DICOM; ACR-NEMA; history
There are more than 160,000 dentists licensed in the United States. For the dental patient, the dentist is both radiologist and treating clinician. The American Dental Association (ADA) has been a member of the Digital Imaging and Communication in Medicine (DICOM) Standard Committee since 1996. DICOM v.3 provides image object definitions for digital transmission radiography (Dx) with special categorization for intraoral projections (Io), and it also provides for color photography used in dentistry. Digital dental radiographs include transmission images of the head and jaws, pantomography, tomography and cone-beam computed tomography. In 2000, the ADA resolved to strive for interoperability of digital dental images, using the DICOM Standard as the backbone of the effort. ADA Working Group 12.1 was tasked with development of specifications and also with educating the dental profession concerning digital image interoperability. DICOM-related interoperability demonstrations are now a part of the ADA Annual Congress, in the form of seminar and as a noncommercial exhibit.
Dentistry; DICOM, digital imaging, interoperability; radiology, dental; radiology, oral and maxillofacial
This article demonstrates a gateway system for converting image fusion results to digital imaging and communication in medicine (DICOM) objects. For the purpose of standardization and integration, we have followed the guidelines of the Integrated Healthcare Enterprise technical framework and developed a DICOM gateway. The gateway system combines data from hospital information system, image fusion results, and the information generated itself to constitute new DICOM objects. All the mandatory tags defined in standard DICOM object were generated in the gateway system. The gateway system will generate two series of SOP instances of each PET-MR fusion result; SOP (Service Object Pair) one for the reconstructed magnetic resonance (MR) images and the other for position emission tomography (PET) images. The size, resolution, spatial coordinates, and number of frames are the same in both series of SOP instances. Every new generated MR image exactly fits with one of the reconstructed PET images. Those DICOM images are stored to the picture archiving and communication system (PACS) server by means of standard DICOM protocols. When those images are retrieved and viewed by standard DICOM viewing systems, both images can be viewed at the same anatomy location. This system is useful for precise diagnosis and therapy.
DICOM gateway; image fusion; IHE
Primary reading or further evaluation of diagnostic imaging examination often needs a comparison between the actual findings and the relevant prior images of the same patient or similar radiological data found in other patients. This support is of clinical importance and may have significant effects on physicians’ examination reading efficiency, service-quality, and work satisfaction. We developed a visual query-by-example image database for storing and retrieving chest CT images by means of a visual browser Image Management Environment (IME) and tested its retrieval efficiency. The visual browser IME included four fundamental features (segmentation, indexing, quick load and recall, user-friendly interface) in an integrated graphical environment for a user-friendly image database management. The system was tested on a database of 2000 chest CT images, randomly chosen from the digital archives of our institutions. A sample of eight heterogeneous images were used as queries and, for each of them a team of three expert radiologists selected the most similar images from the database (a set of 15 images containing similar abnormalities in the same position of the query). The sensitivity and the positive predictive factor, both averaged over the 8 test queries and 15 answers, were respectively 0.975 and 0.91 The IME system is currently under evaluation at our institutions as an experimental application. We consider it a useful work-in-progress tool for clinical practice facilitating searches for a variety of radiological tasks.
Database; lung; computed tomography
In recent years, notable progress has been made on standardization of medical image presentations in the definition and implementation of the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF). In parallel, the American Association of Physicists in Medicine (AAPM) Task Group 18 has provided much needed guidelines and tools for visual and quantitative assessment of medical display quality. In spite of these advances, however, there are still notable gaps in the effectiveness of DICOM GSDF to assure consistent and high-quality display of medical images. In additions the degree of correlation between display technical data and diagnostic usability and performance of displays remains unclear. This article proposes three specific steps that DICOM, AAPM, and ACR may collectively take to bridge the gap between technical performance and clinical use: (1) DICOM does not provide means and acceptance criteria to evaluate the conformance of a display device to GSDF or to address other image quality characteristics. DICOM can expand beyond luminance response, extending the measurable, quantifiable elements of TG18 such as reflection and resolution. (2) In a large picture archiving and communication system (PACS) installation, it is critical to continually track the appropriate use and performance of multiple display devices. DICOM may help with this task by adding a Device Service Class to the standard to provide for communication and control of image quality parameters between applications and devices, (3) The question of clinical significance of image quality metrics has rarely been addressed by prior efforts. In cooperation with AAPM, the American College of Radiology (ACR), and the Society for Computer Applications in Radiology (SCAR), DICOM may help to initiate research that will determine the clinical consequence of variations in image quality metrics (eg, GSDF conformance) and to define what constitutes image quality from a diagnostic perspective. Implementation of these three initiatives may further the reach and impact of DICOM toward quality medicine.
Display quality; display performance; display calibration; DICOM; AAPM; luminance response; image quality
Clinical magnetic resonance imaging (MRI) scanners play an important role in the diagnosis of diseases and management of patient treatment. Quality assurance (QA) of the clinical MRI scanners is mandatory to obtain optimal images in a modern hospital. In this report, the phantom test for the American College of Radiology (ACR) MRI accreditation is used as the essential part of the MRI QA protocols. Seven important assessments of MR image quality are included as follows: geometric accuracy, high-contrast resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, and low-contrast object detectability. In addition, signal-to-noise ratio and central frequency are monitored as well. The MRI QA procedures were applied to four clinical MRI scanners in our institute twice within 3 months. According to the QA results, the service engineers were more efficient in solving scanners problems when the ACR phantom test was run.
MRI; quality assurance; ACR; phantom; image quality
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.
Informatics; education; residents
A picture archiving and communication system (PACS) study was recently performed by KLAS, a national market intelligence firm specializing in monitoring and reporting the performance of HealthCare’s Information Technology (HIT) vendors. Fifteen leading PACS vendors are included in the study, which provides a snapshot of today’s market performance through the eyes of both users and vendors. KLAS interviewed clients from more than 275 sites, and the study incorporates the opinions of over 345 PACS imaging managers, medical directors, radiologists, chief information officers (CIO), department directors, and vendor executives. Results indicate that the PACS vendors are performing well and overall rate above the HIT industry norm; the market is growing and products are maturing; lines between PACS and radiology, information systems are merging; survey respondents are focusing more on functionality, price, and technology for selection; and the most common benefit of PACS is the cost savings from film and storage.
KLAS 2003 PACS Vendor Performance Study
A study was carried out to determine whether digitized radiologic images added valuable information to Internet consultations from a remote Pacific Island. Chuuk State Hospital (Federated States of Micronesia) has limited film screen radiology, minimal ultrasound capability, and no radiologist. Providers initiate Web-based referrals for consultation or patient transfer. Digitized images (via low-cost digital camera or flatbed scanner) were uploaded to a Web site. Images were assessed for impact on referral decisions. A radiologist scored image quality and confidence (scale: 1–7). Of 97 referrals with images that were reviewed, 74 (76%) image sets were abnormal, 20 (20%) were normal, and 3 (4%) were indeterminate. Median scores were 4 for image quality and 5 for diagnostic confidence. In most cases with abnormal radiology (52/74, 70%), images were considered valuable. Radiologic images digitized with a low-cost camera or flatbed scanner provided valuable information for decision making in an Internet-based consultation and referral process from a remote, impoverished Pacific Island jurisdiction, despite relatively low image quality.
Telemedicine; teleradiology; internet communications; PACS; image capture.
The Society for Computer Applications in Radiology (SCAR) Transforming the Radiological Interpretation Process (TRIP™) Initiative aims to spearhead research, education, and discovery of innovative solutions to address the problem of information and image data overload. The initiative will foster interdisciplinary research on technological, environmental and human factors to better manage and exploit the massive amounts of data. TRIP™ will focus on the following basic objectives: improving the efficiency of interpretation of large data sets, improving the timeliness and effectiveness of communication, and decreasing medical errors. The ultimate goal of the initiative is to improve the quality and safety of patient care. Interdisciplinary research into several broad areas will be necessary to make progress in managing the ever-increasing volume of data. The six concepts involved are human perception, image processing and computer-aided detection (CAD), visualization, navigation and usability, databases and integration, and evaluation and validation of methods and performance. The result of this transformation will affect several key processes in radiology, including image interpretation; communication of imaging results; workflow and efficiency within the health care enterprise; diagnostic accuracy and a reduction in medical errors; and, ultimately, the overall quality of care.
large data sets, radiological image interpretation paradigm
This Project evaluated a human visual system model (JNDmetrix) based on just noticeable difference (JND) and frequency-channel vision-modeling principles to assess whether a Cathode ray tube (CRT) or a liquid crystal display (LCD) monochrome display monitor would yield better observer performance in radiographic interpretation. Key physical characteristics, such as veiling glare and modulation transfer function (MTF) of the CRT and LCD were measured. Regions of interest from mammographic images with masses of different contrast levels were shown once on each display to six radiologists using a counterbalanced presentation order. The images were analyzed using the JNDmetrix model. Performance as measured by receiver operating characteristic (ROC) analysis was significantly better overall on the LCD display (P = 0.0120). The JNDmetrix model predicted the result (P = 0.0046) and correlation between human and computer observers was high (r2 (quadratic) = 0.997). The results suggest that observer performance with LCD displays is superior to CRT viewing, at least for on-axis viewing.
Vision model; observer performance; digital display
Wavelet transform (WT) is a potential tool for the detection of microcalcifications, an early sign of breast cancer. This article describes the implementation and evaluates the performance of two novel WT-based schemes for the automatic detection of clustered microcalcifications in digitized mammograms. Employing a one-dimensional WT technique that utilizes the pseudo-periodicity property of image sequences, the proposed algorithms achieve high detection efficiency and low processing memory requirements. The detection is achieved from the parent–child relationship between the zero-crossings [Marr-Hildreth (M-H) detector] /local extrema (Canny detector) of the WT coefficients at different levels of decomposition. The detected pixels are weighted before the inverse transform is computed, and they are segmented by simple global gray level thresholding. Both detectors produce 95% detection sensitivity, even though there are more false positives for the M-H detector. The M-H detector preserves the shape information and provides better detection sensitivity for mammograms containing widely distributed calcifications.
DWT; microcalcification detection; edge detection; multiplexed wavelet transform; computer-aided methods for breast cancer detection.
Edge-preserving speckle noise reduction is essential to computer-aided ultrasound image processing and understanding. A new class of genetic-neuro-fuzzy filter is proposed to optimize the trade-off between speckle noise removal and edge preservation. The proposed approach combines the advantages of the fuzzy, neural, and genetic paradigms. Neuro-fuzzy approaches are very promising for nonlinear filtering of noisy images. Fuzzy reasoning embedded into the network structure aims at reducing errors while fine details are being processed. The learning method based on the real-time genetic algorithms (GAs) performs an effective training of the network from a collection of training data and yields satisfactory results after a few generations.
The performance of the proposed filter has been compared with that of the commonly used median and Wiener filters in reducing speckle noises on ultrasound images. We evaluate this filter by passing the filter’s output to the edge detection algorithm and observing its ability to detect edge pixels.
Experimental results show that the proposed genetic-neuro-fuzzy technique is very effective in speckle noise reduction as well as detail preserving even in the presence of highly noise corrupted data, and it works significantly better than other well-known conventional methods in the literature.
Ultrasound; speckle; real-time genetic algorithm; neuro-fuzzy; genetic-neuro-fuzzy
Digital imaging systems used in radiology rely on electronic display devices to present images to human observers. Active-matrix liquid crystal displays (AMLCDs) continue to improve and are beginning to be considered for diagnostic image display. In spite of recent progress, AMLCDs are characterized by a change in luminance and contrast response with changes in viewing direction. In this article, we characterize high pixel density AMLCDs (a five-million-pixel monochrome display and a nine-million-pixel color display) in terms of the effect of viewing angle on their luminance and contrast response. We measured angular luminance profiles using a custom-made computer-controlled goniometric instrument and a conoscopic Fourier-optics instrument. We show the angular luminance response as a function of viewing angle, as well as the departure of the measured contrast from the desired response. Our findings indicate small differences between the five-million-pixel (5 MP) and the nine-million-pixel (9 MP) AMLCDs. The 9 MP shows lower variance in contrast with changes in viewing angle, whereas the 5 MP provides a slightly better GSDF compliance for off-normal viewing.
Active-matrix liquid crystal display (AMLCD); viewing angle; gray-scale display function (GSDF)
The efficacy of two medical-grade, self-calibrating, gray scale displays were compared with regard to impact on sensitivity and specificity for the detection of interstitial lung disease (ILD) on computed radiographs (CR). The displays were a 5-megapixel (MP) cathode ray tube (CRT) device and a 3-MP liquid crystal display (LCD). A sample consisting of 230 anteroposterior (AP), posteroanterior (PA), and lateral views of the chest with CT-proven findings characteristic for ILD as well as 80 normal images were compared. This double-blinded trial produced a sample sufficient to detect if the sensitivity of the LCD was 10% or more reduced (one-sided) from the “gold standard” CRT display. Both displays were calibrated to the DICOM gray scale standard and the coefficient of variation of the luminance function varied less than 2% during the study. Five board-certified radiologists specializing in thoracic radiology interpreted the sample on both displays and the intraobserver Az (area under the ROC curve) showed no significant correlation to the display used. In addition, an interobserver kappa analysis showed that the relative disagreement between any observer pair remained relatively constant between displays, and thus was display invariant. This study demonstrated there is no significant change in observer performance sensitivity on 5-MP CRT versus 3-MP LCD displays for CR examinations demonstrating ILD of the chest.
ROC; kappa; image quality; displays; interstitial lung disease; receiver operating characteristic
Most RIS and PACS systems include extensive auditing capabilities as part of their security model, but inspecting those audit logs to obtain useful information can be a daunting task. Manual analysis of audit trails, though cumbersome, is often resorted to because of the difficulty to construct queries to extract complex information from the audit logs. The approach proposed by the authors uses standard off-the-shelf multidimensional analysis software tools to assist the PACS/RIS administrator and/or security officer in analyzing those audit logs to identify and scrutinize suspicious events. Large amounts of data can be quickly reviewed and graphical analysis tools help explore system utilization. While additional efforts are required to fully satisfy the demands of the ever-increasing security and confidentiality pressures, multidimensional analysis tools are a practical step toward actually using the information that is already being captured in the systems’ audit logs. In addition, once the work is performed to capture and manipulate the audit logs into a viable format for the multidimensional analysis tool, it is relatively easy to extend the system to incorporate other pertinent data, thereby enabling the ongoing analysis of other aspects of the department’s workflow.
HIPAA; security; confidentiality; audit logs; multidimensional analysis; OLAP; PACS; picture archiving and communications systems; RIS
With the growing computing capability of mobile phones, a handy mobile controller is developed for accessing the picture archiving and communication system (PACS) to enhance image management for clinicians with nearly no restriction in time and location using various wireless communication modes. The PACS is an integrated system for the distribution and archival of medical images that are acquired by different imaging modalities such as CT (computed tomography) scanners, CR (computed radiography) units, DR (digital radiography) units, US (ultrasonography) scanners, and MR (magnetic resonance) scanners. The mobile controller allows image management of the PACS including display, worklisting, query and retrieval of medical images in DICOM format. In this mobile system, a server program is developed in a PACS Web server which serves as an interface for client programs in the mobile phone and the enterprise PACS for image distribution in hospitals. The application processing is performed on the server side to reduce computational loading in the mobile device. The communication method of mobile phones can be adapted to multiple wireless environments in Hong Kong. This allows greater feasibility to accommodate the rapidly changing communication technology. No complicated computer hardware or software is necessary. Using a mobile phone embedded with the mobile controller client program, this system would serve as a tool for heath care and medical professionals to improve the efficiency of the health care services by speedy delivery of image information. This is particularly important in case of urgent consultation, and it allows health care workers better use of the time for patient care.
Mobile phone; PACS; PDA; filmless; medical images; health care
Serial imaging is frequently performed on patients with diseases of the brain, to track and observe changes. Magnetic resonance imaging provides very detailed and rich information, and is therefore used frequently for this application. The data provided by MR can be so plentiful; however, that it obfuscates the information the radiologist seeks. A system which could reduce the large quantity of primitive data to a smaller and more informative subset of data, emphasizing change, would be useful. This article discusses motivating factors for the production of an automated process to this effect, and reviews the approaches of previous authors. The discussion is focused on brain tumors and multiple sclerosis, but many of the ideas are applicable to other disease processes, as well.
Change detection; magnetic resonance; brain tumor; multiple sclerosis
Integration of a Radiology Information System (RIS) and a Picture Archiving and Communication System (PACS) reduces the risk of inconsistent data by reducing interfaces among databases that contain largely redundant information. Furthermore, RIS/PACS integration is the basis for a filmless radiology facility. Web technology is based on international standards and supplies the main features for the RIS/PACS integration task based on a client/server model. This article presents a web-based system developed to manage and distribute images and diagnostic information within the University Hospital of Ribeirão Preto (HCRP) at the University of São Paulo.
PACS; RIS; filmless radiology; web technology
A multidimensional image navigation and display software was designed for display and interpretation of large sets of multidimensional and multimodality images such as combined PET-CT studies. The software is developed in Objective-C on a Macintosh platform under the MacOS X operating system using the GNUstep development environment. It also benefits from the extremely fast and optimized 3D graphic capabilities of the OpenGL graphic standard widely used for computer games optimized for taking advantage of any hardware graphic accelerator boards available. In the design of the software special attention was given to adapt the user interface to the specific and complex tasks of navigating through large sets of image data. An interactive jog-wheel device widely used in the video and movie industry was implemented to allow users to navigate in the different dimensions of an image set much faster than with a traditional mouse or on-screen cursors and sliders. The program can easily be adapted for very specific tasks that require a limited number of functions, by adding and removing tools from the program’s toolbar and avoiding an overwhelming number of unnecessary tools and functions. The processing and image rendering tools of the software are based on the open-source libraries ITK and VTK. This ensures that all new developments in image processing that could emerge from other academic institutions using these libraries can be directly ported to the OsiriX program. OsiriX is provided free of charge under the GNU open-source licensing agreement at http://homepage.mac.com/rossetantoine/osirix.
DICOM viewer; 3D; image fusion; dynamic series; open-source software
There is continual pressure on the radiology department to increase its productivity. Two important links to productivity in the computed/digital radiography (CR/DR) workflow chain are the postprocessing step by technologists and the primary diagnosis step by radiologists, who may apply additional image enhancements to aid them in diagnosis. With the large matrix size of CR and DR images and the computational complexity of these algorithms, it has been challenging to provide interactive image enhancement, particularly on full-resolution images. We have used a new programmable processor as the main computing engine of enhancement algorithms for CR or DR images. We have mapped these algorithms to the processor, maximally utilizing its architecture. On a 12-bit 2688 × 2688 image, we have achieved the execution time of 465Â ms for adaptive unsharp masking, window/level, image rotate, and lookup table operations using a single processor, which represents at least an order of magnitude improvement compared to the response time of current systems. This kind of performance facilitates rapid computation with preset parameter values and/or enables truly interactive QA processing on radiographs by technologists. The fast response time of these algorithms would be especially useful in a real-time radiology setting, where the radiologist’s waiting time in performing image enhancements before making diagnosis can be greatly reduced. We believe that the use of these processors for fast CR/DR image computing coupled with the seamless flow of images and patient data will enable the radiology department to achieve higher productivity.
Digital radiography; computed radiography; real-time radiology; high-performance computing; workflow; image enhancement; QA processing
The current study is part of a project resulting in a computer-assisted analysis of a hand radiograph yielding an assessment of skeletal maturity. The image analysis is based on features selected from six regions of interest. At various stages of skeletal development different image processing problems have to be addressed. At the early stage, feature extraction is based on Lee filtering followed by the random Gibbs fields and mathematical morphology. Once the fusion starts, wavelet decomposition methods are implemented. The user interface displays the closest neighbors to each image under consideration. Results show the sensitivity of different regions to both stages of development and certain feature sensitivity within each region. At the early stage of development, the distal features are more reliable indicators, whereas at the stage of epiphyseal fusion, a larger dynamic range of middle features makes them more sensitive. In the current study, a graphical user interface has been designed and implemented for testing the image processing routines and comparing the results of quantitative image analysis with the visual interpretation of extracted regions of interest. The user interface may also serve as a teaching tool. At the later stage of the project it will be used as a classification tool.
Skeletal maturity; bone age assessment; computer-aided diagnosis; feature extraction; image analysis; graphical user interface
This article describes an application for capturing, delivering, and tracking urgent radiology exam results. Urgent exam findings are entered using a Web form embedded within the Picture archiving and communication system (PACS) display station. The findings are then accessible via soft copy using the PACS display stations, hospital information system (HIS) terminals, or wireless-enabled personal digital assistants (PDAs) or via hard copy printouts that are generated automatically or on demand. Additionally, quality control is performed on those findings entered by radiology residents and fellows, the results of which are used for both performance tracking and educational activities. The application was developed using Sun Microsystems’ Java programming language. The Java Message Service (JMS) was used to manage the delivery of findings. JMS provides a robust, flexible framework for exchanging messages between disparate applications. The application is now used for all urgent exams; completely replacing the original paper-based system. The use of JMS provides the necessary level of reliability needed by this application.
Integration; Java Message Service (JMS); urgent exams; PACS; clinical information systems; RIS; HIS; PDA