AAPM/RSNA Tutorial on Equipment Selection: PACS Equipment Overview

Picture archiving and communication systems: past, present, and future

Picture archiving and communication systems (PACS) that digitally acquire, archive, transmit, and display medical images ultimately enabled the transition from an analog film-based operation to a digital workflow revolutionizing radiology. This article briefly traces early generation systems to present-day PACS, noting challenges along with key technological advances and benefits. Thoughts for future PACS evolution are discussed including the promise of integration of artificial intelligence applications.

Three-Dimensional Adaptive Image Compression Concept for Medical Imaging: Application to Computed Tomography Angiography for Peripheral Arteries

Advances in computed tomography (CT) have resulted in a substantial increase in the size of datasets. We built a new concept of medical image compression that provides the best compromise between compression rate and image quality. The method is based on multiple contexts and regions-of-interest (ROI) defined according to the degree of clinical interest. High priority areas (primary ROIs) are assigned a lossless compression. Other areas (secondary ROIs and background) are compressed with moderate or heavy losses. The method is applied to a whole dataset of CT angiography (CTA) of the lower extremity vasculature. It is compared to standard lossy compression techniques in terms of quantitative and qualitative image quality. It is also compared to standard lossless compression techniques in terms of image size reduction and compression ratio. The proposed compression method met quantitative criteria for high-quality encoding. It obtained the highest qualitative image quality rating score, with a statistically significant difference compared to other methods. The average compressed image size was up to 61% lower compared to standard compression techniques, with a 9:1 compression ratio compared with original non-compressed images. Our new adaptive 3D compression method for CT images can save data storage space while preserving clinically relevant information.

Quantitative Evaluation of PACS Query/Retrieve Capabilities

The PACS (Picture Archiving and Communication System) market is heterogenous with dozens of PACS providers having deployed installations in healthcare facilities. The DICOM® query and retrieve interfaces provided by PACS have multiple variations, related to the implemented SOP (Service Object Pair) Classes, transfer syntaxes, extended negotiations, matching attributes, and matching types. These variations can make integration of a new DICOM® consumer with a PACS complex and time consuming. Even if most of PACS products provide a DICOM® conformance statement with a description of its query/retrieve capabilities, there is no collective analysis describing the various PACS query and retrieve capabilities and variations. Also, application developers and healthcare facilities lack a method to evaluate the PACS capabilities and classify its functionalities. GE designed a method to evaluate the PACS capabilities in terms of query retrieve functionalities. Our aim is to analyze several PACS in test and production environments, using our method to provide the DICOM® object consumers a macroscopic knowledge of query/retrieve capabilities of PACS functionalities and its different variations. Our evaluation can also be used by PACS and VNA (Vendor Neutral Archive) developers to evaluate their query/retrieve capabilities, for quality improvement purpose.

Mastoid, middle ear and inner ear analysis in CT scan - a possible contribution for the identification of remains

Objective

We aimed to evaluate whether the internal structures of the human ear have anatomical characteristics that are sufficiently distinctive to contribute to human identification and use in a forensic context.

Materials and methods

After data anonymisation, a dataset containing temporal bone CT scans of 100 subjects was processed by a radiologist who was not involved in the study. Four reference images were selected for each subject. Of the original sample, 10 examinations were used for visual comparison, case by case, against the dataset of 100 patients. This visual assessment was performed independently by four observers, who evaluated the anatomical agreement using a Likert scale (1–5). Inter-observer agreement, true positive rate, positive predictive value, true negative rate, negative predictive value, false positive rate, false negative rate and positive likelihood ratio (LR+) were evaluated.

Results

Inter-observer agreement obtained an overall Cohen’s Kappa = 99.59%. True positive rate, positive predictive value, true negative rate and negative predictive value were all 100%.

Conclusion

Visual assessment of the mastoid examinations was shown to be a robust and reliable approach to identify unique osseous features and contribute to human identification. The statistical analysis indicates that regardless of the examiner’s background and training, the approach has a high degree of accuracy.

Forecasting the demand for radiology services

Since the demand for health services is the key driver for virtually all of a health care organisation's financial and operational activities, it is imperative that health care managers invest the time and effort to develop appropriate and accessible forecasting models for their facility's services. In this article, we analyse and forecast the demand for radiology services at a large, tertiary hospital in Florida. We demonstrate that a comprehensive and accurate forecasting model can be constructed using well-known statistical techniques. We then use our model to illustrate how to provide decision support for radiology managers with respect to department staffing. The methodology we present is not limited to radiology services and we advocate for more routine and widespread use of demand forecasting throughout the health care delivery system.

An Evaluation Protocol for Picture Archiving and Communication System: a Systematic Review

Introduction:

Picture archiving and communication system (PACS) serves to store, transmit, communicate and manage medical images. A logical evaluation protocol assists to determine whether the system is technically, structurally and operationally fit. The purpose of this systematic review was to propose a logical evaluation protocol for PACS, particularly useful for new hospitals and other healthcare institutions in developing countries.

Methods and Materials:

We systematically reviewed 25 out of 267 full-length articles, published between 2000 and 2017, retrieved from four sources: Science Direct, Scopus, PubMed and Google Scholar. The extracted data were tabulated and reviewed successively by three independent panels of experts that oversaw the design of this study and the process by which the PACS evaluation protocol was systematically developed.

Results:

The outcome data were ranked by expert panels and analyzed statistically, with the reliability established at 0.82 based on the Pearson’s correlation coefficient. The essential components and the best options to establish an optimal PACS were organized under nine main sections: system configuration;system network;data storage; datacompression;image input; image characteristics; image presentation; communication link; and system security, with a total of 20 components, each of which capable of working optimally with one or more program options.

Conclusions:

This systematic review presents an objective protocol that is an ideal tool for the evaluation of new or existing PACS at healthcare institutions, particularly in developing countries. Despite the significant advantages, the protocol may face minor limitations, largely due to lack of appropriate technical resources in various clinical settings and the host countries.

Study of Radiologic Technologists' Perceptions of Picture Archiving and Communication System (PACS) Competence and Educational Issues in Western Australia

Although the implementation of picture archiving and communication system (PACS) could increase productivity of radiology departments, this depends on factors such as the PACS competence of radiologic technologists (RTs). The purpose of this study was to investigate the RTs' perceptions of PACS competence and educational issues in Western Australia (WA). A hardcopy questionnaire was distributed to WA RTs for obtaining their perceptions of PACS competence and educational issues. Descriptive (percentage of frequency, mean and standard deviation) and inferential statistics (t test and analysis of variance) were used to analyze the responses of the multiple choice and five-point scale questions from the returned questionnaires. The questionnaire response rate was 57.7% (173 out of 300). The mean values of all PACS competence questions except questions 2e-g are in the range of 3.9-4.9, i.e., around competent to very competent. Participants indicated they received adequate PACS training (mean 3.8). Statistically significant variables influencing RTs' perceptions of their PACS competence and educational issues including the age (p < 0.01), gender (p < 0.05), years of practice (p < 0.005-0.05), primary duty (p < 0.05), medical imaging qualification (p < 0.001), general computer skills (p < 0.001), and type of PACS education received (p < 0.001-0.05). The WA RTs indicated that they were competent in using the modality workstation, PACS and radiology information system, and received adequate training. However, future PACS education programs should be tailored to different RTs' groups. For example, multiple training modules might be necessary to support the PACS competence development of older RTs and those with lower general computer literacy.

An engineering view on megatrends in radiology: digitization to quantitative tools of medicine

Within six months of the discovery of X-ray in 1895, the technology was used to scan the interior of the human body, paving the way for many innovations in the field of medicine, including an ultrasound device in 1950, a CT scanner in 1972, and MRI in 1980. More recent decades have witnessed developments such as digital imaging using a picture archiving and communication system, computer-aided detection/diagnosis, organ-specific workstations, and molecular, functional, and quantitative imaging. One of the latest technical breakthrough in the field of radiology has been imaging genomics and robotic interventions for biopsy and theragnosis. This review provides an engineering perspective on these developments and several other megatrends in radiology.

PACS bypass: a semi-automated routing solution to enable filmless operations when PACS fails

In the filmless imaging department, an integrated imaging and reporting system is only as strong as its weakest link. An outage or downtime of a key segment, such as the Picture Archive Communications System (PACS), is a significant threat to efficient workflow, quality of image interpretation, ordering clinician's review, and ultimately patient care. A multidisciplinary team (including physicists, technologists, radiologists, operations, and IT) developed a backup system to provide business continuity (i.e., quality control, interpretation, reporting, and clinician access) during an extended outage of the main departmental PACS.

Storage media for computers in radiology

The introduction and wide acceptance of digital technology in medical imaging has resulted in an exponential increase in the amount of data produced by the radiology department. There is an insatiable need for storage space to archive this ever-growing volume of image data. Healthcare facilities should plan the type and size of the storage media that they needed, based not just on the volume of data but also on considerations such as the speed and ease of access, redundancy, security, costs, as well as the longevity of the archival technology. This article reviews the various digital storage media and compares their merits and demerits.

Detection of artificial occlusal caries in a phosphor imaging plate system with two types of LCD monitors versus three different films

The aim of this study was to determine diagnostic performance of a storage phosphor plate system Digora Optime (Soredex, Helsinki, Finland) with two types of LCD monitor in the detection of artificial caries when compared to Ultraspeed (D), Ektaspeed Plus (E), and Insight (F) radiographic films. Seventy extracted human molars-with artificial caries-were radiographed under identical standardized conditions using (1) a storage phosphor plate system Digora (Soredex, Helsinki, Finland), (2) Insight, (3) Ektaspeed Plus, and (4) Ultraspeed (Carestream Health Inc, Rochester, NY). All digital images and radiographs were examined by three observers for the presence or absence of artificial caries using a five-point confidence scale. Digital images were evaluated both on a LCD computer monitor (Philips 170S, Holland) and medical monitor-3 megapixel monochrome display (Me355i2, Totoku, Tokyo)-with brightness and contrast enhancement. Observer responses were evaluated using ROC analysis and other measurements for diagnostic accuracy. Storage phosphor images with medical monitor demonstrated higher mean A (z) values (0.70 +/- 0.08) than digital images with computer monitor and conventional films. Storage phosphor images with medical monitor presented the highest score, 0.97, 0.90, 0.94, for each observer, respectively. Also, true positive observations (0.82) and positive likelihood ratios (2.71) were higher in enhanced storage phosphor images with medical monitor. Caries detection of mechanically created lesions by experienced radiologists is roughly comparable when examining D-speed film images and Digora images on both the computer and medical LCD monitors, and appears to be poorer on E- and F-speed film images.

Sustainable IT budgeting: a method to determine not to exceed values for annual infrastructure purchases

Picture-archiving and communication systems are complex entities, but at core they consist of compute processors that are networked together to store and retrieve objects. Therein lay fundamental aspects of both performance benchmarking and predicting future costs, provided one can accurately predict trends in both exam volumes and sizes. Hence, determining the correct amount of capital to reserve annually for the information technology infrastructure can be a difficult process for the administrator of a medical center. Both exam volumes and sizes tend to increase over time. In addition, users demand more compute-intensive applications and expect exam delivery to the desktop to be ever timelier despite the increase in size. Against this, storage, compute, and networking costs tend to decrease over time for the same performance level. At the end of the day, the question of whether to budget more or less capital for next year's infrastructure is not trivial. This paper develops a methodology that uses current baseline data to predict the "ampleness" of a budget to meet future needs.

The impact of PACS on radiologists' work practice

This paper identifies and analyzes how the implementation and use of picture archiving and communication system impacts radiologists' work practice. The study is longitudinal from 1999 to 2005 and have a qualitative perspective were data were collected by structured interviews in a total of 46. The interviews were transcribed, analyzed, and coded using grounded theory as an organizing principle. In radiologists' work practice, three main categories were defined: professional role, diagnostic practice, and technology in use. The changing trends within the professional role indicated that radiologists moved from a more individual professional expertise to become more of an actor in a network. The diagnostic practice changed, as reading x-ray films was seen as an art form in 1999, requiring years of training. Once everyone could view digital images, including 3-dimensional technology, it was easier for other clinicians to see and interpret the images and the skills become accessible to everyone. The change in technology in use as a result of the shift to digital images led to an increased specialization of the radiologist.

The evolving role of radiologists within the health care system

The traditional view of radiologists as physicians who add value to the health care system solely by generating and interpreting diagnostic images is outdated. Radiologists' roles have expanded to encompass economic gatekeeping, political advocacy, public health delivery, patient safety, quality-of-care improvement, and information technology. It is through these roles that radiologists will continue to find new ways to add value to the health care system.

Influence of liquid crystal display monitors on observer performance for detection of diffuse pulmonary disease on chest radiographs

PURPOSE

The purpose of this study was to assess the influence of liquid crystal display (LCD) monitors on the detectability of diffuse pulmonary diseases depicted on chest radiographs by comparing them with a high-resolution cathode ray tube (CRT) monitor.

MATERIALS AND METHODS

A group of 17 radiologists interpreted 87 soft-copy images on LCD monitors with pixel arrays of 1024 x 1280, 1200 x 1600, 1536 x 2048, and 2048 x 2560 and on a CRT monitor with a pixel array of 2048 x 2560. They were asked to indicate their individual confidence levels regarding the presence of diffuse pulmonary diseases. The luminance distributions of all monitors were adjusted to the same distributions, and the ambient illumination was 200 lux. Observer performance was analyzed in terms of the receiver operating characteristics (ROC).

RESULTS

The average ROC curves for the five monitor types were similar, and there were no statistically reliable effects of the five monitor types on the readers' diagnostic performances (P = 0.7587).

CONCLUSION

The detectability of diffuse pulmonary disease on the LCD monitors with a spatial resolution equal to or higher than a matrix size of 1024 x 1280 was found to be equivalent to that on the high-resolution CRT monitor.

Temporal response of medical liquid crystal displaysa)

Displays based on liquid crystal technology suffer from slow temporal response due to the dynamics of the molecular rearrangement in response to a pixel voltage change. A slow display can affect the visualization by the human observer of subtle contrast in dynamic presentation of volumetric image datasets or real-time image sequences. In this paper, we describe a measurement method for the characterization of the temporal response of medical liquid crystal displays (LCDs). The ratio of luminance difference to noise at the gray levels of concern determines the reliability of measurements. Coefficients of variations are used to represent the measurement reliability. We optimized the repeatability of most response time measurements to less than 10%. However, poor repeatability is encountered for the response of adjacent gray levels. 256 X 255 inter-gray-level transition time matrices were measured for four medical displays and one high-definition TV LCD display. Response times range from below 20 ms to above 150 ms. For each display, response times are not uniformly distributed, with a faster response for large gray-level transitions. Transition times are smaller when the starting gray level is between 10 and 20 for a target between 25 and 150. The difference could be over 100 ms for different transitions within a display. For transitions with poor temporal response, the luminance after 1, 3, and 5 frames reaches only 12, 45, and 75% of the target value, respectively. We also found that LCD response time depends on temperature, with 1 h warm-up reducing the response time by a factor of 2.

Choosing a radiology workstation: technical and clinical considerations

Choosing a workstation for daily use in the interpretation of digital radiologic images can be a daunting task. There are numerous products available on the market, but differentiating among them and deciding on what is best for a particular environment can be confusing and frustrating. There is no "one-size-fits-all" workstation, so users must consider a variety of factors when choosing a workstation. This review summarizes the critical elements in a radiology workstation and the characteristics one should be aware of and look for in the selection of a workstation. Issues pertaining to both hardware and software aspects of medical workstations, including interface design, are reviewed, particularly as they may affect the interpretation process.

The influence of liquid crystal display (LCD) monitors on observer performance for the detection of nodular lesions on chest radiographs

PURPOSE

To access the influence of liquid crystal display (LCD) monitors on the detectability of nodular lesions depicted on chest radiographs by comparing them with a high-resolution cathode ray tube (CRT) monitor.

MATERIAL AND METHODS

Ten radiologists interpreted 247 soft-copy images on LCD monitors with pixel arrays of 1,024x1,280, 1,200x1,600, 1,536x2,048 and 2,048x2,560, and a CRT monitor with a pixel array of 2,048x2,560, and were asked to indicate their individual confidence levels regarding the presence of a nodule. These images were chest radiographs with and without a lung nodule from the "Standard Digital Image Database" created by the Japanese Society of Radiological Technology. The luminance distributions of all monitors were adjusted to the same, and the ambient illumination was 200 lux. Observer performance was analyzed in terms of the receiver-operating characteristics.

RESULTS

No significant statistical differences in nodule detection performance were found among the four LCD monitors and the CRT monitor.

CONCLUSION

The nodule detection performance on the LCD monitors with a spatial resolution higher than a matrix size of 1,024x1,280 was found to be equivalent to that on the high-resolution CRT monitor.

Department of Defense picture archiving and communication system acceptance testing: results and identification of problem components

The PACS implementation process is complicated requiring a tremendous amount of time, resources, and planning. The Department of Defense (DOD) has significant experience in developing and refining PACS acceptance testing (AT) protocols that assure contract compliance, clinical safety, and functionality. The DOD's AT experience under the initial Medical Diagnostic Imaging Support System contract led to the current Digital Imaging Network-Picture Archiving and Communications Systems (DIN-PACS) contract AT protocol. To identify the most common system and component deficiencies under the current DIN-PACS AT protocol, 14 tri-service sites were evaluated during 1998-2000. Sixteen system deficiency citations with 154 separate types of limitations were noted with problems involving the workstation, interfaces, and the Radiology Information System comprising more than 50% of the citations. Larger PACS deployments were associated with a higher number of deficiencies. The most commonly cited systems deficiencies were among the most expensive components of the PACS.

Use of a wireless local area network in an orthodontic clinic

Radiographic images and other patient records, including medical histories, demographics, and health insurance information, can now be stored digitally and accessed via patient management programs. However, digital image acquisition and diagnosis and treatment planning are independent tasks, and each is time consuming, especially when performed at different computer workstations. Networking or linking the computers in an office enhances access to imaging and treatment planning tools. Access can be further enhanced if the entire network is wireless. Thanks to wireless technology, stand-alone, desk-bound personal computers have been replaced with mobile, hand-held devices that can communicate with each other and the rest of the world via the Internet. As with any emerging technology, some issues should be kept in mind when adapting to the wireless environment. Foremost is network security. Second is the choice of mobile hardware devices that are used by the orthodontist, office staff, and patients. This article details the standards and choices in wireless technology that can be implemented in an orthodontic clinic and suggests how to select suitable mobile hardware for accessing or adding data to a preexisting network. The network security protocols discussed comply with HIPAA regulations and boost the efficiency of a modern orthodontic clinic.

Reviews in radiology informatics: establishing a core informatics curriculum

The advent of digital imaging and information management within the radiology department has prompted the growth of a new radiology subspecialty: Radiology Informatics. With appropriate training, radiologists can become leaders in Medical Informatics and guide the growth of this technology throughout the medical enterprise. Radiology Informatics fellowships, as well as radiology residency programs, provide inconsistent exposure to all the elements of this subspecialty, in part because of the lack of a common curriculum. The Society for Computer Applications in Radiology (SCAR) has developed a curriculum intended to guide training in Radiology Informatics. This article is the first in a series presented by SCAR and the Journal of Digital Imaging, titled "Reviews in Radiology Informatics." The series is designed to sample from each of the major components in the Radiology Informatics Curriculum, to spark further interest in the field and provide content for informatics education.

Planning for PACS: A comprehensive guide to nontechnical considerations

A complete picture archiving and communication system (PACS) installation is one of the largest projects a radiology department will undertake. Although technology issues are important, they often draw focus away from many other significant issues This paper describes in detail all of these other necessary components that need to be addressed if a PACS installation is to be relatively trouble free, provides guidelines for successful PACS implementation, and details pitfalls to be avoided.

Comparison of liquid crystal versus cathode ray tube display for the detection of simulated chest lesions

The purpose of the study was to compare the detection performance of a cathode ray tube (CRT) monitor versus a liquid crystal display (LCD) monitor for simulated subtle pulmonary lesions. Ten templates containing simulated lung lesions were superimposed on an anthropomorphic chest phantom. Posteroanterior radiographs were obtained using flat panel technology and were displayed on a CRT and an LCD monitor. Image processing and reading conditions were equivalent for both softcopy displays. Five observers assessed lesion detectability using receiver-operating characteristic (ROC) methodology. A multivariate test (Pillai trace) was used to test the significance of differences (P<0.05). The multivariate test revealed significantly different detection rates for the lesion types, but no significant difference between the two display modes. Detection performance for both monitors was higher for nodules and micro-nodules and lower for lines and patchy opacities. Analysis of lesion subgroups according to their location in lucent/obscured lung areas was also not statistically significant. Under ideal reading conditions, CRT and LCD displays perform equivalently for the detection of simulated subtle pulmonary lesions.

AAPM/RSNA Tutorial on Equipment Selection: PACS Equipment Overview

Display systems are key components of the digital radiology department. Current display systems for medical imaging are based on cathode-ray tubes (CRTs) or active-matrix liquid crystal displays (AMLCDs). The CRT is a cathodoluminescent display: Light is generated by exciting a luminescent material with energetic electrons. AMLCDs are light-modulating devices that form the image in the screen by controlling the transparency of individual display pixels. Many image quality aspects of CRTs are determined by the way the pixel luminance is generated in the cathodoluminescent screen. The resolution properties of AMLCDs are much better than those of CRTs. In CRT devices, phosphor granularity and raster scanning patterns are the main components of spatial noise. In AMLCDs, the most notable feature of the noise characteristic is the subpixel structure of complex pixel designs used in medical displays. The small-spot contrast of CRTs is dominated mainly by veiling glare and reflections of ambient illumination. In addition to display reflectance, the contrast of medical AMLCDs is affected by crosstalk and by variations of the luminance at off-normal viewing angles.