In 2003, the Society for Imaging Informatics in Medicine (SIIM) recognized the problem of rapidly increasing number of images in a radiology study as well as the growing number of studies per patient and the increasing number of patients. This produces a developing issue for radiologists, there was simply no way to efficiently manage the number of images that were produced per day with the available tools. SIIM members organized to help encourage research and development in areas that would transform the radiological interpretation process and trademarked the initiative TRIP™. Since the initiative was started, technology and development has advanced, but has it solved the problem? This paper reviews the literature published in the Journal of Digital Imaging from 2003 until now and analyzes the advances that have been made and what still needs to be done.
Proc. SPIE. 5748, Medical Imaging 2005: PACS and Imaging Informatics
KEYWORDS: Magnetic resonance imaging, Image acquisition, Medical imaging, Computed tomography, Computer networks, Radiology, Viruses, Computer security, Network security, Picture Archiving and Communication System
A Secure Vendor Environment (SVE) was created to protect radiology modalities from network intrusion, worms, viruses, and other forms of damaging attacks. Many vendors do not attempt any form of network security and if an institution demands a non-standard and secure installation, a future system upgrade could and frequently does eliminate any security measures installed during the initial installation. The SVE isolates the vendor equipment behind a virtual firewall on a private network that is invisible to the outside world. All interactions must go though a device containing two network interface cards called an Application Processor that acts as a store-and forward router, performs DICOM repair, proxies modality worklist, and isolates the vendor modalities. A small VPN appliance can open the device temporarily for remote access by vendor engineers. Prior to the routine installation of the SVE, vendor equipment was often attacked by hostile network intruders and viruses or worms, sometimes rendering the equipment unusable until the vendor could reload the system. The resulted in considerable clinical downtime and loss of revenue. Since the relatively low cost SVE solution has routinely been installed with all new equipment, no intrusions have occurred, although our network sniffers and intrusion detectors indicate that we are constantly being scanned for vulnerability.
Purpose: To provide a secure network for vendor equipment in a PACS environment while allowing vendor access for upgrades and system repairs.
Method: The network administrators at our university believe that network security should be implemented at the machine level rather than relying on a firewall. A firewall solution could conceivably block unwanted intrusion from outside the university network, but would still allow literally thousands of potential network users to get through to the PACS network. All the PACS archive, display and routing systems are individually protected from intrusion, but vendors of image producing modalities such as CT, MRI, and CR typically do not protect their equipment from network intrusion. Most vendors use the same user-ids and passwords for their service and administrative accounts which makes it easy for them to get to their systems for remote repairs and upgrades, but also makes it easy for hackers and other unwelcome intruders to gain access.
We use a device with two network interface cards to isolate the vendor network from the main PACS / university / hospital network. This device is a store and forward PACS routing device, a DICOM repair device, a modality worklist proxy device, and a de-facto firewall. This device is named an Application Processor (AP). In addition, a small virtual private network (VPN) device is placed on the system that can be controlled only by the PACS administration. If a vendor engineer needs remote access to upgrade or service the equipment, a temporary connection is enabled for only the computer the engineer is using at the time, then is closed when he/she has completed their work.
Results: The secure vendor environment (SVE) consists of a computer and a VPN appliance and costs approximately $2,000 USD to build. With software, the total system costs approximately $2800 - $3500. The SVE is typically deployed as part of every equipment installation. Since the SVE has been used, we have had no intrusion and no downtime due to hackers, viruses, worms, etc. This is now a part of every project plan for equipment that will become part of the PACS.
New work: The SVE is a unique and new work by our group, developed as a solution totally within our group.
Conclusions: Our results have convinced our administration that this small cost to protect vendor equipment is well worth the investment. Prior to developing this solution, there were numerous occasions where intruders invaded our equipment and rendered it unusable until the software could be reloaded, sometimes resulting in the loss of a day or more of clinical use.
After the events of 9/11, many people questioned their ability to keep critical services operational in the face of massive infrastructure failure. Hospitals increased their backup and recovery power, made plans for emergency water and food, and operated on a heightened alert awareness with more frequent disaster drills. In a film-based radiology department, if a portable X-ray unit, a CT unit, an Ultrasound unit, and an film processor could be operated on emergency power, a limited, but effective number of studies could be performed. However, in a digital department, there is a reliance on the network infrastructure to deliver images to viewing locations. The system developed for our institution uses several imaging PODS, a name we chose because it implied to us a safe, contained environment. Each POD is a stand-alone emergency powered network capable of generating images and displaying them in the POD or printing them to a DICOM printer. The technology we used to create a POD consists of a computer with dual network interface cards joining our private, local POD network, to the hospital network. In the case of an infrastructure failure, each POD can and does work independently to produce CTs, CRs, and Ultrasounds. The system has been tested during disaster drills and works correctly, producing images using equipment technologists are comfortable using with very few emergency switch-over tasks.
Purpose: To provide imaging capabilities in the event of a natural or man-made disaster with infrastructure failure.
Method: After the events of 9/11, many people questioned their ability to keep critical services operational in the face of massive infrastructure failure. Hospitals increased their backup and recovery power, made plans for emergency water and food, and operated on a heightened alert awareness with more frequent disaster drills. In a film-based radiology department, if a portable X-ray unit, a CT unit, an Ultrasound unit, and an film processor could be operated on emergency power, a limited, but effective number of studies could be performed. However, in a digital department, there is a reliance on the network infrastructure to deliver images to viewing locations. The system developed for our institution uses several imaging PODS, a name we chose because it implied to us a safe, contained environment.
Each POD is on both the standard and the emergency power systems. All the vendor equipment that produces images is on a private, stand-alone network controlled either by a simple or a managed switch. Included in each POD is a dry-process DICOM printer that is rarely used during normal operations and a display workstation. One node on the private network is a PACS application processor (AP) with two network interface cards, one for the private network, one for the standard PACS network. During ordinary daily operations, all acquired images pass through this AP and are routed to the PACS archives, web servers, and workstations. However, if the power and network to much of the hospital were to fail, the stand-alone POD could still function. Images are routed to the AP, but cannot forward to the main network. However, they can be routed to the printer and display in the POD. They are also stored on the AP to continue normal routing when the infrastructure is restored.
Results: The imaging PODS have been tested in actual disaster testing where the infrastructure was intentionally removed and worked as designed. To date, we have not had to use them in a real-life scenario and we hope we never do, but we feel we have a reasonable level of emergency imaging capability if we ever need it.
Conclusions: Our testing indicates our PODS are a viable way to continue medical imaging in the face of an emergency with a major part of our network and electrical infrastructure destroyed.
A multi-institutional PACS and electronic radiology practice is in daily operation based at the University of Florida. This system is evolving constantly as technology advances and users become more sophisticated. As the technology advances, however, more things can and do go wrong. The PACS quality control and working groups at the University have compile the problems that have been encountered is this rapidly changing environment and have designed tools or procedures to either eliminate the problems or to minimize their impact on the operation of the system. As a result, a series of automated tools have been created to correct mislabeled images, to monitor the correct operation of the system, and to inform support of problems as soon as they are discovered. In the case where automated tools cannot solve the problem, protocols have been designed and procedures developed to identify issues and resolve them before time is wasted or the system fails. Not every problem can be anticipated and solved prior to it occurring, but this work can help alert new users and perhaps even experienced users to unanticipated disasters with PACS and other technologies associated with an electronic radiology practice.
As the trend toward consolidation of hospitals continues, problems with merging radiology practices multiply. With no standardization of patient identifiers, increased demand for access to reports and medical records, and in some cases, too few radiologists to cover rural areas, the job of creating a unified system for electronic radiology practice becomes an important, frustrating, and time-consuming proposition. After acquiring several rural facilities and a community hospital, researchers and developers at Shands Medical System, Inc, centered at the University of Florida have worked integrate the various systems and create a unified system for image and report dissemination. Digital imaging equipment was installed at each institution and dedicated network lines were installed between rural locations. Since each hospital assigned medical record numbers, an institutional code was added to identify locations of patients and to assure unique identifiers. As radiology information systems (RIS) and hospital information systems (HIS) were implemented, they were interfaced to the PACS and voice recognition systems. A web-server provided wide access to clinical images and an interface to the voice recognition system provided reports when the HIS was not available or had not yet been installed.
When faced with the enormous task of merging several rural and community hospitals with a university hospital, developers were faced with the problem of accessing radiology reports in an electronic radiology practice. Voice recognition systems were installed to handle diagnostic reporting, but not all the facilities had hospital information systems that could receive and disseminate reports. The project goal was to make radiology reports available to clinicians to facilitate treatment and for radiologists to use when comparing previous studies with current ones.
Simulated mass lesions were superimposed onto an anthropomorphic breast phantom and x-rayed using a small field of view digital mammography system. Digital radiographs were acquired at a range of x-ray tube potential (constant detector exposure), and a range of x-ray tube current-time product values (constant x-ray tube potential). Twelve readers assessed the probability of a simulated mass being present in specified regions of interest, with the resultant data used to determine the area under the receiver operating characteristic curve (Az). The mean Az value obtained at 28 kVp/72 mAs was 0.69. At the same x-ray tube potential, the Az score fell to 0.63 (p less than 0.05) at 32 mAs, whereas the mean Az score of 0.71 was not significantly different for the image acquired at 144 mAs. At a constant detector exposure, reducing the x-ray tube potential to 22 kVp (320 mAs) resulted in a mean Az value of 0.72, whereas increasing the x-ray tube potential to 34 kVp (28 mAs) resulted in a mean Az value of 0.69. For the detection of simulated mass lesions in an anthropomorphic breast phantom, changing the kVP at a constant detector exposure had no significant effect on imaging performance, whereas halving the mAs at a constant kVp reduced the Az value by approximately 10%.
Simulated mass lesions, superimposed onto an anthropomorphic breast phantom, were x-rayed using a small field of view digital mammography system. Eight radiologists and four scientists viewed the phantom images on a display monitor in a darkened room. Five readers had prior experience of reading these type of images. Readers assessed the probability of a simulated mass being present in each ROI, with the resultant data used to plot the corresponding Receiver Operating Characteristic (ROC) curves, and determine the corresponding area under the ROC curve (Az). Readers viewed the same set of images five successive times in a single session, and the time taken to read each image was recorded. The average time to complete the study for all twelve observers was 24 minutes (71 seconds/image). Experienced readers were quicker than novices, and radiologists were quicker than the scientists. The average Az value for the twelve readers for this detection task was 0.842 +/- 0.037 with coefficient of variations for individual readers ranging from 2.1% to 7.7%. Differences in imaging performance between the radiologists and scientists were very small. Analysis of the trends in measured imaging performance for each reader viewing successive (repeat) images showed that there was no improvement in imaging performance with increasing experience.
Designing an image archive and retrieval system that supports multiple users with many different requirements and patterns of use without compromising the performance and functionality required by diagnostic radiology is an intellectual and technical challenge. A diagnostic archive, optimized for performance when retrieving diagnostic images for radiologists needed to be expanded to support a growing clinical review network, the University of Florida Brain Institute's demands for neuro-imaging, Biomedical Engineering's imaging sciences, and an electronic teaching file. Each of the groups presented a different set of problems for the designers of the system. In addition, the radiologists did not want to see nay loss of performance as new users were added.
A new dual screen-dual film mammography combination was constructed which made of two phosphor screens and two films loaded into a single x-ray cassette. The screens and films were combined so that a single emulsion film (Film #1, Kodak Min-R E film) was placed in direct contact with the phosphor side of the first screen (Screen #1). Screen #1 was made of the Kodak Min-R phosphor (34.0 mg/cm2 Gd2O2S:Tb) coated on a 4 mil transparent Mylar backing. A double emulsion film (Film #2, Kodak T-Mat G film) was sandwiched between Screen #1 backing and the phosphor side of the second screen (Screen #2). Screen #2 was a Kodak Insight ME screen that has a Gd2O2S:Tb coating weight of 43.1 mg/cm2 and a reflective coating between its phosphor layer and support layer. The relative sensitometric responses and spatial resolution properties of the two films were measured as a function of x-ray tube potential (kVp). A series of a contrast-detail phantom images was obtained by varying the x- ray exposure level at 28 kVp. An observer performance study was subsequently carried out to investigate the low contrast performance using the dual screen-dual film combination. The effective speeds of the two films differed by a factor of 2.12 to 2.67 between 25 to 30 kVp. Film #2 contrast was a factor of two or greater than Film #1 in the range where Film #1 optical density values were under 0.7. Measured MTF curves from digitized edge images showed that Film #1 MTF performance was comparable to a standard Kodak Min-R screen-Min-R E film combination. The limiting spatial resolution was found to be 19.5 lp/mm for Film #1 and approximately 11 lp/mm for Film #2. Observer performance studies showed that the threshold contrast in detecting small (less than 10 mm) breast lesions could be up to a factor of two lower on Film #2 images when regions of interest are underexposed on Film #1 images.
The purpose of this work was to develop a method for systematically testing the reliability of a CR system under realistic daily loads in a non-clinical environment prior to its clinical adoption. Once digital imaging replaces film, it will be very difficult to revert back should the digital system become unreliable. Prior to the beginning of the test, a formal evaluation was performed to set the benchmarks for performance and functionality. A formal protocol was established that included all the 62 imaging plates in the inventory for each 24-hour period in the study. Imaging plates were exposed using different combinations of collimation, orientation, and SID. Anthropomorphic phantoms were used to acquire images of different sizes. Each combination was chosen randomly to simulate the differences that could occur in clinical practice. The tests were performed over a wide range of times with batches of plates processed to simulate the temporal constraints required by the nature of portable radiographs taken in the Intensive Care Unit (ICU). Current patient demographics were used for the test studies so automatic routing algorithms could be tested. During the test, only three minor reliability problems occurred, two of which were not directly related to the CR unit. One plate was discovered to cause a segmentation error that essentially reduced the image to only black and white with no gray levels. This plate was removed from the inventory to be replaced. Another problem was a PACS routing problem that occurred when the DICOM server with which the CR was communicating had a problem with disk space. The final problem was a network printing failure to the laser cameras. Although the units passed the reliability test, problems with interfacing to workstations were discovered. The two issues that were identified were the interpretation of what constitutes a study for CR and the construction of the look-up table for a proper gray scale display.
One side effect of installing a clinical PACS Is that users become dependent upon the technology and in some cases it can be very difficult to revert back to a film based system if components fail. The nature of system failures range from slow deterioration of function as seen in the loss of monitor luminance through sudden catastrophic loss of the entire PACS networks. This paper describes the quality control procedures in place at the University of Florida and the automatic notification system that alerts PACS personnel when a failure has happened or is anticipated. The goal is to recover from a failure with a minimum of downtime and no data loss. Routine quality control is practiced on all aspects of PACS, from acquisition, through network routing, through display, and including archiving. Whenever possible, the system components perform self and between platform checks for active processes, file system status, errors in log files, and system uptime. When an error is detected or a exception occurs, an automatic page is sent to a pager with a diagnostic code. Documentation on each code, trouble shooting procedures, and repairs are kept on an intranet server accessible only to people involved in maintaining the PACS. In addition to the automatic paging system for error conditions, acquisition is assured by an automatic fax report sent on a daily basis to all technologists acquiring PACS images to be used as a cross check that all studies are archived prior to being removed from the acquisition systems. Daily quality control is preformed to assure that studies can be moved from each acquisition and contrast adjustment. The results of selected quality control reports will be presented. The intranet documentation server will be described with the automatic pager system. Monitor quality control reports will be described and the cost of quality control will be quantified. As PACS is accepted as a clinical tool, the same standards of quality control must be established as are expected on other equipment used in the diagnostic process.
The functionality and performance expectations of all PACS components must be specified at the time of purchase and tested completely upon delivery to assure customer satisfaction and successful adoption of the new technology. This process may be more elaborate if the customer agrees to serve as a Beta test site for a new component or a new revision of an existing component.A carefully designed test plan will save time at installation, will allow the customer and vendor to agree on expectations, and will assure that the installation will proceed as planned. This paper describes the test procedure used at the University of Florida to accept each PACS component, either a commercial product, or one developed in house. A set of documents contain descriptions of the pre-installation environment, sets of studies to be used in the test, installation checklist, functional usage reports, subjective evaluations, and problem reporting forms. Training and user documentation is also reviewed and 'help lists' are created to help users perform the most common functions. Although details in the documents are changed to match the type of component being tested, the general form of the test remains the same. A formal procedure for testing the functionality and performance of new equipment can save time for both the vendor and the customer and, if specified at the time of purchase, can serve to document the expectations of the customer. Following these procedures will assure a successful installation and improve customer satisfaction.
Mass lesion detection performance of a LoRAD Digital Spot Mammography (DSM) system was compared with a Kodak Min R screen-film combination exposed either in front of the DSM, or in the Bucky of a GE 600T mammography unit. Low-contrast objects simulating small masses were superimposed on an RMI 165 anthropomorphic breast phantom and radiographs obtained at 28 kVp and an mAs value, which resulted in a mean film density of approximately 1.1. DSM images were obtained at the same radiation exposure as used with screen-film. Fully masked radiographs were viewed on a mammography light box, and the DSM images were viewed on the DSM monitor in a darkened room. Of the 64 regions of interest (ROI) in each type of image, 28 (44%) contained the test object. For each imaging modality, six radiologists and six scientists assessed the probability of a simulated mass being present in each ROI. The resultant data were used to plot receiver operating characteristic (ROC) curves of twelve readers for each of the three imaging modalities investigated. There was no significant difference in reader performance between the screen-film combination exposed in front of the DSM system and exposed in the GE 600T system. Both screen-film imaging systems resulted in the same average area under the ROC curve, Az, of 0.78. At the same level of radiation exposure, the DSM had an average ROC area, Az, of 0.71 which was significantly inferior to the average performance achieved using screen-film (p less than 0.005). For this detection task, there were no significant differences in performance between the radiologists and scientists. Reader performance was found to improve with the number of images read, demonstrating an observer learning curve for this specific detection task.
The purpose of this research and development effort was to solve several image management problems in Picture Archiving and Communications Systems (PACS). First, the patient and study information associated with images was not always correct and only rarely complete. This was due to human error in entering information on a console, and from incomplete data entry forms on image producing equipment. Second, in at least one area, Computed Radiography, the task of data entry was so time consuming that throughput suffered. The third problem was image routing, both within the Department of Radiology and throughout the hospital. The last identified problem was the lack of a common key between the PACS database the Radiology Information System (RIS) database so reports and images could be associated with each other. An RIS/PACS interface was developed in which RIS packets were sent to a PACS process at the time request forms were printed. These packets were parsed to various acquisition computers based on the modality type where they were stored in a MSQL Database for use in validating studies as they were completed prior to being transferred to PACS. DICOM header information from incoming studies were `matched' to a database entry based on the medical record number and modality. Whenever possible, an additional match was made on an accession number stored in the header. A match could result in the DICOM header being completed with detailed information about the patient, patient location, requesting service, and the procedure or study. In the case of the Kodak CR unit, patient and study information were sent directly to the CR workstation where they were accessible using a bar code interface at the time plates were ready to be processed. Routing within the radiology department was determined by comparing the RIS procedure code with an MSQL table to locate the workstation(s) used for viewing this type of study. The data of birth was used to determine whether the study should also be routed to a pediatric workstation. Finally, the accession number as assigned by the RIS was placed in the image header to allow matching of images and reports. The RIS/PACS system now matches patient, study, and other RIS information to PACS images to have improve routing, display, information accuracy, and efficiency. This system was built using a legacy RIS system without an HL7 interface, but the processes were created in a modular fashion that will make them easy to convert to HL7 when an expected new RIS is put in place. In order for a PACS to operate efficiently in an information intensive environment, the data associated with images must be correct, complete, and must contain `hooks' to other information systems in a medical center. The RIS/PACS interface is crucial to a successful PACS implementation.
A large distributed image archive has been designed and is currently in the final stages of development as part of the Picture Archiving and Communications Systems at the University of Florida. The problem was to create a large yet efficient image archive to store the images from all the currently supported imaging modalities with expansion capabilities for the future. The design consists of modality acquisition processors (for the receipt, conversion and routing of image data from the diagnostic imaging equipment), medium term organ based magnetic archives (capable of storing patient studies for 4 - 6 months), a 3 Terabyte mixed media long term archive (currently using Digital Linear Tape), and a centralized image management data base. While the archive was primarily designed to support DICOM, certain legacy image formats such as ACR-NEMA 2.0 and native mode nuclear medicine formats are also supported until DICOM compliant acquisition is available from all imaging modalities.
Proc. SPIE. 2711, Medical Imaging 1996: PACS Design and Evaluation: Engineering and Clinical Issues
KEYWORDS: Human-machine interfaces, Data storage, Diagnostics, Digital imaging, Image transmission, Local area networks, Image storage, Radiology, Teleradiology, Picture Archiving and Communication System
The purpose of this development effort was to evaluate the possibility of using digital technologies to solve image management problems in the Department of Radiology at the University of Florida. The three problem areas investigated were local interpretation of images produced in remote locations, distribution of images to areas outside of radiology, and film handling. In all cases the use of a laser film digitizer interfaced to an existing Picture Archiving and Communication System (PACS) was investigated as a solution to the problem. In each case the volume of studies involved were evaluated to estimate the impact of the solution on the network, archive, and workstations. Communications were stressed in the analysis of the needs for all image transmission. The operational aspects of the solution were examined to determine the needs for training, service, and maintenance. The remote sites requiring local interpretation included were a rural hospital needing coverage for after hours studies, the University of Florida student infirmary, and the emergency room. Distribution of images to the intensive care units was studied to improve image access and patient care. Handling of films originating from remote sites and those requiring urgent reporting were evaluated to improve management functions. The results of our analysis and the decisions that were made based on the analysis are described below. In the cases where systems were installed, a description of the system and its integration into the PACS system is included. For all three problem areas, although we could move images via a digitizer to the archive and a workstation, there was no way to inform the radiologist that a study needed attention. In the case of outside films, the patient did not always have a medical record number that matched one in our Radiology Information Systems (RIS). In order to incorporate all studies for a patient, we needed common locations for orders, reports, and images. RIS orders were generated for each outside study to be interpreted and a medical record number assigned if none existed. All digitized outside films were archived in the PACS archive for later review or comparison use. The request generated by the RIS requesting a diagnostic interpretation was placed at the PACS workstation to alert the radiologists that unread images had arrived and a box was added to the workstation user interface that could be checked by the radiologist to indicate that a report had been dictated. The digitizer system solved several problems, unavailable films in the emergency room, teleradiology, and archiving of outside studies that had been read by University of Florida radiologists. In addition to saving time for outside film management, we now store the studies for comparison purposes, no longer lose emergency room films, generate diagnostic reports on emergency room films in a timely manner (important for billing and reimbursement), and can handle the distributed nature of our business. As changes in health care drive management changes, existing tools can be used in new ways to help make the transition easier. In this case, adding digitizers to an existing PACS network helped solve several image management problems.
Computed radiography (CR) systems transform exposures incident on the imaging plates to image densities using examination specific tonescale display algorithms. A procedure is proposed which permits CR users to optimize these algorithms based on the premise that image contrast should be optimized. This procedure was applied to portable chest x-rays on a medical intensive care unit. Changes made to the display parameters supplied by the manufacturer resulted in an improved quality of the displayed image.
Picture archiving and communication systems (PACS) have been quite successful at the University of Florida in the areas of CT, MR, and nuclear medicine. In each case, although we have not always been able to provide the optimal level of performance, we have been able to solve a problem and the systems are used extensively. Ultrasound images are required in a number of locations and the multiformat camera print capability was no longer adequate for the growing volume in the ultrasound section. Although we were certain we could successfully implement PACS for ultrasound, new forces in health care dictate that we justify our system in terms of cost. We analyzed the feasibility of a PACS solution for ultrasound and designed a system that meets our needs and is cost effective. We evaluated the ultrasound operation in terms of image acquisition patterns and throughput requirements. An inventory of existing and PACS equipment was made to determine the feasibility of interfacing the two systems. Commercial systems were evaluated for functionality and cost and a system was designed to meet our needs. The only way to achieve our goal of installing a cost effective ultrasound PACS was to eliminate film and use the cost savings to offset the cost of new equipment and development. We designed a system that could be produced using inexpensive components and existing hardware and software to meet our needs. A commercial vendor was chosen to provide the ultrasound acquisition. The Radiology Information System interface used at the University provides the necessary data to build a DICOM header, and an existing DICOM server routes the images to the appropriate workstations, archives, and printers. Additional storage is added to an existing archive to accommodate the ultrasound images and two existing workstations are evaluated for use in ultrasound.
Image processing techniques using wavelet signal analysis techniques have shown promise in mammography. Wavelet algorithms are compared with traditional image enhancement techniques of unsharp masking and median filtering. Computer simulated phantom images were generated containing lesions mimicking masses and microcalcifications. The degree of image enhancement was evaluated by comparing processed and original signal-to-noise (SNR) ratios in such phantom images. Results obtained in this study suggest that image processing algorithms based on the wavelet transform are likely to enhance the visibility of low-contrast features in mammograms.
The challenge to archiving images in the modern radiology department arises from the need to interface heterogeneous modalities. The DICOM 3 standard is an industry-wide attempt to produce a homogeneous solution to this problem. Our initial attempt at a unified archive server (Frost et al., 1994) demonstrated that there were limitations imposed by vendor interpretation of the DICOM standard, and initial DICOM toolkit solutions. More rigorous compliance by the vendors to the adopted DICOM standard has allowed the development of a uniform archive server process. As new DICOM conferment equipment is added to the Department of Radiology, the identical archive server process can be utilized, thus significantly reducing the installation, maintenance, and operational costs.
The challenge in providing picture archiving and communication systems (PACS) in the modern managed care environment is to justify its cost, while still providing the required services. The only solution which achieves the economic goal is the elimination of film and its associated costs in favor of PACS. Recognizing that some hardcopy will always be desired, an acceptable inexpensive paper print alternative is required. Our initial networked paper printed solution has replaced all film use in nuclear medicine while still providing economical color and monochrome paper output when required. Extensions of this print architecture for ultrasound, CT and MR are planned for the near future.
A cost effectiveness study on the feasibility of using computed radiography (CR) instead of screen-film methods for portable radiographs indicates that we could only justify CR if film were eliminated. Before purchasing CR equipment, we needed to evaluate the use of softcopy to replace film for routine clinical use. The evaluation had to cover image quality, human factors, and efficiency measures. Screen-film radiographs were digitized and used to simulate CR in two studies. The first study evaluated the quality of digitized images and the workstation user interface. Twenty-one radiographs were selected at random from scopes in the radiology department, were digitized, and transferred to a megascan workstation. Five radiologists were asked to assess the quality of the images and the ease of operation of the workstation while an observer recorded their comments and scores. The second study evaluated the feasibility of using the workstation in a clinical environment. Four radiologists read adult and pediatric portable images in film and softcopy format. Reports were evaluated for differences and timing statistics were kept. The results of the first study indicate that image quality may be acceptable for diagnostic purposes and suggests some changes in the user interface. Newborn infant images were the least acceptable in softcopy, largely due to magnification artifacts introduced when viewing very small images. The evaluation was based on a digitizer as a simulator for a CR unit and the digitizer did not exhibit the same resolution characteristics as CR. Films that were unacceptable from the digitizer are expected to be acceptable with CR. The results of the second study indicated that the high resolution diagnostic workstation could be used in a clinical setting, and that the diagnostic readings were not significantly different between film and softcopy displays. The results also indicated that, depending on the radiologist and the type of images, more time was required to read from the workstation and that the increased time was spent using window/level and magnification/roam functions. This preliminary study suggests that the high resolution workstation developed at the University of Florida has adequate quality and functionality to be used for diagnostic interpretation of portable radiographs if given high resolution images. However, further investigation is indicated before we eliminate film in a CR environment.
At the University of Florida, billing and results reporting are done through the Radiology Information System, and the radiologists needed software to meet the ACR requirements and to keep track of data on needle localizations and implants. Prior to this project all data were kept manually on paper and using various non-integrated software packages.
Proc. SPIE. 2165, Medical Imaging 1994: PACS: Design and Evaluation
KEYWORDS: Sun, Imaging systems, Magnetic resonance imaging, Scanners, Interfaces, Data archive systems, Telecommunications, Computed tomography, Network security, Picture Archiving and Communication System
As part of the Picture Archiving and Communication System effort at the University of Florida, two General Electric high speed advantage CT scanners, a General Electric CT independent review console, a Siemens Magnatom MR imager and a General Electric Signa Advantage MR imager have been connected to a common image archive. Clinical images have been archived from these scanners for about 2 years resulting in about .75 Terabytes of image data. The original archive connections for these scanners were proprietary vendor connections which have recently been replaced by a DICOM implementation utilizing the TCP/IP protocol. A description of the old and new systems will be presented as well as a basic description of the DICOM server which was developed. Timing measurements of the performance of both the old and new interfaces were performed and are presented as well.
Proc. SPIE. 2165, Medical Imaging 1994: PACS: Design and Evaluation
KEYWORDS: Electronics, Medicine, Fiber optics, Buildings, Telecommunications, Optical fiber cables, Local area networks, Data communications, Sports medicine, Picture Archiving and Communication System
A joint project by Shands Hospital, the College of Medicine at the University of Florida, and the Gainesville Regional Utilities (GRU) has produced the design and partial completion of a comprehensive Metropolitan Area Network (MAN). The purpose of this MAN is to supply an integrated medical information network to a number of remote clinical sites both existing and planned. The joint cooperation with GRU will allow the replacement of the current power distribution intercommunications with reliable high speed optical paths.
Proc. SPIE. 2165, Medical Imaging 1994: PACS: Design and Evaluation
KEYWORDS: Human-machine interfaces, Databases, Magnetic resonance imaging, Interfaces, Data acquisition, Computed tomography, Image retrieval, Radiology, Rule based systems, Picture Archiving and Communication System
The University of Florida Medical Center has developed an On-Line Medical Record (OLMR) that serves as a repository of patient information from a number of individual department databases, the Radiology Information System included, and builds a comprehensive electronic patient based chart. The OLMR, widely used by clinicians to view information on test results, will be expanded to add image and graphics display capabilities, and will require pointers to PACS images.
A Du Pont Linx computed radiography (CR) system and associated radiology image viewing station (RIVS) were evaluated with respect to CR image data transfer and image quality performance. Image transfers were compared with conventional film digitizers and CR film processing. Image quality was determined using limiting spatial resolution and low contrast detectability. Processing times differed for CR film output and softcopy display on the RIVS station, ranging between 2 and 10 minutes depending on whether single or batch processing was being used. In general, images from the CR were available on the RIVS display within 100 to 160 seconds compared with a minimum of 270 seconds for producing CR film images. Low contrast detectability performance for CR films was strongly influenced by choice of CR image processing algorithm. In general, there was very little difference between CR film and the corresponding images displayed on a RIVS. Digitization of film and subsequent review on a RIVS, however, generally showed a marked deterioration in low contrast detectability performance.
To make images and data available to all the radiologists, fellows, and residents at the University of Florida an electronic teaching file was required that was accessible to a wide range of people in a number of locations and could display not only data about cases, but the relevant images to go with the case. The multimedia electronic teaching system (METS) uses Oracle as its database management system with addresses of images stored in the tables. To avoid tedious data entry, a connection to the medical center's radiology information system was made. Findings, diagnosis and ACR codes are entered at the data entry screen along with the image numbers of the relevant images for CT, MRI, and US. These images are retrieved from the PACS system for storage on the METS disks. The user interface to the retrieval and display operation allows a search of any or all of the fields in the database through a query by example facility. Simple image manipulation is possible. A Sun workstation was used to implement the system. The user interface was initially written using the MOTIF window manager that could be run over the network on any other Sun workstation. An upgrade uses a MOSAIC with forms to implement data entry and query facilities.
This paper introduces a novel approach for accomplishing mammographic feature analysis through overcomplete multiresolution representations. We show that efficient representations may be identified from digital mammograms and used to enhance features of importance to mammography within a continuum of scale-space. We present a method of contrast enhancement based on an overcomplete, non-separable multiscale representation: the hexagonal wavelet transform. Mammograms are reconstructed from transform coefficients modified at one or more levels by local and global non-linear operators. Multiscale edges identified within distinct levels of transform space provide local support for enhancement. We demonstrate that features extracted from multiresolution representations can provide an adaptive mechanism for accomplishing local contrast enhancement. We suggest that multiscale detection and local enhancement of singularities may be effectively employed for the visualization of breast pathology without excessive noise amplification.
In designing a picture archival and communications network, it is necessary to take into account the specific rates of flow of information from source devices (acquisition nodes) to destination devices (diagnostic workstations and clinical review stations) and to archival storage. It is also important to consider variations in the flow of data throughout the day to build an accurate model of network activity. Studying the distribution of data generated per patient for all imaging modalities in a radiology department permits analysis of the potential impact on the radiology PACS network. The Radiology Department at the University of Florida performs approximately 150,000 examinations per year. In this study, we investigated the pattern of data generation for fifteen acquisition nodes based on all examinations performed by the department for a four week period. For each acquisition node, the number of studies, types of studies, and number of films per study for discrete hours during the day were recorded. The size of these images in MBytes were calculated based on current computed radiography and film scanner technology. These data provide valuable insights into both the image data storage and image data flow bandwidth needs within our Radiology Department. These data are also useful for evaluating the feasibility and limitations of possible PACS network designs.
Researchers around the world are developing computer workstations designed to enable radiologists to display and process radiologic images in a single integrated environment. For the first time in 1992, the RSNA Electronic Communications Committee sponsored an infoRAD Workstation Exhibit at RSNA '92, the scientific assembly and annual meeting of the Radiological Society of North America. The purpose of the exhibit was to demonstrate new developments in workstations to attendees of RSNA '92, to offer hands-on experience with a variety of workstation functionalities and user interfaces, and to provide a hands-on refresher course on workstations. The infoRAD workstation exhibit was a noncommercial, educational exhibit comprised of 12 workstation exhibits designed by university-affiliated researchers. Each exhibitor had the opportunity to lecture about his or her research in one of the theaters set up in the infoRAD exhibit area. A questionnaire was distributed to attendees to assess the value of the workstation exhibits.
A PACS system has been implemented at the University of Florida that has eliminated the use of film in Nuclear Medicine. Six acquisition devices, four display devices, three paper printers, and a digital archive comprise the system. Nuclear Medicine images are viewed on display workstations for diagnosis and are printed in color on paper to be placed in the patient's folder or sent to referring physicians. An interface to the medical center's on-line medical records checks the demographic information stored with the images for accurate spelling of the patient's name, valid patient identification number, and ties the study to the radiology information system order (accession) number. The database used for the on-line medical record and for the Nuclear Medicine PACS system is ORACLE. The archive consists of 4 GBytes of mirrored magnetic disk (essentially 2 GBytes of accessible disk), 8 GBytes of non-mirrored magnetic storage, and a tape jukebox with 50 GByte capacity.
Proc. SPIE. 1899, Medical Imaging 1993: PACS Design and Evaluation
KEYWORDS: Human-machine interfaces, 3D image enhancement, 3D image reconstruction, Image processing, Image enhancement, Image storage, Radiology, Image display, 3D image processing, Picture Archiving and Communication System
Picture archival and communication (PACS) and teleradiology systems require workstations for image display, however not all clinical areas demand the same functionality and performance. Four workstations designed to fill different needs are compared to demonstrate the wide variation in functional requirements. In addition, the results of a survey conducted at InfoRad '92 during the 1992 annual meeting of the Radiological Society of North America are presented demonstrating that more than 90% of the respondents agreed that the two most important features of a workstation are the ability to review multiple studies for a patient at the same time and fast image display.
This paper introduces a novel approach for accomplishing mammographic feature analysis through overcomplete multiresolution representations. We show that efficient representations may be identified from digital mammograms within a continuum of scale space and used to enhance features of importance to mammography. Choosing analyzing functions that are well localized in both space and frequency, results in a powerful methodology for image analysis. We describe methods of contrast enhancement based on two overcomplete (redundant) multiscale representations: (1) Dyadic wavelet transform (2) (phi) -transform. Mammograms are reconstructed from transform coefficients modified at one or more levels by non-linear, logarithmic and constant scale-space weight functions. Multiscale edges identified within distinct levels of transform space provide a local support for enhancement throughout each decomposition. We demonstrate that features extracted from wavelet spaces can provide an adaptive mechanism for accomplishing local contrast enhancement. We suggest that multiscale detection and local enhancement of singularities may be effectively employed for the visualization of breast pathology without excessive noise amplification.
The implementation of Picture Archival and Communication Systems (PACS) within the contemporary radiology department is a complex procedure. Given the complexity of the total PACS environment with its advanced technology requirements, most sites will find it impractical to implement a filmless department with a total PACS solution at this time. Although many technical problems make a total PACS solution impractical in many situations, small, clinically useful, partial PACS (''miniPACS'') can be developed now and can provide experience for future development of more complete PACS. Planning for PACS and creating a supporting infrastructure are important and complex procedures. This paper describes an analysis performed as a neuroradiology PACS system was designed and implemented. Network bandwidth and image storage were evaluated; interfaces were specified; databases were designed; and plans were made to accommodate physical equipment requirements.
PACS research and development efforts at the University of Florida, Department of Radiology have been directed solely toward solving clinical problems with an objective of incorporating successful products or improving the functionality, performance, and reliability of the system. This paper describes the current network and system, experiences with system upgrades and changed, quality control measures used to verify that the system is operational, and current works in progress.
A dial-up, wide bandwidth, digital teleradiology system was implemented between Irwin Army Community Hospital (Fort Riley, Kansas), Munson Army Community Hospital (Fort Leavenworth, Kansas), and the University of Kansas (KU) Medical Center (Kansas City, Kansas). A laser film digitizer and a gray scale display system were used at Irwin and Munson Army Community Hospitals to digitize radiographic films and display digital images. A laser film printer at KU Medical Center generates a film hardcopy of the transmitted digital data and an interactive gray scale display is used to review the digital image data. The communication system consists of dial-up, switched, multiple 56,000 bits per second digital channels, transmitting digital image data in parallel. Conventional radiographic films, multiformat camera films, and laser printed films from multimodality imaging systems-- computed tomography (CT), magnetic resonance (MR), ultrasound (US), nuclear medicine (NM), digital fluorography, and phosphor plate computed radiography (CR)--have been successfully digitized, transmitted, and laser film recorded or gray scale displayed. It is concluded that the implemented dial-up, wide bandwidth, multiple 56,000 bits per second digital teleradiology system provides clinically acceptable image quality reproductions.
Picture archival and communication (PACS) and teleradiology systems require workstations for image display, however not all areas demand the same functionality and performance. A comparison was made between the Vortech Personal Display System (PDS), the Dupont Clinical Review System (CRS), and the dual 2 K X 2.5 K Megascan Diagnostic Workstation (MDW) under development within the department.
The installation of a local area network of microcomputers, workstations, archival storage devices, and digital acquisition modalities is the first step taken by the Radiology Department at the University of Florida toward a comprehensive picture archival and communications system (PACS). The system meets the following requirements, identified during the initial planning and design stage: (1) It allows the connection of heterogeneous equipment from multiple vendors. (2) It is modular and can be extended and modified. (3) It uses current technology with the option to upgrade when improved methodologies are available. (4) It maintains a database of all patient studies/images archived, including those on optical disks not currently mounted in a disk drive. (5) The database can be customized to match specific requirements. (6) ACR-NEMA commands and headers combined with TCP/IP protocols allow access to images by different types of workstations for display and evaluation. In addition to the clinical operation, the network allows communication among microcomputers and research workstations, allowing extended access to images on the archive. The authors discuss their early experience with the system, including design requirements and performance measures.
Teleradiology can be defined as the remote transmission of radiographic images for clinical use or expert interpretation. This definition indicates that there is a physical distance that impedes patient care between the interpreting expert and the primary physician, which can be overcome through electronic communications. The major benefit of such a system is faster communication of images with expert interpretation to remote sites. Depending on the application, teleradiology can extend the usefulness of the radiologist or make the primary physician's job much less time consuming by saving trips to radiology. In addition, patient interaction can be improved by eliminating the interval between the study and the availability of the images and report. It has not been satisfactorily determined that this more rapid system will lead to improved patient care but most students of the current delivery system recognize its limitations and the promise of electronic communications. The authors confine their remarks to the hospital and immediate clinics, leaving the wider area networks to the other presentations in this seminar, and they draw on the experience of the group at the University of Florida in establishing teleradiology to all the intensive care units two years ago and several other more limited, point-to-point electronic communication links. They have, during the past year, worked very hard at establishing several local area networks with digital archiving capability within their institution. This borders on the notion of picture archiving and communication systems (PACS), but has not reached that full potential. The authors find it is useful to concentrate on the teleradiology component because a number of projects can be undertaken without the need of a complete PACS environment. An extensive bibliography, compiled from select sources, is included.