Proceedings Volume 6145

Medical Imaging 2006: PACS and Imaging Informatics

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Proceedings Volume 6145

Medical Imaging 2006: PACS and Imaging Informatics

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Volume Details

Date Published: 2 March 2006
Contents: 9 Sessions, 43 Papers, 0 Presentations
Conference: Medical Imaging 2006
Volume Number: 6145

Table of Contents

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Table of Contents

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  • Display and Interpretation I
  • Display and Interpretation II
  • PACS in Surgery
  • PACS Technology and Architecture
  • Databases and Data Mining
  • Imaging Informatics and Standards
  • Data Management and Security
  • Clinical Applications
  • Poster Session
Display and Interpretation I
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MoniQA: a general approach to monitor quality assurance
J. Jacobs, T. Deprez, G. Marchal M.D., et al.
MoniQA ("Monitor Quality Assurance") is a new, non-commercial, independent quality assurance software application developed in our medical physics team. It is a complete JavaTM - based modular environment for the evaluation of radiological viewing devices and it thus fits in the global quality assurance network of our (film less) radiology department. The purpose of the software tool is to guide the medical physicist through an acceptance protocol and the radiologist through a constancy check protocol by presentation of the necessary test patterns and by automated data collection. Data are then sent to a central management system for further analysis. At the moment more than 55 patterns have been implemented, which can be grouped in schemes to implement protocols (i.e. AAPMtg18, DIN and EUREF). Some test patterns are dynamically created and 'drawn' on the viewing device with random parameters as is the case in a recently proposed new pattern for constancy testing. The software is installed on 35 diagnostic stations (70 monitors) in a film less radiology department. Learning time was very limited. A constancy check -with the new pattern that assesses luminance decrease, resolution problems and geometric distortion- takes only 2 minutes and 28 seconds per monitor. The modular approach of the software allows the evaluation of new or emerging test patterns. We will report on the software and its usability: practicality of the constancy check tests in our hospital and on the results from acceptance tests of viewing stations for digital mammography.
A method for reduction of eye fatigue by optimizing the ambient light conditions in radiology reading rooms
Ambient lighting in soft-copy reading rooms are currently kept at low values to preserve contrast rendition in the dark regions of a medical image. Low illuminance levels, however, create inadequate viewing conditions and may also cause eye-strain. This eye-strain may be attributed to notable variations in luminance adaptation state of the reader's eyes when moving the gaze intermittently between the brighter display and darker surrounding surfaces. This paper presents a methodology to optimize the lighting conditions of reading rooms to reduce visual fatigue by minimizing this variation by exploiting the properties of LCDs with low diffuse reflection coefficients and high luminance ratio. First, a computational model was developed to determine a global luminance adaptation value, Ladp, when viewing a medical image on display. The model is based on the diameter of the pupil size which depends on the luminance of the observed object. Second, this value was compared with the luminance reflected off surrounding surfaces, Ls, under various conditions of room illuminance, E , different values of diffuse reflection coefficients of surrounding surfaces, Rs, and calibration settings of a typical LCD. The results suggest that for typical luminance settings of current LCDs, it is possible to raise ambient illumination to minimize differences in eye adaptation, potentially reducing visual fatigue while also complying with the TG18 specifications for controlled contrast rendition. Specifically, room illumination in the 75-150 lux range and surface diffuse reflection coefficients in the practical range of 0.13-0.22 sr-1 provide an ideal setup for typical LCDs. Furthermore, displays with lower diffuse reflectivity and with higher inherent luminance ratio than currently possible in most LCDs can potentially help further decrease eye fatigue, providing an improved ergonomic viewing conditions in reading rooms.
Display and Interpretation II
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Network-based reading system for lung cancer screening CT
Yuichi Fujino, Kaori Fujimura, Shin-ichiro Nomura, et al.
This research aims to support chest computed tomography (CT) medical checkups to decrease the death rate by lung cancer. We have developed a remote cooperative reading system for lung cancer screening over the Internet, a secure transmission function, and a cooperative reading environment. It is called the Network-based Reading System. A telemedicine system involves many issues, such as network costs and data security if we use it over the Internet, which is an open network. In Japan, broadband access is widespread and its cost is the lowest in the world. We developed our system considering human machine interface and security. It consists of data entry terminals, a database server, a computer aided diagnosis (CAD) system, and some reading terminals. It uses a secure Digital Imaging and Communication in Medicine (DICOM) encrypting method and Public Key Infrastructure (PKI) based secure DICOM image data distribution. We carried out an experimental trial over the Japan Gigabit Network (JGN), which is the testbed for the Japanese next-generation network, and conducted verification experiments of secure screening image distribution, some kinds of data addition, and remote cooperative reading. We found that network bandwidth of about 1.5 Mbps enabled distribution of screening images and cooperative reading and that the encryption and image distribution methods we proposed were applicable to the encryption and distribution of general DICOM images via the Internet.
CMAS: a rich media annotation system for medical imaging
We have developed the CMAS system (Collaborative Medical Annotation System) so that medical professionals will be able to easily annotate digital medical records that contain medical imaging or procedure videos. The CMAS system enables a non-technical person to annotate a medical image or video with their recorded presence. The CMAS system displays medical images via a projector onto a screen; when a doctor (or patient) physically walks in front of this screen with the medical image and gives his/her opinion while gesturing at the image, the CMAS system intuitively captures this interaction by creating a video annotation with HP's Active Shadows technology. The CMAS system automatically transforms physical interactions, ranging from a laser pointer spot to a doctor's physical presence, into video annotation that then can be overlaid on top of the medical image or seamlessly inserted into the procedure video. Annotated in such a manner, the medical record retains the historical development of the diagnostic medical opinion, explained through presence of doctors and their respective annotations. The CMAS system structures the annotation of digital medical records such that image/video annotations from multiple sources, at different times, and from different locations can be maintained within a historical context and be consistently referenced among multiple annotations.
On-demand rendering of an oblique slice through 3D volumetric data using JPEG2000 client-server framework
In medical imaging, the popularity of image capture modalities such as multislice CT and MRI is resulting in an exponential increase in the amount of volumetric data that needs to be archived and transmitted. At the same time, the increased data is taxing the interpretation capabilities of radiologists. One of the workflow strategies recommended for radiologists to overcome the data overload is the use of volumetric navigation. This allows the radiologist to seek a series of oblique slices through the data. However, it might be inconvenient for a radiologist to wait until all the slices are transferred from the PACS server to a client, such as a diagnostic workstation. To overcome this problem, we propose a client-server architecture based on JPEG2000 and JPEG2000 Interactive Protocol (JPIP) for rendering oblique slices through 3D volumetric data stored remotely at a server. The client uses the JPIP protocol for obtaining JPEG2000 compressed data from the server on an as needed basis. In JPEG2000, the image pixels are wavelet-transformed and the wavelet coefficients are grouped into precincts. Based on the positioning of the oblique slice, compressed data from only certain precincts is needed to render the slice. The client communicates this information to the server so that the server can transmit only relevant compressed data. We also discuss the use of caching on the client side for further reduction in bandwidth requirements. Finally, we present simulation results to quantify the bandwidth savings for rendering a series of oblique slices.
PACS in Surgery
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Structured recording of intraoperative surgical workflows
T. Neumuth, N. Durstewitz, M. Fischer, et al.
Surgical Workflows are used for the methodical and scientific analysis of surgical interventions. The approach described here is a step towards developing surgical assist systems based on Surgical Workflows and integrated control systems for the operating room of the future. This paper describes concepts and technologies for the acquisition of Surgical Workflows by monitoring surgical interventions and their presentation. Establishing systems which support the Surgical Workflow in operating rooms requires a multi-staged development process beginning with the description of these workflows. A formalized description of surgical interventions is needed to create a Surgical Workflow. This description can be used to analyze and evaluate surgical interventions in detail. We discuss the subdivision of surgical interventions into work steps regarding different levels of granularity and propose a recording scheme for the acquisition of manual surgical work steps from running interventions. To support the recording process during the intervention, we introduce a new software architecture. Core of the architecture is our Surgical Workflow editor that is intended to deal with the manifold, complex and concurrent relations during an intervention. Furthermore, a method for an automatic generation of graphs is shown which is able to display the recorded surgical work steps of the interventions. Finally we conclude with considerations about extensions of our recording scheme to close the gap to S-PACS systems. The approach was used to record 83 surgical interventions from 6 intervention types from 3 different surgical disciplines: ENT surgery, neurosurgery and interventional radiology. The interventions were recorded at the University Hospital Leipzig, Germany and at the Georgetown University Hospital, Washington, D.C., USA.
Workflow in interventional radiology: nerve blocks and facet blocks
Donald Siddoway, Mary Lou Ingeholm, Oliver Burgert, et al.
Workflow analysis has the potential to dramatically improve the efficiency and clinical outcomes of medical procedures. In this study, we recorded the workflow for nerve block and facet block procedures in the interventional radiology suite at Georgetown University Hospital in Washington, DC, USA. We employed a custom client/server software architecture developed by the Innovation Center for Computer Assisted Surgery (ICCAS) at the University of Leipzig, Germany. This software runs in an internet browser, and allows the user to record the actions taken by the physician during a procedure. The data recorded during the procedure is stored as an XML document, which can then be further processed. We have successfully gathered data on a number if cases using a tablet PC, and these preliminary results show the feasibility of using this software in an interventional radiology setting. We are currently accruing additional cases and when more data has been collected we will analyze the workflow of these procedures to look for inefficiencies and potential improvements.
An ultrasound image-guided surgical workflow model
A 2003 report in the Journal of Annual Surgery predicted an increase in demand for surgical services to be as high as 14 to 47% in the workload of all surgical fields by 2020. Medical difficulties which are already now apparent in the surgical OR (Operation Room) will be amplified in the near future and it is necessary to address this problem and develop strategies to handle the workload. Workflow issues are central to the efficiency of the OR and in response to today's continuing workforce shortages and escalating costs. Among them include: Inefficient and redundant processes, System Inflexibility, Ergonomic deficiencies, Scattered Data, Lack of Guidelines, Standards, and Organization. The objective of this research is to validate the hypothesis that a workflow model does improve the efficiency and quality of surgical procedure. We chose to study the image-guided surgical workflow for US as a first proof of concept by minimizing the OR workflow issues. We developed, and implemented deformable workflow models using existing and projected future clinical environment data as well as a customized ICT system with seamless integration and real-time availability. An ultrasound (US) image-guided surgical workflow (IG SWF) for a specific surgical procedure, the US IG Liver Biopsy, was researched to find out the inefficient and redundant processes, scattered data in clinical systems, and improve the overall quality of surgical procedures to the patient.
PACS Technology and Architecture
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Peer-to-peer architecture for multi-departmental distributed PACS
Antoine Rosset, Joris Heuberger, Lance Pysher, et al.
We have elected to explore peer-to-peer technology as an alternative to centralized PACS architecture for the increasing requirements for wide access to images inside and outside a radiology department. The goal being to allow users across the enterprise to access any study anytime without the need for prefetching or routing of images from central archive. Images can be accessed between different workstations and local storage nodes. We implemented "bonjour" a new remote file access technology developed by Apple allowing applications to share data and files remotely with optimized data access and data transfer. Our Open-source image display platform called OsiriX was adapted to allow sharing of local DICOM images through direct access of each local SQL database to be accessible from any other OsiriX workstation over the network. A server version of Osirix Core Data database also allows to access distributed archives servers in the same way. The infrastructure implemented allows fast and efficient access to any image anywhere anytime independently from the actual physical location of the data. It also allows benefiting from the performance of distributed low-cost and high capacity storage servers that can provide efficient caching of PACS data that was found to be 10 to 20 x faster that accessing the same date from the central PACS archive. It is particularly suitable for large hospitals and academic environments where clinical conferences, interdisciplinary discussions and successive sessions of image processing are often part of complex workflow or patient management and decision making.
A demanding web-based PACS supported by web services technology
Carlos M. A. Costa, Augusto Silva, José L. Oliveira, et al.
During the last years, the ubiquity of web interfaces have pushed practically all PACS suppliers to develop client applications in which clinical practitioners can receive and analyze medical images, using conventional personal computers and Web browsers. However, due to security and performance issues, the utilization of these software packages has been restricted to Intranets. Paradigmatically, one of the most important advantages of digital image systems is to simplify the widespread sharing and remote access of medical data between healthcare institutions. This paper analyses the traditional PACS drawbacks that contribute to their reduced usage in the Internet and describes a PACS based on Web Services technology that supports a customized DICOM encoding syntax and a specific compression scheme providing all historical patient data in a unique Web interface.
A design methodology for fault-tolerance in a DICOM-compliant data storage grid
With the increasing demand of PAC systems, more and more examinations are acquired by healthcare institutions which results in an enormous amount of image data and metadata information that needs to be archived and retrieved especially during disaster recovery. Last year we presented a Data Storage Grid (DSG) architecture based on the five-layer architecture design for Grid technology that provides 99.999% up time. The proposed solution was implemented as a three-site testbed and was developed using Globus 3.2 Toolkit. A grid architecture built on Globus middleware achieves reliability and availability through the distribution of hardware components and services. However, a DICOM-compliant DSG requires a Metadata Catalog to provide the DICOM header information available to DSG clients. For this reason, this paper describes the continued development of the DSG utilizing DICOM and IHE standards including the development of a fault-tolerant Metadata Catalog for a DICOM-compliant data grid environment.
Medical image compression using cubic spline interpolation for low bit-rate telemedicine applications
In this paper, a new medical image compression algorithm using cubic spline interpolation (CSI) is presented for telemedicine applications. The CSI is developed in order to subsample image data with minimal distortion and to achieve image compression. It has been shown in literatures that the CSI can be combined with the JPEG or JPEG2000 algorithm to develop a modified JPEG or JPEG2000 codec, which obtains a higher compression ratio and a better quality of reconstructed image than the standard JPEG and JPEG2000 codecs. This paper further makes use of the modified JPEG codec to medical image compression. Experimental results show that the proposed scheme can increase 25~30% compression ratio of original JPEG medical data compression system with similar visual quality. This system can reduce the loading of telecommunication networks and is quite suitable for low bit-rate telemedicine applications.
Databases and Data Mining
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Atlas of protein expression: image capture, analysis, and design of terabyte image database
Jiahua Wu, Gareth Maslen, Anthony Warford, et al.
The activity of genes in health and disease are manifested through the proteins which they encode. Ultimately, proteins drive functional processes in cells and tissues and so by measuring individual protein levels, studying modifications and discovering their sites of action we will understand better their function. It is possible to visualize the location of proteins of interest in tissue sections using labeled antibodies which bind to the target protein. This procedure, known as immunohistochemistry (IHC), provides valuable information on the cellular and sub-cellular distribution of proteins in tissue. The project, atlas of protein expression, aims to create a quality, information rich database of protein expression profiles, which is accessible to the world-wide research community. For the long term archival value of the data, the accompanying validated antibody and protein clones will potentially have great research, diagnostic and possibly therapeutic potential. To achieve this we had introduced a number of novel technologies, e.g. express recombinant proteins, select antibodies, stain proteins present in tissue section, and tissue microarray (TMA) image analysis. These are currently being optimized, automated and integrated into a multi-disciplinary production process. We had also created infrastructure for multi-terabyte scale image capture, established an image analysis capability for initial screening and quantization.
Relevance feedback for shape-based pathology in spine x-ray image retrieval
Relevance feedback (RF) has become an active research area in Content-based Image Retrieval (CBIR). RF attempts to bridge the gap between low-level image features and high-level human visual perception by analyzing and employing user feedback in an effort to refine the retrieval results to better reflect individual user preference. Need for overcoming this gap is more evident in medical image retrieval due to commonly found characteristics in medical images, viz., (1) images belonging to different pathological categories exhibit subtle differences, and (2) the subjective nature of images often elicits different opinions, even among experts. The National Library of Medicine maintains a collection of digitized spine X-rays from the second National Health and Nutrition Examination Survey (NHANES II). A pathology found frequently in these images is the Anterior Osteophyte (AO), which is of interest to researchers in bone morphometry and osteoarthritis. Since this pathology is manifested as deviation in shape, we have proposed the use of partial shape matching (PSM) methods for pathology-specific spinal X-ray image retrieval. Shape matching tends to suffer from the variability in the pathology expressed by the vertebral shape. This paper describes a novel weight-updating approach to RF. The algorithm was tested and evaluated on a subset of data selected from the image collection. The ground truth was established using Macnab's classification to determine pathology type and a grading system developed by us to express the pathology severity. Experimental results show nearly 20% overall improvement on retrieving the correct pathological category, from 69% without feedback to 88.75% with feedback.
BIRAM: a content-based image retrieval framework for medical images
In the medical field, digital images are becoming more and more important for diagnostics and therapy of the patients. At the same time, the development of new technologies has increased the amount of image data produced in a hospital. This creates a demand for access methods that offer more than text-based queries for retrieval of the information. In this paper is proposed a framework for the retrieval of medical images that allows the use of different algorithms for the search of medical images by similarity. The framework also enables the search for textual information from an associated medical report and DICOM header information. The proposed system can be used for support of clinical decision making and is intended to be integrated with an open source picture, archiving and communication systems (PACS). The BIRAM has the following advantages: (i) Can receive several types of algorithms for image similarity search; (ii) Allows the codification of the report according to a medical dictionary, improving the indexing of the information and retrieval; (iii) The algorithms can be selectively applied to images with the appropriated characteristics, for instance, only in magnetic resonance images. The framework was implemented in Java language using a MS Access 97 database. The proposed framework can still be improved, by the use of regions of interest (ROI), indexing with slim-trees and integration with a PACS Server.
Imaging Informatics and Standards
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Building an IT healthcare enterprise by taking the standards to the limits and sometimes beyond that
Mikael Wintell, Lars Lindsköld, Staffan Gustafsson, et al.
This paper describes a regional approach to build a healthcare infrastructure beginning with radiology for all radiological information from 17 different radiology clinics in different geographic locations throughout the Vastra Gotalands region in the western part of Sweden. The focus will be to use healthcare standards to make this infrastructure work between different vendors of expert system for the healthcare. Many of the standards and initiatives such as IHE, HL7, DICOM, kith-XML, VG-XML and more are providing solution to part or whole of the different needs and possibilities in healthcare today. One of the key things is that this solution also handles the conversion of reports and other applicable data from proprietary RIS format or HL7 2.5 to XML to SR object, which it stores on the large-scale archive provided by the main contractor. The project tries to achieve an IT Healthcare Enterprise based on the IHE approach. The producers of the healthcare information stored in the central archive are forced to follow the information model, created by the region (technical framework), based on the worldwide standards data models DICOM and HL7. Opportunities for changing in work roles and work practices are also mentioned. These changes influence communication, information and work flow and create new possibilities and new risks for the user of this infrastructure.
A unified approach for the adequate visualization of structured medical reports
Jörg Riesmeier, Marco Eichelberg, Thomas Wilkens, et al.
DICOM Structured Reporting (SR) allows for the exchange of structured data and coded information in a standardized way. Although SR documents cannot be viewed directly, the DICOM standard does not specify how an application should render them. As a consequence, the interoperability of SR documents which are intended to be displayed to a medical user is restricted to those structures that are known to the visualizing application. In order to avoid this limitation, we have developed a unified process for the adequate visualization of arbitrary structured medical reports. The basic idea of this new approach is to map well-known sub-structures of the document tree (e. g. templates) to appropriate display components. For this purpose, the generic processing part is strictly separated from an extensible knowledge base which includes a machine-readable description of the template structures and display components. During our work we found out that the template detection is a crucial part of the whole visualization process. On the one hand, the existing template identification method in the DICOM standard covers only a limited number of cases. On the other hand, the complexity and dynamic structure of SR templates make the detection difficult or even impossible in certain cases. Therefore, we propose to enhance this identification method and to revise the corresponding part of the standard. In conclusion, we hope that the presented approach will assist vendors in developing general purpose reporting workstations and thereby promote the use of DICOM Structured Reporting.
IHE cross-enterprise document sharing for imaging: design challenges
Integrating the Healthcare Enterprise (IHE) has recently published a new integration profile for sharing documents between multiple enterprises. The Cross-Enterprise Document Sharing Integration Profile (XDS) lays the basic framework for deploying regional and national Electronic Health Record (EHR). This profile proposes an architecture based on a central Registry that holds metadata information describing published Documents residing in one or multiple Documents Repositories. As medical images constitute important information of the patient health record, it is logical to extend the XDS Integration Profile to include images. However, including images in the EHR presents many challenges. The complete image set is very large; it is useful for radiologists and other specialists such as surgeons and orthopedists. The imaging report, on the other hand, is widely needed and its broad accessibility is vital for achieving optimal patient care. Moreover, a subset of relevant images may also be of wide interest along with the report. Therefore, IHE recently published a new integration profile for sharing images and imaging reports between multiple enterprises. This new profile, the Cross-Enterprise Document Sharing for Imaging (XDS-I), is based on the XDS architecture. The XDS-I integration solution that is published as part of the IHE Technical Framework is the result of an extensive investigation effort of several design solutions. This paper presents and discusses the design challenges and the rationales behind the design decisions of the IHE XDS-I Integration Profile, for a better understanding and appreciation of the final published solution.
Three-dimensional lossless digital signature embedding for the integrity of volumetric images
Zheng Zhou, H. K. Huang, B. J. Liu
Our previous study presented a lossless digital signature embedding (LDSE) method for assuring the integrity of 2D medical images in network transit or during archival. With the advent of multi-detector CT scanners and volume acquisition technologies, a PACS exam can now potentially generate hundreds, even thousands, of images. To perform the 2D LDSE method on each individual image in the volume would be extremely time consuming and inefficient. For this reason, a novel 3D LDSE method has been investigated for 3D image volumes. The method begins with generating a single digital signature (DS) of the entire volume. Embedding of the DS is performed by first identifying a bit stream from the image volume based on the correlation of 3D pixel values. The bit stream is compressed using lossless compression methods and the DS is concatenated with the compressed bit stream. This concatenated bit stream is then embedded within the original image volume. During the verification process, the embedded bit stream is extracted and utilized to recover the original bit stream and the original DS. The original bit stream can be used to restore the image volume which in turn can be used in the verification of the DS. In addition, to 3D LDSE embedding methodology for image volumes, a new procedure is developed to address clinical workflow for 3D image volumes. Experimental results demonstrated that the 3D LDSE method can assure the integrity of 3D image volume efficiently and effectively. In addition, a 3D clinical image workflow procedure was demonstrated.
A DICOM-RT Based ePR radiation therapy information system for decision-support of brain tumor patients
B. J. Liu, M. Law, H. K. Huang, et al.
The need for comprehensive clinical image data and relevant information in image-guided Radiation Therapy (RT) is becoming steadily apparent. Multiple standalone systems utilizing the most technological advancements in imaging, therapeutic radiation, and computerized treatment planning systems acquire key data during the RT treatment course of a patient. One example are patients treated for brain tumors of greater sizes and irregular shapes that utilize state-of-the-art RT technology to deliver pinpoint accurate radiation doses. Various treatment options are available to the patient from Radiation Therapy to Stereotactic Radiosurgery and utilize different RT modalities. The disparate and complex data generated by the RT modalities along with related data scattered throughout the RT department in RT Information/Management systems, Record & Verify systems, and Treatment Planning Systems (TPS) compromise an efficient clinical workflow since the data crucial for a clinical decision may be time-consuming to retrieve, temporarily missing, or even lost. To address these shortcomings, the ACR-NEMA Standards Committee extended its DICOM (Digital Imaging & Communications in Medicine) Standard from Radiology to RT by ratifying seven DICOM RT objects starting in 1997. However, they are rarely used by the RT community in daily clinical operations. In the past, the research focus of an RT department has primarily been developing new protocols and devices to improve treatment process and outcomes of cancer patients with minimal effort dedicated to integration of imaging and information systems. By combining our past experience in medical imaging informatics research, DICOM-RT expertise, and system integration, our research involves using a brain tumor case model to show proof-of-concept that a DICOM-Standard electronic patient record (ePR) system can be developed as a foundation to perform medical imaging informatics research in developing decision-support tools and knowledge base for future data mining applications. As an initial first step, we will develop a methodology to perform medical imaging informatics research on a clinical scenario where brain tumor patients undergo treatment planning for either radiosurgery or radiation therapy. Specifically, we will research the "inverse treatment planning" process that is used for those types of treatments and integrate decision-support knowledge and tools designed to assist in the decision-making process, thus introducing an improved "knowledge-enhanced treatment planning" approach.
Data Management and Security
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A tracking and verification system implemented in a clinical environment for partial HIPAA compliance
The paper describes the methodology for the clinical design and implementation of a Location Tracking and Verification System (LTVS) that has distinct benefits for the Imaging Department at the Healthcare Consultation Center II (HCCII), an outpatient imaging facility located on the USC Health Science Campus. A novel system for tracking and verification of patients and staff in a clinical environment using wireless and facial biometric technology to monitor and automatically identify patients and staff was developed in order to streamline patient workflow, protect against erroneous examinations and create a security zone to prevent and audit unauthorized access to patient healthcare data under the HIPAA mandate. This paper describes the system design and integration methodology based on initial clinical workflow studies within a clinical environment. An outpatient center was chosen as an initial first step for the development and implementation of this system.
Technical experiences of implementing a wireless tracking and facial biometric verification system for a clinical environment
By implementing a tracking and verification system, clinical facilities can effectively monitor workflow and heighten information security in today's growing demand towards digital imaging informatics. This paper presents the technical design and implementation experiences encountered during the development of a Location Tracking and Verification System (LTVS) for a clinical environment. LTVS integrates facial biometrics with wireless tracking so that administrators can manage and monitor patient and staff through a web-based application. Implementation challenges fall into three main areas: 1) Development and Integration, 2) Calibration and Optimization of Wi-Fi Tracking System, and 3) Clinical Implementation. An initial prototype LTVS has been implemented within USC's Healthcare Consultation Center II Outpatient Facility, which currently has a fully digital imaging department environment with integrated HIS/RIS/PACS/VR (Voice Recognition).
Grid based medical image workflow and archiving for research and enterprise PACS applications
Stephan G. Erberich, Manasee Dixit, Vincent Chen, et al.
PACS provides a consistent model to communicate and to store images with recent additions to fault tolerance and disaster reliability. However PACS still lacks fine granulated user based authentication and authorization, flexible data distribution, and semantic associations between images and their embedded information. These are critical components for future Enterprise operations in dynamic medical research and health care environments. Here we introduce a flexible Grid based model of a PACS in order to add these methods and to describe its implementation in the Children's Oncology Group (COG) Grid. The combination of existing standards for medical images, DICOM, and the abstraction to files and meta catalog information in the Grid domain provides new flexibility beyond traditional PACS design. We conclude that Grid technology demonstrates a reliable and efficient distributed informatics infrastructure which is well applicable to medical informatics as described in this work. Grid technology will provide new opportunities for PACS deployment and subsequently new medical image applications.
Hierarchical storage of large volume of multidector CT data using distributed servers
Osman Ratib M.D., Antoine Rosset, Joris Heuberger, et al.
Multidector scanners and hybrid multimodality scanners have the ability to generate large number of high-resolution images resulting in very large data sets. In most cases, these datasets are generated for the sole purpose of generating secondary processed images and 3D rendered images as well as oblique and curved multiplanar reformatted images. It is therefore not essential to archive the original images after they have been processed. We have developed an architecture of distributed archive servers for temporary storage of large image datasets for 3D rendering and image processing without the need for long term storage in PACS archive. With the relatively low cost of storage devices it is possible to configure these servers to hold several months or even years of data, long enough for allowing subsequent re-processing if required by specific clinical situations. We tested the latest generation of RAID servers provided by Apple computers with a capacity of 5 TBytes. We implemented a peer-to-peer data access software based on our Open-Source image management software called OsiriX, allowing remote workstations to directly access DICOM image files located on the server through a new technology called "bonjour". This architecture offers a seamless integration of multiple servers and workstations without the need for central database or complex workflow management tools. It allows efficient access to image data from multiple workstation for image analysis and visualization without the need for image data transfer. It provides a convenient alternative to centralized PACS architecture while avoiding complex and time-consuming data transfer and storage.
Tele diagnostic by web
Because of the development of multimedia technologies like Web and Internet, it now becomes possible to think about Tele Medicine and Tele Diagnostic for a distant place where no doctors and no nurses are situated at or are available. And also some kind of intelligence can be added onto them, which makes possible to give certain kind of medical treatment assistance or suggestions for a patient from a computer diagnostic base through the Internetworking. For doing this, here considers about a basic system of "Tele Diagnostic for a remote place" where it dose not have a doctor and a medical assistance. In order to implement the system, JAVA, VRML, HTML, and CORTONA are used as a basic language and a viewer. And also in order to add a kind of intelligence, Augmented Knowledge In Agent (AKIA) by using Back Propagation Neural Networks (BPNN) is used. And by this study, here can introduce the system that has the following basic mechanisms; By inputting physical data like temperature or blood pressure, the system would show a diagnostic assistance by TEXT. And also the bad place of body would be shown graphically if there were any. The system can be put onto Web, so that anybody could have this assistance at any place ubiquitously only if a person has Internetworking access.
Clinical Applications
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Computer-aided diagnosis workstation and database system for chest diagnosis based on multihelical CT images
Hitoshi Satoh, Noboru Niki, Kiyoshi Mori, et al.
Multi-helical CT scanner advanced remarkably at the speed at which the chest CT images were acquired for mass screening. Mass screening based on multi-helical CT images requires a considerable number of images to be read. It is this time-consuming step that makes the use of helical CT for mass screening impractical at present. To overcome this problem, we have provided diagnostic assistance methods to medical screening specialists by developing a lung cancer screening algorithm that automatically detects suspected lung cancers in helical CT images and a coronary artery calcification screening algorithm that automatically detects suspected coronary artery calcification. We also have developed electronic medical recording system and prototype internet system for the community health in two or more regions by using the Virtual Private Network router and Biometric fingerprint authentication system and Biometric face authentication system for safety of medical information. Based on these diagnostic assistance methods, we have now developed a new computer-aided workstation and database that can display suspected lesions three-dimensionally in a short time. This paper describes basic studies that have been conducted to evaluate this new system. The results of this study indicate that our computer-aided diagnosis workstation and network system can increase diagnostic speed, diagnostic accuracy and safety of medical information.
Carpal bone analysis in bone age assessment
Aifeng Zhang, Arkadiusz Gertych, Sylwia Kurkowska-Pospiech, et al.
A computer-aided-diagnosis (CAD) method has been previously developed in our Laboratory based on features extracted from regions of interest (ROI) in phalanges in a digital hand atlas. Due to various factors, including, the diversity of size, shape and orientation of carpal bones, non-uniformity of soft tissue, low contrast between the bony structure and soft tissue, the automatic identification and segmentation of bone boundaries is an extremely challenging task. Past research work on carpal bone segmentation has been done utilizing dynamic thresholding. However, due to the discrepancy of carpal bones developments and the limitations of segmentation algorithms, carpal bone ROI has not been taken into consideration in the bone age assessment procedure. In this paper, we present a method for fully automatic carpal bone segmentation and feature analysis in hand X-ray radiograph. The purpose of this paper is to automatically segment the carpal bones by anisotropic diffusion and Canny edge detection techniques. By adding their respective features extracted from carpal bones ROI to the phalangeal ROI feature space, the accuracy of bone age assessment can be improved especially when the image processing in the phalangeal ROI fails in younger children.
Using irreversible compression in digital radiology: a preliminary study of the opinions of radiologists
The large volumes of digital images produced by digital imaging modalities in Radiology have provided the motivation for the development of picture archiving and communication systems (PACS) in an effort to provide an organized mechanism for digital image management. The development of more sophisticated methods of digital image acquisition (Multislice CT and Digital Mammography, for example), as well as the implementation and performance of PACS and Teleradiology systems in a health care environment, have created challenges in the area of image compression with respect to storing and transmitting digital images. Image compression can be reversible (lossless) or irreversible (lossy). While in the former, there is no loss of information, the latter presents concerns since there is a loss of information. This loss of information from diagnostic medical images is of primary concern not only to radiologists, but also to patients and their physicians. In 1997, Goldberg pointed out that "there is growing evidence that lossy compression can be applied without significantly affecting the diagnostic content of images... there is growing consensus in the radiologic community that some forms of lossy compression are acceptable". The purpose of this study was to explore the opinions of expert radiologists, and related professional organizations on the use of irreversible compression in routine practice The opinions of notable radiologists in the US and Canada are varied indicating no consensus of opinion on the use of irreversible compression in primary diagnosis, however, they are generally positive on the notion of the image storage and transmission advantages. Almost all radiologists are concerned with the litigation potential of an incorrect diagnosis based on irreversible compressed images. The survey of several radiology professional and related organizations reveals that no professional practice standards exist for the use of irreversible compression. Currently, the only standard for image compression is stated in the ACR's Technical Standards for Teleradiology and Digital Image Management.
MICE: a mouse imaging collaboration environment
Jacek Szymanski, Chris Flask, David Wilson, et al.
With the ever-increasing complexity of science and engineering, many important research problems are being addressed by collaborative, multidisciplinary teams. We present a web-based collaborative environment for small animal imaging research, called the Mouse Imaging Collaboration Environment (MICE). MICE provides an effective and user-friendly tool for managing and sharing of the terabytes of high-resolution and high-dimension image data generated at small animal imaging core facilities. We describe the design of MICE and our experience in the implementation and deployment of a beta-version baseline-MICE. The baseline-MICE provides an integrated solution from image data acquisition to end-user access and long-term data storage at our UH/Case Small Animal Imaging Resource Center. As image data is acquired from scanners, it is pushed to the MICE server which automatically stores it in a directory structure according to its DICOM metadata. The directory structure reflects imaging modality, principle investigators, animal models, scanning dates and study details. Registered end-users access this imaging data through an authenticated web-interface. Thumbnail images are created by custom scripts running on the MICE server while data down-loading is achieved through standard web-browser ftp. MICE provides a security infrastructure that manages user roles, their access privileges such as read/write, and the right to modify the access privileges. Additional data security measures include a two server paradigm with the Web access server residing outside a network firewall to provide access through the Internet, and the imaging data server - a large RAID storage system supporting flexible backup policies - residing behind the protected firewall with a dedicated link to the Web access server. Direct network link to the RAID storage system outside the firewall other than this dedicated link is not permitted. Establishing the initial image directory structure and letting the project leader manage data access through a web-interface represent Phase I implementation. In Phase II, features for uploading image analysis scripts and results back to the MICE server will be implemented, as well as mechanisms facilitating asynchronous and synchronous discussion, annotation, and analysis. Most of MICE features are being implemented in the Plone5 object-oriented database environment which greatly shortens developmental time and effort by the reuse of a variety of Plone's open-source modules for Content Management Systems.7, 8 The open-source modules are well suited as an implementation basis of MICE and provide data integration as a built-in primitive.
Impact of volumetric ultrasound on PACS
Steven Horii M.D., Alberto Goldszal, Regina Redfern, et al.
The purpose of this study was to determine if the size of ultrasound examinations was increasing over time. The primary reasons for this are believed to be an increased number of images per study, the incorporation of "cine loops", and increased use of color flow Doppler. The result of this study, if it supports the hypothesis that ultrasound study size is increasing, would be directly applicable to planning for future expansion of storage in the Ultrasound PACS. Data were obtained from the ultrasound PACS server for number of studies, number of images, and total stored volume for sampled months (January and July of 2003 - 2006). The investigators believed that these months would provide a reasonable sample of study size as examination types did not vary significantly from month to month (based on Departmental statistics). The Radiology Department's information system (RIS) was used to determine total yearly ultrasound examination volume to determine the trend over time. Because no protected health information (PHI) was to be used in this study, the investigators believed that no IRB approval was necessary. The number of studies done per month was more variable than the investigators had believed. One month in particular (July, 2003) had an anomalously large number of studies. However, despite this, computations of the number of images per study, the total data volume per study, and the average amount of data per image did show an increasing trend as expected. Also, the total volume of data stored showed an increasing trend over the study time period. The investigators' hypothesis that examination size is increasing has been demonstrated to be true for the months sampled. From Departmental data, the investigators know that the most recent ultrasound yearly volume increased approximately ten percent over the previous year, and that trend was also seen for the study period (from 7-10 percent per year increase in volume). With the information that the examination size is also increasing, the Department can make better plans for future expansion of the Ultrasound PACS storage system. Ultrasound examination size is increasing, largely because of the increased use of cine loops. A change to using more of these to replace single static images will further increase examination size.
Poster Session
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Content-based image retrieval in picture archiving and communication system
Yongqiang Tan, Jianguo Zhang, Yanqing Hua, et al.
Traditionally, Picture Archiving and Communication Systems (PACS) use textual-based retrieval, which have their limitations. General-purposed content-based image retrieval (CBIR) systems often do not perform well in medical images and are not integrated with PACS and Radiology Information System (RIS). In this presentation we design a CBIR system that is integrated with PACS and RIS, by using a user-supplied query image to retrieve similar images from PACS and get corresponding reports from RIS. We also employ ACR index for radiological diagnosis to reduce the search space and to provide meaningful results in our CBIR system. We use high resolution CT lung images as the test data. A key image is selected for each series, and after a radiologist delineates the pathology bearing region, local texture features as well as ACR indexes and series UID are stored in a CBIR server. Series UID can be used to retrieve images from PACS and to obtain corresponding reports from RIS. The system is a useful learning tool for radiology education and can provide valuable references for radiologists when a new case comes.
The impact of lossless image compression to radiographs
Thomas M. Lehmann, Jürgen Abel, Claudia Weiss
The increasing number of digital imaging modalities results in data volumes of several Tera Bytes per year that must be transferred and archived in a common-sized hospital. Hence, data compression is an important issue for picture archiving and communication systems (PACS). The effect of lossy image compression is frequently analyzed with respect to images from a certain modality supporting a certain diagnosis. However, novel compression schemes have been developed recently allowing efficient but lossless compression. In this study, we compare the lossless compression schemes embedded in the tagged image file format (TIFF), graphics interchange format (GIF), and Joint Photographic Experts Group (JPEG 2000 II) with the Borrows-Wheeler compression algorithm (BWCA) with respect to image content and origin. Repeated measures ANOVA was based on 1.200 images in total. Statistically significant effects (p < 0,0001) of compression scheme, image content, and image origin were found. Best mean compression factor of 3.5 (2.272 bpp) is obtained applying BTW to secondarily digitized radiographs of the head, while the lowest factor of 1,05 (7.587 bpp) resulted from the TIFF packbits algorithm applied to pelvis images captured digitally. Over all, the BWCA is slightly but significantly more effective than JPEG 2000. Both compression schemes reduce the required bits per pixel (bpp) below 3. Also, secondarily digitized images are more compressible than the directly digital ones. Interestingly, JPEG outperforms BWCA for directly digital images regardless of image content, while BWCA performs better than JPEG on secondarily digitized radiographs. In conclusion, efficient lossless image compression schemes are available for PACS.
Development of a mobile emergency patient information and imaging communication system based on CDMA-1X EVDO
Keon Ho Yang, Haijo Jung, Won-Suk Kang, et al.
The wireless mobile service with a high bit rate using CDMA-1X EVDO is now widely used in Korea. Mobile devices are also increasingly being used as the conventional communication mechanism. We have developed a web-based mobile system that communicates patient information and images, using CDMA-1X EVDO for emergency diagnosis. It is composed of a Mobile web application system using the Microsoft Windows 2003 server and an internet information service. Also, a mobile web PACS used for a database managing patient information and images was developed by using Microsoft access 2003. A wireless mobile emergency patient information and imaging communication system is developed by using Microsoft Visual Studio.NET, and JPEG 2000 ActiveX control for PDA phone was developed by using the Microsoft Embedded Visual C++. Also, the CDMA-1X EVDO is used for connections between mobile web servers and the PDA phone. This system allows fast access to the patient information database, storing both medical images and patient information anytime and anywhere. Especially, images were compressed into a JPEG2000 format and transmitted from a mobile web PACS inside the hospital to the radiologist using a PDA phone located outside the hospital. Also, this system shows radiological images as well as physiological signal data, including blood pressure, vital signs and so on, in the web browser of the PDA phone so radiologists can diagnose more effectively. Also, we acquired good results using an RW-6100 PDA phone used in the university hospital system of the Sinchon Severance Hospital in Korea.
Applying XDS for sharing CDA-based medical records
Joong Il Kim, Bong Mun Jang, Dong Hoon Han, et al.
Many countries have set long-term objectives for establishing an Electronic Healthcare Records system(EHRs). Various IT Strategies note that integration of EHR systems has a high priority. Because the EHR systems are based on different information models and different technology platforms, one of the key integration problems in the realization of the EHRs for the continuity of patient care, is the inability to share patient records between various institutions. Integrating the Healthcare Enterprise (IHE) committee has defined the detailed implementations of existing standards such as DICOM, HL7, in a publicly available document called the IHE technical framework (IHE-TF). Cross-enterprise document sharing (XDS), one of IHE technical frameworks, is describing how to apply the standards into the information systems for the sharing of medical documents among hospitals. This study aims to design Clinical Document Architecture (CDA) schema based on HL7, and to apply implementation strategies of XDS using this CDA schema.
The application of multilayer tree structure in DICOM
In order to enhance the sharing of DICOM, we have proposed to introduce XML into the DICOM Data Dictionary and file system (SPIE2005 5748-57)1, which can extend the readability and the expansibility of DICOM files. In our research, we will improve the data structure of DICOM on the basis of the idea we proposed. We change the one-dimension array into the multilayer tree structure. We also change the original DICOM Dictionary, which consists of numerical code, into the structured Data Dictionary according to the technique of XML. All of the elements are in the special modules. The idea of modulization promotes the searching efficiency and reduces the data redundancy. Data conversion replaces DICOM numerical code with character string tags containing explicit meaning. These information modules are also formed as a multilayer tree structure according to their modules, and they are kept as this structure in storage, transmission and display. After being added and translated, the private data (such as a Diagnostic Report) will be linked directly as a new child-node to the root-node so that the information is available without any special Data Dictionary. In this way, we can extend the capacity of data elements, integrate data from different sources, and enlarge the scope of data sharing in DICOM.
Development of patient collation system by kinetic analysis for chest dynamic radiogram with flat panel detector
In the picture archiving and communication system (PACS) environment, it is important that all images be stored in the correct location. However, if information such as the patient's name or identification number has been entered incorrectly, it is difficult to notice the error. The present study was performed to develop a system of patient collation automatically for dynamic radiogram examination by a kinetic analysis, and to evaluate the performance of the system. Dynamic chest radiographs during respiration were obtained by using a modified flat panel detector system. Our computer algorithm developed in this study was consisted of two main procedures, kinetic map imaging processing, and collation processing. Kinetic map processing is a new algorithm to visualize a movement for dynamic radiography; direction classification of optical flows and intensity-density transformation technique was performed. Collation processing consisted of analysis with an artificial neural network (ANN) and discrimination for Mahalanobis' generalized distance, those procedures were performed to evaluate a similarity of combination for the same person. Finally, we investigated the performance of our system using eight healthy volunteers' radiographs. The performance was shown as a sensitivity and specificity. The sensitivity and specificity for our system were shown 100% and 100%, respectively. This result indicated that our system has excellent performance for recognition of a patient. Our system will be useful in PACS management for dynamic chest radiography.
HIPAA-compliant automatic monitoring system for RIS-integrated PACS operation
As a governmental regulation, Health Insurance Portability and Accountability Act (HIPAA) was issued to protect the privacy of health information that identifies individuals who are living or deceased. HIPAA requires security services supporting implementation features: Access control; Audit controls; Authorization control; Data authentication; and Entity authentication. These controls, which proposed in HIPAA Security Standards, are Audit trails here. Audit trails can be used for surveillance purposes, to detect when interesting events might be happening that warrant further investigation. Or they can be used forensically, after the detection of a security breach, to determine what went wrong and who or what was at fault. In order to provide security control services and to achieve the high and continuous availability, we design the HIPAA-Compliant Automatic Monitoring System for RIS-Integrated PACS operation. The system consists of two parts: monitoring agents running in each PACS component computer and a Monitor Server running in a remote computer. Monitoring agents are deployed on all computer nodes in RIS-Integrated PACS system to collect the Audit trail messages defined by the Supplement 95 of the DICOM standard: Audit Trail Messages. Then the Monitor Server gathers all audit messages and processes them to provide security information in three levels: system resources, PACS/RIS applications, and users/patients data accessing. Now the RIS-Integrated PACS managers can monitor and control the entire RIS-Integrated PACS operation through web service provided by the Monitor Server. This paper presents the design of a HIPAA-compliant automatic monitoring system for RIS-Integrated PACS Operation, and gives the preliminary results performed by this monitoring system on a clinical RIS-integrated PACS.
Interactive radiological education file system integrated with PACS
Myung Jin Shin, Ik Soo Choi
Radiological images, more specifically CT and MRI, are prevailing throughout most clinical practice and being important tools for better understanding of normal and abnormal cross-sectional anatomy. Since PACS has been introduced and implemented in 2000, a lot of radiological images are filed for the medical education. Easy and convenient on-line accessibility of PACS integrated with RIS or HIS makes those medical images more flexible to follow up during daily practice and to be materialized for building educational files. One of the most advantage of this interactive education file system is its versatility simply because of this system is integrated with PACS. We will present our interactive radiological education file system integrated with PACS. The contents of this exhibition will contain; 1) the concept of our education file system, 2) the methods of follow-up cases and building-up files, 3) the diversity of educational materials integrated with PACS, 4) the user interface in reviewing files interactively, 5) future perspectives of interactive radiological education file system in conjunction with a variety of other medical education system or computer aided diagnosis and 6) the design of system architecture.
Sharing medical images: a proposal of a reference image database
Due to increasing number of digital images used in medical diagnosis, the image processing and analysis are becoming essential for many tasks in medicine. One of the obstacles within the field of medical image processing is the lack of reference image datasets freely available for groups and/or individual users, in order to evaluate their new methods and applications. In order to improve this situation, this work presents the development of a framework to make available a free, online, multipurpose and multimodality medical image database for software and algorithm evaluation. The project is implemented as a distributed architecture for medical image database including a publishing workflow, authoring tools, and role-based access control. Our effort aims to offer a testbed and a set of resources including software, links to scientific papers, gold standards, reference and post-processed images, enabling the medical image processing community (scientists, physicians, students and industrials) to be more aware of evaluation issues. The proposed approach has been used as an electronic teaching system in Radiology as well.
Automatic orientation correction for radiographs
In picture archiving and communications systems (PACS), images need to be displayed in standardized ways for radiologists' interpretations. However, for most radiographs acquired by computed radiography (CR), digital radiography (DR), or digitized films, the image orientation is undetermined because of the variation of examination conditions and patient situations. To address this problem, an automatic orientation correction method is presented. It first detects the most indicative region for orientation in a radiograph, and then extracts a set of low-level visual features sensitive to rotation from the region. Based on these features, a trained classifier based on a support vector machine is employed to recognize the correct orientation of the radiograph and reorient it to a desired position. A large-scale experiment has been conducted on more than 12,000 radiographs covering a large variety of body parts and projections to validate the method. The overall performance is quite promising, with the success rate of orientation correction reaching 95.2%.
Implementation of a fault-tolerant PACS over a grid architecture
The goal of this paper is to describe the experience of the Heart Institute (InCor) on the implementation of a fault-tolerant Picture Archiving and Communication System (PACS) over a data grid architecture. The system is centered on a DICOM image server with a distributed storage and failover capability. The proposed data grid architecture is deployed over a gigabit Ethernet network which integrates the two main public Hospitals in Sao Paulo and one University Hospital in Rio de Janeiro, both in Brazil. Distributed data storage in the three sites is managed by the Storage Resource Broker (SRB) developed at the University of California at San Diego. The architecture of the implemented PACS image server can be divided into two major functional modules: a) DICOM protocol handler; b) Distributed storage of image data. Fault-tolerance is achieved by injecting redundancy into the modules, which are provided with failover capability. The DICOM protocol handler comprises a series of server processes hosted by different machines and a load-balancer node which distributes the computational load among the servers. The load balancer is provided with a backup node which is triggered in case of failure, thus assuring the continuous operation of the system. Distributed storage of image data is implemented as a thin software layer over the SRB. Image data are replicated at the three sites, so the PACS server is able to retrieve image data even when only a single site is available. A prototype of the DICOM image server has been deployed in this environment and is currently under evaluation.
Integration of LDSE and LTVS logs with HIPAA compliant auditing system (HCAS)
Zheng Zhou, Brent J. Liu, H. K. Huang, et al.
The deadline of HIPAA (Health Insurance Portability and Accountability Act) Security Rules has passed on February 2005; therefore being HIPAA compliant becomes extremely critical to healthcare providers. HIPAA mandates healthcare providers to protect the privacy and integrity of the health data and have the ability to demonstrate examples of mechanisms that can be used to accomplish this task. It is also required that a healthcare institution must be able to provide audit trails on image data access on demand for a specific patient. For these reasons, we have developed a HIPAA compliant auditing system (HCAS) for image data security in a PACS by auditing every image data access. The HCAS was presented in 2005 SPIE. This year, two new components, LDSE (Lossless Digital Signature Embedding) and LTVS (Patient Location Tracking and Verification System) logs, have been added to the HCAS. The LDSE can assure medical image integrity in a PACS, while the LTVS can provide access control for a PACS by creating a security zone in the clinical environment. By integrating the LDSE and LTVS logs with the HCAS, the privacy and integrity of image data can be audited as well. Thus, a PACS with the HCAS installed can become HIPAA compliant in image data privacy and integrity, access control, and audit control.
Rib shape recognition in lung x-ray images for intelligent assistance
The purpose of this research is to develop a method for recognizing shapes of ribs in chest x-rays, which can be utilized as intelligent assistance to diagnosis to decrease false positives (FPs) due to ribs in chest CAD and automatically generate a schema in report. Shapes of ribs are manually extracted from several CR images to create a rib shape model using PDM, in which shapes of anterior/posterior ribs are represented as sets of coordinates and an arbitrary shape of a rib is expressed only with principle components that have a high contribution ratio to shape variation. Shapes of ribs in a chest X-ray image are identified as follows: (a) Identify the lung field. (b) Find an allowable range of weights of principle components in the shape model within which the model aligns to an edge of the lung field (a). (c) Create several shape model images by applying different weights of principle components. (d) Apply a six-direction Gabor filter to the X-ray image and each one of the shape model images to create an image containing only rib elements. (e) From images created in (d), search for a shape model image that shows the highest correlation coefficient with the X-ray image.We applied the rib shape model to 100 test images while changing weights of principle components. We were able to identify positions of ribs and anatomical rib numbers with an average margin of error being no more than two fifths of a rib and a half of a rib in case of anterior ribs.