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A recurring source of contention between clinicians and radiologists continues to be examination appropriateness when imaging pregnant patients. With the multitude of references on potential radiation risks to the fetus, radiologists tend to be cautious and hesitant about exposing the fetus to radiation. This tendency is often interpreted by referring physicians as intrusion into and delay in the care of their patients. The risk burden of radiation exposure to the fetus has to be carefully weighed against the benefits of obtaining a critical diagnosis quickly and using a single tailored imaging study. In general, there is lower than expected awareness of radiation risks to the fetus from imaging pregnant patients. Modalities that do not use ionizing radiation, such as ultrasonography and magnetic resonance imaging, should be the preferred examinations for evaluating an acute condition in a pregnant patient. However, no examination should be withheld when an important clinical diagnosis is under consideration. Exposure to ionizing radiation may be unavoidable, but there is no evidence to suggest that the risk to the fetus after a single imaging study and an interventional procedure is significant. All efforts should be made to minimize the exposure, with consideration of the risk versus benefit for a given clinical scenario.

Rationale and Objectives We undertook this study to determine whether differences in detector-lesion distance resulted in appreciable effects on digital magnification mammography performance as measured using the American College of Radiology (ACR) mammography phantom and a line pair test pattern. Materials and Methods Images of the standard 42-mm thick standard ACR mammography phantom with a wax insert on one side containing simulated fibers, calcifications, and masses were obtained on a Senographe Essential digital mammography system with the phantom in upright and inverted positions. The process was repeated with a line pair test pattern for measuring resolution. All images were obtained in contact mode, and with 1.5× and 1.8× magnification, and evaluated on a GE PACS monitor. Results Overall, changing lesion-detector distance using standard versus inverted positioning did not appreciably increase the number of objects seen on the ACR phantom under all modes. No greater than one line pair difference was seen in standard versus inverted positioning. At 1.8× magnification mode, no difference was detected in line pair resolution with a change in positioning. Conclusion Differences in lesion-detector distance as modeled using both the ACR mammography phantom and a line pair test pattern did not make an appreciable difference in digital magnification mammography performance.

The primary goal of this study was to determine the radiation dose received during diagnostic and interventional neuroangiographic procedures in a group of pediatric patients. A second goal was to approximate the total average radiation dose from all angiographic and CT studies that pediatric patients underwent during the study period and to estimate the increased risk of cancer incidence in this patient group.The study subjects were pediatric patients who had undergone one or more neuroangiographic procedures at Harborview Medical Center between December 1, 2004, and April 30, 2008. Recorded radiation doses were converted to entrance skin dose (ESD) and effective dose (ED) to indicate deterministic and stochastic damage, respectively. The Biologic Effects of Ionizing Radiation (BEIR) VII, phase 2, report was used to estimate the expected increased risk of cancer in the study population.For diagnostic and therapeutic procedures, a mean ED of 10.4 and 34.0 mSv per procedure was calculated, respectively. The ESD values proved too low to cause deterministic harm. The estimated number of excess cases of malignancy projected from the total average radiation exposure was 890.6 per 100,000 exposed male children and 1,222.5 per 100,000 exposed females, an overall increase of approximately 1% to the lifetime attributable risk of cancer.Although both angiography and CT have revolutionized the practice of medicine and confer benefits to patients, it is important that we continue to investigate the possible adverse effects of these technologies. Protocols that minimize radiation dose without compromising a study should be implemented.

The educational objectives for this self-assessment module on safe MR practices are for the participant to exercise, self-assess, and improve his or her knowledge of hazards to patients, medical personnel, and others in the MR scanner environment, and to exercise, self-assess, and improve his or her knowledge of safe practices in the operation of MR scanners.

A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO 2 ) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The pO 2 measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O 2 ) which reduces the PFC 19 F T 1 . Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of 19 F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of 19 F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated pO 2 maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat.

Purpose: To determine whether a single dose management system alert threshold will suffice for the 34 abdomen protocols on our institution's CT scanners, or if these alert thresholds should be set per protocol. Parametric statistical analysis is ideally valid only for distributions demonstrating: (1) normality (2) homogeneity of variance (3) interval scale and (4) independence. Dose distributions are notoriously non-normal and thus nonparametric statistical analysis is typically required. Methods: Dose distribution data were collected from a HD750 CT scanner (GE Healthcare) at our institution over the third and fourth quarters of 2015. In total there were 1793 abdomen studies using 34 different protocols. Protocols were selected for statistical analysis (SPSS, IBM Corp.) if the count over the period was ≥ 50 to produce statistically meaningful results. Nine protocols with count ranging from 61-398 were selected. Protocol dose distributions were statistically analyzed to determine: (1) normality – Shapiro-Wilk test (2) homogeneity of variance – Levene Statistic (3) similarity of medians – Median test, and (4) similarity of distribution – Kruskal-Wallis test. Results: For the nine abdomen protocols used with exam count ≥ 50, the dose distributions were statistically significantly different from normal for eight protocols (p≤[0.001-0.035]), homogeneity of variance invalidated for five protocols (p≤[0.001-0.037]), median values not the same across all protocols (p

Purpose: To characterize changes in radiation dose after introducing a new real-time image processing technology in interventional radiology systems. Methods: Interventional radiology (IR) procedures are increasingly complex, at times requiring substantial time and radiation dose. The risk of inducing tissue reactions as well as long-term stochastic effects such as radiation-induced cancer is not trivial. To reduce this risk, IR systems are increasingly equipped with dose reduction technologies.Recently, ClarityIQ (Philips Healthcare) technology was installed in our existing neuroradiology IR (NIR) and vascular IR (VIR) suites respectively. ClarityIQ includes real-time image processing that reduces noise/artifacts, enhances images, and sharpens edges while also reducing radiation dose rates. We reviewed 412 NIR (175 pre- and 237 post-ClarityIQ) procedures and 329 VIR (156 preand 173 post-ClarityIQ) procedures performed at our institution pre- and post-ClarityIQ implementation. NIR procedures were primarily classified as interventional or diagnostic. VIR procedures included drain port, drain placement, tube change, mesenteric, and implanted venous procedures. Air Kerma (AK in units of mGy) was documented for all the cases using a commercial radiation exposure management system. Results: When considering all NIR procedures, median AK decreased from 1194 mGy to 561 mGy. When considering all VIR procedures, median AK decreased from 49 to 14 mGy. Both NIR and VIR exhibited a decrease in AK exceeding 50% after ClarityIQ implementation, a statistically significant (p

The factors influencing the image fidelity of gray-scale monitors and how they are determined through both physical and psycho-physical measurements are discussed. Estimation techniques for the amount of image data to be displayed, both the daily digital image data volume and the estimation of the number of gray-scale display stations required, are also examined. Gray-scale display station hardware and software designs are presented. It is pointed out that exceptional attention must be paid to the details of workstation design, as this is the sole interface of the radiologist to the resources of the digital image management network. >

Purpose To examine variation in pediatric trauma head CT imaging protocols in Washington state. Methods A web-based survey was sent to trauma-designated hospitals in Washington state. Respondents were queried about pediatric head trauma volumes, type of CT scanners, and technical information about the CT imaging protocols. Variation in pediatric trauma volumes, CT dose reduction strategies, and effective dose by trauma center levels was examined. Mean head effective dose and organ dose for a female baby were estimated. Results We achieved a 76% overall response rate. Of the 2,215 children who received head CT scans, 36.3% (n=805) received head CT imaging at level 4 trauma center facilities, followed by level 1 trauma center (31.4%; n=695), level 3 trauma center (19.7%; n=436), level 2 trauma center (12%; n=267), and Level 5 (0.5%; n=12) facilities. Most responding trauma center facilities (44/47) reported having a pediatric specific imaging head CT protocols. However, compared to levels 1 and 2 trauma centers together, a greater proportion of levels 3, 4 & 5 trauma center facilities collectively lacked dose reduction strategies (0% vs. 25-57%), tended to have higher mAs (169 ± 113 vs. 110 ± 36), and were later adopters of dose reduction strategies on the CT scanners. There was more than a 10-fold variation in estimated median effective dose for a baby within level 4 trauma center facilities (3.5 ± 0.84 mSv, range 0.60 to 9.60 mSv). Discussion There is both within and between trauma center level variation in pediatric head CT imaging protocols and radiation dose in Washington state.

Gray-scale monitors are an essential element of electronic radiology, and their ability to provide images that are perceived to be identical to those available on conventional or laser-printed film is crucial to success of electronic radiology. Image fidelity is measured in physical characteristics (luminance, dynamic range, distortion, resolution, and noise) and with psychophysical techniques, including receiver operator characteristics analysis with clinical images and testing with contrast-detail patterns to determine threshold contrast. Currently, laser-printed images facilitate greater information transfer than does a gray-scale monitor because of their higher absolute luminance (500 ft-L vs 60 ft-L), greater perceived dynamic range, and better spatial resolution. In the near future, the developments of gray-scale monitors with 150-200 ft-L luminance, a display standard based on just noticeable differences, and algorithms to improve similarities between gray-scale display images and laser-printed images will help increase the acceptability of monitors as a means to make primary diagnoses.

Teleradiology systems require the use of wide area networks (WANs). Design and implementation of a WAN depend on the number of images to be transmitted, desired digital image throughput (based on signaling rate), and cost of the communications link. Image transmission load must be estimated before the communications link can be selected. Communications links used in WANs include T-1 carrier point-to-point service, digital service (DS)-1 dial-up service, DS-3 point-to-point service, DS-0 dial-up service, digital microwave, fiberoptic local loop carriers, and metropolitan area networks (MANs). Depending on the distance between sites, T-1 service may be less costly than DS-1 service; however, for distances more than 200 miles, DS-1 service can be less expensive and more flexible. Both of these services and DS-0 service have lower signaling rates than DS-3 service, which is the fastest and most expensive link. Microwave and fiberoptic links are less expensive but have distance limitations of 14 and 30 miles, respectively. MANs are still being developed but hold the promise of higher signaling rates at lower costs.

An emerging concept in picture archiving and communication systems (PACS) is the PACS infrastructure. The critical components in this infrastructure are communication systems, cluster controller, database integration, fault-tolerant design, and systems integration software. The architecture of a comprehensive communication system within this infrastructure, which will support a digital-based radiology operation, is described. This communication network consists of a real-time analog video and digital components. The video network utilizes broadband and fiber-optic communication technologies. The digital communication is based on a three-tiered network integrating Ethernet, FDDI, and Ultranet technologies. The digital network uses the standard TCP/IP protocol and has a fault-tolerant design. Both components have been in clinical operation since the summer of 1991. >

PACS (Picture Archiving and Communication Systems) database design requires careful understanding of the data and processing needs of radiologists, referring physicians, radiology staff, administrators, and researchers. Due to access requirements, the physical implementation for the management of small text data sets differs from the implementation strategy for large image data sets (centralized vs. distributed storage strategies). In this paper we discuss the database structure, storage architecture, file placement strategies, and administration considerations of the UCLA PACS.

We have integrated a commercially available microprogrammable state machine (Tecmag PULSkit) for use as a magnetic resonance pulse programmer. Providing the capability for active research environment imaging protocols, it features timing resolution of 100 nsec, ten 16-bit loop counters, and individually addressable look-up tables. This integration involved hardware and software integration with a VAX 11 750 at several levels. Hardware: Each of the three gradient channels employs three digital-to-analog converters (DACs). An 8-bit, 4-quadrant, multiplying DAC generates the gradient waveform shape. A 12-bit DAC generates the multiplying DAC scaling voltage, controlling gradient amplitude and sign. A third 12-bit DAC produces a gradient offset (shim) voltage. An eddy current compensation network is present for each gradient channel. Software: The software design philosophy was to create a flexible interface (interactive window environment), while not constraining complex manipulation of the hardware (direct use of the pulse-sequence compiler primitives and microprogramming). The software levels include (a) pulse-sequence microprogramming, (b) pulse-sequence compiler, (c) interactive parameter specification, and (d) canned pulse-sequence microcode library.

This paper focuses on analysis and development of a single-exposure dual-energy digital radiographic method using computed radiography (Fuji FCR-101 storage phosphor system). A detector sandwich consisting of storage phosphor imaging plates and an interdetector filter is used. The goal of this process is to provide a simple dual-energy method using typical plane-projection radiographic equipment and techniques. This approach exploits the transparency of the storage phosphor plates, using radiographic information that would be otherwise lost, to provide energy selective information essentially as a by-product of the radiographic examination. In order to effectively make use of the large dynamic range of the storage phosphor imaging plates (10,000:1), a computed radiography image reading mode of fixed analog-to-digital converter gain and variable photomultiplier sensitivity provides image data which can be related to relative incident exposure for export to the decomposition algorithm. Scatter rejection requirements necessitated crossed 12:1 grids for a field size of 36 x 36 cm. Optimal technique parameters obtained from computer simulation through minimization of the aluminum and Plexiglas equivalent image uncertainty under conditions of constant absorbed does resulted as: 100 kVp using a 0.15-mm-thick tin (Sn) interdetector filter for the lung field. This yields a surface exposure of 23 mR and a surface absorbed dose of 0.26 mGy for a 23-cm-thick chest. Clinical application in evaluation of the solitary pulmonary nodule is discussed, along with an image set demonstrating this application.

OBJECTIVE. Our objective was to develop a better understanding of the complex interrelationship between image noise, reconstruction slice thickness, and patient radiation dose on a 64-MDCT scanner that uses automated tube current modulation.MATERIALS AND METHODS. We reviewed physics theory and performed phantom dose measurements on a 64-MDCT scanner while altering operator-selectable image noise and reconstruction slice thickness.RESULTS. Using phantom dose measurements to adjust theoretic predictions, we constructed both a spreadsheet and a graph that visually display the interrelationships between operator-selected image noise and reconstruction slice thickness and the resulting patient dose.CONCLUSION. This table and graph may help operators understand the trade-offs when prospectively trying to minimize dose and optimize image noise for selected reconstruction slice thicknesses on this type of 64-MDCT scanner.

OBJECTIVE. A data-mining program extracts computed radiography (CR) sensitivity-number (S-number) information from the PACS at our institution on a monthly basis as an ongoing quality assurance (QA) improvement project. These data are compared with the previous month's data and departmental S-number goals. The results are presented at monthly QA meetings. The S-number trends are then used by technologists to modify radiographic technique charts to reach the departmental S-number target range goals.CONCLUSION. This cyclic QA improvement process shows that mining PACS data can be useful in reducing patient radiation dose and interexamination dose variance.

Computers have greatly facilitated the processing and storage of radiologic information. Manufacturers of radiology information systems (RISs) are gradually incorporating options for interfacing their products with other computers (e.g., hospital information systems). However, a growing need exists to also interface RISs with digital radiologic equipment so that images (e.g., computed radiographs of the chest and skeleton) are automatically labeled with identification data. Such connectivity would eliminate redundant work by technologists, decrease errors in the labeling of images, and increase the consistency of patients' data within a radiology department. Unfortunately, the rapid advances in digital technology, combined with the lack of a well-defined standard for the transfer of demographic information between dissimilar systems, have delayed development of these interfaces. We have developed a widely applicable method to automatically transfer patients' demographic data from an RIS to a commercially available computed radiography system. A personal computer is configured with inexpensive programmable telecommunications software to create an interactive gateway, which eliminates the need for redundant data entry (compared with entering data once on the RIS and again on the stand-alone computed radiography system), and thus also decreases errors in the labeling of images.

In order to make use of the overwhelming amount of clinical text and images and supporting information available for medical clinical practice and research, high level intelligence will be integrated into next-generation PACS in the following areas: computer-based decision support, in the development of intelligent user interfaces, in the federation of heterogeneous medical imaging databases, and for PACS operational improvement. Computer-based decision support will allow the knowledge and reasoning of an expert to be applied to procedure selection and diagnostic reasoning. Intelligent display interfaces will be user and context sensitive, allowing for enhanced utilization, efficiency and interpretation of findings. Integrated medical multimedia databases and the tools necessary to intelligently navigate and search through these databases will allow for improved disease detection, and patient treatment as well as generate substantial new medical knowledge. The intelligent optimization of PACS performance and reliability will allow the effective enterprise-wide management of widely distributed imaging networks.

Future developments in teleradiology hinge on the delivery of real or near real-time images, sometimes across less than optimal bandwidth communication channels. Ultrasound, to achieve its greatest diagnostic value, needs to transmit not just still images but video as well. A significant amount of compression, however, may be required to achieve near real-time video across limited bandwidths. This will inevitably result in degraded video quality. A variety of compression algorithms are in widespread use including H.261, H.323, JPEG (Joint Photographic Experts Group), MPEG (Motion Picture Expert Group) and most recently wavelets. We have developed a suite of tools to evaluate each of these methods, and to identify potential areas where wavelet compression may have an advantage. In this particular study, we compare motion wavelet compression to motion JPEG compression using the standard correlation coefficient and the normalized mean squared error, and found the motion wavelet technique slightly better.

As the transition toward total digital image acquisition continues, radiology is transcending the current standard of two-dimensional (2-D) cross-sectional anatomic imaging to more complex models. Among these are three-dimensional (3-D) anatomic images, constructed either from a synthesis of traditional 2-D data sets, or directly from volumetrically acquired data. However, current trends are moving beyond mere anatomic imaging to include physiological data once mainly obtained via nuclear medicine. Recent magnetic resonance pulse sequences, in addition to Doppler and harmonic ultrasound methods, are providing insight into blood flow, oxygenation, and metabolite concentrations non-invasively. Through image registration techniques, these data (even from differing modalities) are being assembled into 2-D and 3-D "fusion" images that promise to revolutionize diagnosis. Furthermore, with improvements in miniaturization, reliability, speed, built-in intelligence, and ease of use, these new developments are finding their way into use by nonspecialists. For instance, a new hand-held ultrasound unit will likely become a common tool among emergency medical teams, military medical teams, and in NASA's manned space program. Portable computed tomography (CT) scanners are already being used in the operating room. The increasing sophistication of imaging instruments will bring about a complementary increase in ease of use for both scanning and data interpretation, bringing diagnostic imaging and therapeutic capabilities closer to the patient, rather than the converse.

Purpose: Our purpose is to evaluate the effectiveness of our two year physics course in preparing radiology residents for the American Board of Radiology (ABR) diagnostic radiology exam. Methods: We designed a new two-year physics course that integrates radiology clinical content and practice and is primarily based on the AAPM curriculum and RSNA/AAPM physics modules. Biweekly classes focus on relevant concepts from assigned reading and use audience response systems to encourage participation. Teaching efficiency is optimized through lecturer rotations of physicists, radiologists, and guest speakers. An emphasis is placed on clinical relevance by requiring lab work and providing equipment demonstrations. Periodic quiz were given during the course. The course website was also redesigned for usability, and physics review lectures were conducted two weeks before the board exam to refresh key concepts. At the completion of our first two-year course, we conducted a confidential evaluation of the faculty and course. The evaluation assessed metrics such as overall organization, clinical relevance of content, and level of difficulty, with a rating scale from poor to excellent. Results: Our evaluation indicated that the redesigned course provided effective board exam preparation, with most responses between good and excellent. There was some criticism on the coursemore » length and on chronological discontinuity, but the review lectures were appreciated by the residents. All of our residents passed the physics component of the ABR exam with scores exceeding the minimum passing score by a significant margin. Conclusion: The course evaluation and board exam results indicate that our new two-year course format provides valuable board exam preparation. This is possible thanks to the time and effort taken by the physics faculty on ensuring the residents get quality physics education.« less

Purpose: We have implemented a commercially available Radiation Exposure Monitoring System (REMS) to enhance the processes of radiation dose data collection, analysis and alerting developed over the past decade at our sites of practice. REMS allows for consolidation of multiple radiation dose information sources and quicker alerting than previously developed processes. Methods: Thirty-nine x-ray producing imaging modalities were interfaced with the REMS: thirteen computed tomography scanners, sixteen angiography/interventional systems, nine digital radiography systems and one mammography system. A number of methodologies were used to provide dose data to the REMS: Modality Performed Procedure Step (MPPS) messages, DICOM Radiation Dose Structured Reports (RDSR), and DICOM header information. Once interfaced, the dosimetry information from each device underwent validation (first 15–20 exams) before release for viewing by end-users: physicians, medical physicists, technologists and administrators. Results: Before REMS, our diagnostic physics group pulled dosimetry data from seven disparate databases throughout the radiology, radiation oncology, cardiology, electrophysiology, anesthesiology/pain management and vascular surgery departments at two major medical centers and four associated outpatient clinics. With the REMS implementation, we now have one authoritative source of dose information for alerting, longitudinal analysis, dashboard/graphics generation and benchmarking. REMS provides immediate automatic dose alerts utilizing thresholds calculated through dailymore » statistical analysis. This has streamlined our Closing the Loop process for estimated skin exposures in excess of our institutional specific substantial radiation dose level which relied on technologist notification of the diagnostic physics group and daily report from the radiology information system (RIS). REMS also automatically calculates the CT size-specific dose estimate (SSDE) as well as provides two-dimensional angulation dose maps for angiography/interventional procedures. Conclusion: REMS implementation has streamlined and consolidated the dosimetry data collection and analysis process at our institutions while eliminating manual entry error and providing immediate alerting and access to dosimetry data to both physicists and physicians. Brent Stewart has funded research through GE Healthcare.« less

As health care organizations continue on the path toward total digital operations, a topic often raised but not clearly understood is that of computer security. The reason for this is simply the vastness of the topic. Computers and networks are complex, and each service offered is a potential security hole. This article describes for the lay person the fundamental points of computer operation, how these can be points attacked, and how these attacks can be foiled--or at least detected. In addition, a taxonomy that should aid system administrators to evaluate and strengthen their systems is described.

Purpose - A majority of distributed applications in Radiology are being developed and deployed without serious regard to their impact on currently deployed networks or how various network configurations impact end-user response-time. Typically the blame for these delays are directed unthinkingly at the existing network bandwidth. A more thoughtful planning process would consist of analyzing the latency in the various components of the transmission process: the network, computer hardware and computer software processes. We have developed a methodology for the analysis of imaging network workflow, which has been applied to the ultrasound component of the PACS at the University of Washington. Methods - One need not model everything in detail. Precision in simulation modeling is very expensive (time and resources) to obtain, requiring a huge amount of parameters and traffic data. Networks are also inherently chaotic: no two are alike and traffic patterns never repeat themselves exactly, so that even a perfect model will never be precise. The good news is that network capacity is implemented in large quanta (for example, 10, 100 and 1000 Mbps LANs). The important concept for these tools is that time-to-insight is more critical for simulation modeling than aiming for a high degree of precision. The methodology for image network flow analysis consists of: (I) self-discovery of the existing network topology, (2) network traffic profiling with network monitors, (3) automatic model creation from the discovered topology and traffic, and (4) event-driven simulation execution using the generated model from which data for throughput, utilization and latency is obtained. This information is then used to provide estimation of end-user response time for distributed network applications. In addition, as the model definition process is modular and flexible, what if questions such as architecture optimization are evaluated. Results - It was determined from the simulation throughput and utilization results for the ultrasound PACS that the network required reconfiguration of the shared and switched ports as well as reallocation of file transfer pathways. Conclusions - The modeling methodology is not only highly automated, but reduces the time to insight, that time from which one can derive useful decision support information from the modeling process, to a few hours. This methodology has provided valuable information for the reconfiguration of the ultrasound PACS.

Purpose - To integrate multiple DICOM image webservers into the currently existing enterprise-wide web-browsableelectronic medical record (MlNDscape). Over the last six years the University of Washington has created a clinical datarepository combining in a distributed relational database information from multiple departmental databases (MIND). Acharacter cell-based view of this data called the Mini Medical Record (MMR) has been available for four years. MlNDscape,unlike the text-based MMR, provides a platform independent, dynamic, web browser view of the MIND database that can beeasily linked with medical knowledge resources on the network, like PubMed and the Federated Drug Reference. There areover 10,000 MlNDscape user accounts at the University of Washington Academic Medical Centers. The weekday averagenumber of hits to MlNDscape is 35,302 and weekday average number of individual users is 1252. DICOM images frommultiple webservers are now being viewed through the MlNDscape electronic medical record (EMR).Methods

We present a wavelet-based video codec based on a 3-D (x,y,t) wavelet transformer, a uniform quantizer/dequantizer and anarithmetic encoder/decoder. The wavelet transformer uses biorthogonal (9,7) Antonini wavelets in the two spatial dimensionsand Haar wavelets in the time dimension. Multiple levels of decomposition are supported. The codec has been applied to pre-scan-converted (r-theta or poiar coordinate) ultrasound image data and does not produce the type of blocking artifacts thatoccur in MPEG-compressed video. The PSNR (peak signal to noise ratio) at a given compression rate increases with thenumber of levels of decomposition: for our data at 50: 1 compression, the PSNR increases from 1 8.4 dB at one level to 24.0dB at four levels of decomposition. Our 3-D wavelet-based video codec provides the high compression rates required totransmit diagnostic ultrasound video over existing low bandwidth links without introducing the blocking artifacts which havebeen demonstrated to diminish clinical utility.Keywords: Wavelets, video compression, video codec, diagnostic ultrasound

Wavelet compression has been shown to give exceptional subjective image quality with high compression ratios for medical imaging. In an effort to effect real-time wavelet compression of digitized ultrasound video for low bandwidth networks, Fourier domain subsampling may demonstrate reduced computational overhead compared to convolution methods. The anticipated benefit is dependant on: the size of the mother wavelet used, data dimensions along each axis, and available Fourier processing power. The process of wavelet compression is computationally expensive, requiring multiple convolutions with similar mother wavelets at different resolutions. In contrast, Fourier domain subsampling states that if an image is downsampled by a factor of two, the spatial frequencies of the image all increase by a factor of two. This allows the use of only one forward FFT on the data at run time, and only one inverse FFT at the time of each filter application, significantly reducing the computational load. A wavelet transform into the third dimension (time) takes advantage of the high correlation between adjacent frames in ultrasound video. Our presentation will demonstrate a comparison of benchmarks for both wavelet transform methods and analyze the advantage with respect to mother wavelet size.

In the course of evaluating various compression schemes for ultrasound teleradiology applications, itbecame obvious that paper based methods of data collection were ume consuming and error prone. Amethod was sought which allowed participating radiologists to view the ultrasound video clips(compressed to varying degree) at their desks. Furthermore, the method should allow observers to entertheir evaluations and when finished, automatically submit the data to our statistical analysis engine. Wehave found the World Wide Web offered a ready solution. A web page was constructed that contains 18embedded AVI video clips. The 18 clips represent 6 distinct anatomical areas, compressed by variousmethods and amounts, and then randomly distributed through the web page. To the right of each video, aseries of questions are presented which ask the observer to rank (1-5) his/her ability to answerdiagnostically relevant questions. When completed, the observer presses "Submit" and a file of tabdelimited text is created which can then be imported to an Excel workbook. Kappa analysis is thenperformed and the resulting plots demonstrate observer preferences.Keywords: ROC, World Wide Web, Image Analysis

Clinical diagnostic ultrasound (US) is experiencing an expanding role that is well suited to application on the International Space Station (ISS). Diagnostic US can be used to reduce the risks associated with long duration human space flight by providing a non-invasive tool with head-to-toe diagnostic capability in both biomedical research and crew health care. General health care of the astronauts will be diagnosed with US, e.g., kidney stones, gall bladder disease, appendicitis, etc. Initial studies will focus on detection of “ureteral jets” in the bladder. This is a non-invasive test to rule out obstructive uropathy from kidney stones with minimal requirements for crew training. Biomedical research experiments, focusing on the effects of the microgravity environment, will be performed using both the HHU and the HDI 5000. US will be used to evaluate bone density and muscle mass in this environment. Prolonged or emergency EVAs may occur with the ISS. The hand-held ultrasound unit (HHU) and its telemedici...

As radiology departments move closer to enterprise-wide electronic imaging systems, the importance of timely and accurate patient and exam information cannot be overstated. In addition, automated entry of patient and exam information into image acquisition modalities (e.g., computed radiography, CR) enhances technologist productivity, which is critical in high volume practices (e.g. a major trauma center). A difficulty arises, however, since the authoritative source of patient and exam information may be a Radiology Information System (RIS) or a Hospital Information System (HIS) packages its data differently than most imaging modalities. To bridge this gap, we have implemented an interface engine to affect the translation of Health Level Seven (HL7) messages from the RIS (or HIS) into Digital Imaging Communications In Medicine (DICOM) messages for seven CR systems (Fuji Medical Systems, Burbank, CA). Recent measurements suggest that manual technologist transcription of information into the CR unit takes 45.4 plus or minus 3.0 seconds. Since the introduction of the HL7/DICOM broker, the time has dropped to 5.4 plus or minus 0.1 seconds to produce the same information.

Purpose -- To integrate radiological DICOM images into our currently existing web-browsable Electronic Medical Record (MINDscape). Over the last five years the University of Washington has created a clinical data repository combining in a distributed relational database information from multiple departmental databases (MIND). A text-based view of this data called the Mini Medical Record (MMR) has been available for three years. MINDscape, unlike the text based MMR, provides a platform independent, web browser view of the MIND dataset that can easily be linked to other information resources on the network. We have now added the integration of radiological images into MINDscape through a DICOM webserver. Methods/New Work -- we have integrated a commercial webserver that acts as a DICOM Storage Class Provider to our, computed radiography (CR), computed tomography (CT), digital fluoroscopy (DF), magnetic resonance (MR) and ultrasound (US) scanning devices. These images can be accessed through CGI queries or by linking the image server database using ODBC or SQL gateways. This allows the use of dynamic HTML links to the images on the DICOM webserver from MINDscape, so that the radiology reports already resident in the MIND repository can be married with the associated images through the unique examination accession number generated by our Radiology Information System (RIS). The web browser plug-in used provides a wavelet decompression engine (up to 16-bits per pixel) and performs the following image manipulation functions: window/level, flip, invert, sort, rotate, zoom, cine-loop and save as JPEG. Results -- Radiological DICOM image sets (CR, CT, MR and US) are displayed with associated exam reports for referring physician and clinicians anywhere within the widespread academic medical center on PCs, Macs, X-terminals and Unix computers. This system is also being used for home teleradiology application. Conclusion -- Radiological DICOM images can be made available medical center wide to physicians quickly using low-cost and ubiquitous, thin client browsing technology and wavelet compression.

The authors have an in-kind grant from NASA to investigate the application of the Advanced Communications Technology Satellite (ACTS) to teleradiology and telemedicine using the Jet Propulsion Laboratory developed ACTS Mobile Terminal (AMT) uplink. We have recently completed three series of experiments with the ACTS/AMT. Although these experiments were multifaceted, the primary objective was the determination and evaluation of transmitting real- time compressed ultrasound video imagery over the ACTS/AMT satellite link, a primary focus of the author's current ARPA Advanced Biomedical Technology contract. These experiments have demonstrated that real-time compressed ultrasound video imagery can be transmitted over multiple ISDN line bandwidth links with sufficient temporal, contrast and spatial resolution for clinical diagnosis of multiple disease and pathology states to provide subspecialty consultation and education at a distance.