-film imaging (SF-HC), computed radiography (CR-HC) or a CR based PACS. When the CR based PACS was in use, images could be viewed in the MICU on digital workstation (CR-WS) or in the radiology department as laser printed hard copy (CR-HC). Data were collected by daily interviews with the house-staff, by monitoring computer log-ons and other time stamped activities, and by observing film viewing times in the radiology department with surveillance cameras. The time at which image information was made available to the MICU physicians was decreased during the CR-PACS period as compared with either the SF-HC periods or the CR-HC periods but the image information was not accessed more quickly by the clinical staff. However, the time required to perform image related clinical actions for pulmonary and pleural problems was decreased when images were viewed on the workstation.

Evaluation of PACS in a medical intensive care unit: the effect of computed radiography

Preliminary data is presented from a prospective study of a Picture Archiving and Communication System (PACS) in a Medical Intensive Care Unit (MICU). These data compare the efficiency of image information communication and utilization when the MICU operates in a conventional manner using standard x-ray film as an image acquisition, storage and display medium and a digital manner when images are acquired by Computed Radiography (CR), transmitted and displayed digitally. The CR images were made available for viewing more quickly than conventional film images due to the increased automation provided by the management system of the PACS. Despite the improvement of the availability of images, the time required for the MICU physicians to utilize the image information did not change.

Digital film library implementation

The Radiology Department at the University of Pennsylvania is in the process of clinically testing its PACS implementation. The PACS implementation has been built around a Vortech Image Archival and Retrieval System (IARS) with a 140-platter optical jukebox. The Vortech IARS provides archival services only. A set of software modules have been developed in-house that allow the system to function as a digital film library. The current implementation allows connectivity to a RIS (DECrad), supports the routing of images to two intensive care units, and allows image acquisition from a Du Pont FD2000 laser scanner and two GE SIGNA MR units. All process-to-process communication follows the ACR/NEMA 2.0 protocol. The proposed folder extensions to ACR/NEMA 2.0 are being utilized for sending information to the display nodes. The system has been running clinically for about three months. Details of the design, implementation, and functionality of the PACS are presented.

PACS modeling and development: requirements versus reality

Institutions involved in the research and development of picture archiving and communication systems (PACS) have formulated numerous models that can be used to design the optimal PACS. The models can be classified into one of three categories: engineering, operational, or cost-effectiveness. This paper concentrates on one result of the engineering models: the need for a large network bandwidth in a clinical PACS. The authors discuss a software solution that they have implemented which can cost-effectively achieve the required bandwidths for the majority of the transactions. The software operates on commercially available hardware. The scenarios under which the implementation may fail are also presented.

Intensive care unit workstation usage: digitized film versus phosphor plate imaging

Image sources for the medical intensive care unit workstation used to view portable chest radiographs include both digitized screen-film images and phosphor plate images. This study compares usage of image manipulation functions when physicians view the images from different sources on the workstation. The authors hypothesize that the improved image-to- image uniformity afforded by phosphor plate radiography reduces the use of some of these functions; in particular, the controls for image brightness and contrast. The automated workstation logs and analysis of the results from digitized film-based and phosphor plate-based study periods show that this hypothesis is supported. Overall, use of all image manipulation functions decreased, but use of brightness/contrast showed the largest decrease, from 24.5% for digitized film to 7.6% for phosphor plate imaging. The overall workstation usage increased for the phosphor plate period, supporting the idea that this decrease in function usage was not the result of overall decrease in workstation use. This paper further describes the comparison of the workstation usage during these two study periods.

PACS software testing

A PACS in clinical use must provide a high degree of reliability in terms of uptime and data integrity. For a number of reasons, this is difficult to achieve. There may exist, on a PACS network, a multitude of imaging and display sub-systems each with its own interface peculiarities and requirements. Because a PACS is usually a multi-vendor system, the interface problems are complex. Furthermore, once a PACS is in clinical use, the nature of the process level interactions are complicated and random. To improve overall system reliability requires not only rigorous component testing but also a complete system evaluation. A testing methodology for the evaluation of a multi-vendor PACS is being developed at our institution. Key features of this methodology include the design of component and system stress tests, and system boundary tests that stimulate the depletion of critical resources. Preliminary results from running such tests at the University of Pennsylvania Medical Center are presented.