Bone age assessment is a procedure performed in pediatric patients to quickly evaluate parameters of maturation and growth from a left hand and wrist radiograph. Pietka and Cao have developed a Computer-aided diagnosis (CAD) method of bone age assessment based on a digital hand atlas. The aim of this paper is to extend their work by automatically select the best representative image from a group of normal children based on specific bony features that reflect skeletal maturity. The group can be of any ethnic origin and gender from one year to 18 year old in the digital atlas. This best representative image is defined as the "average" image of the group that can be augmented to Piekta and Cao's method to facilitate in the bone age assessment process.
Proc. SPIE. 5371, Medical Imaging 2004: PACS and Imaging Informatics
KEYWORDS: Image encryption, Surgery, Medical imaging, Digital imaging, Image transmission, Data communications, Information security, Computer security, Network security, Picture Archiving and Communication System
Medical image security in a PACS environment has become a pressing issue as communications of images increasingly extends over open networks, and hospitals are currently hard-pushed by Health Insurance Portability and Accountability Act (HIPAA) to be HIPPA complaint for ensuring health data security. Other security-related guidelines and technical standards continue bringing to the public attention in healthcare. However, there is not an infrastructure or systematic method to implement and deploy these standards in a PACS. In this paper, we first review DICOM Part15 standard for secure communications of medical images and the HIPAA impacts on PACS security, as well as our previous works on image security. Then we outline a security infrastructure in a HIPAA mandated PACS environment using a dedicated PACS image security server. The server manages its own database of all image security information. It acts as an image Authority for checking and certificating the image origin and integrity upon request by a user, as a secure DICOM gateway to the outside connections and meanwhile also as a PACS operation monitor for HIPAA supporting information.
Proc. SPIE. 5371, Medical Imaging 2004: PACS and Imaging Informatics
KEYWORDS: Computer aided diagnosis and therapy, Databases, Image processing, Radiography, Bone, Medical imaging, Digital imaging, Radiology, Standards development, Picture Archiving and Communication System
Bone age assessment is a procedure frequently performed in pediatric patients to evaluate their growth disorder. A commonly used method is by atlas matching with a small reference set of Greulich-Pyle atlas that was developed in 1950s based on middle class white populations. The old Greulich-Pyle atlas is not fully applicable for today’s children especially regarding the standard development in other racial groups. We have collected over 1000 hand and wrist images for normal boys and girls of Caucasian, African, Hispanic and Asian descents from newborn to 18 years of age. In this paper we present an atlasing method that will automatically select the reference images from the normal collection database to form a digital atlas. Compared with the book-based Greulich-Pyle atlas, the digital atlas is easy to access and can always be replenished with new images reflecting more accurately the current population and skeletal development.
As PACS and related imaging technologies become more common in the healthcare setting, better methods are needed for training radiologists, allied healthcare and IT providers to understand and use them effectively. We presented a PACS Simulator in 2002 and a RIS integrated PACS Simulator in 2003. In this presentation we integrate a web-based image distribution and display system with the Simulator to complete the simulation of clinical PACS workflow. The Simulator consists of RIS Simulator, modality Simulator, DICOM gateway, PACS controller, clinical viewing workstations, PACS monitor system and a web server. The addition web server distributes images to browser-based display clients for display and manipulation using web technology. Using this Simulator, trainees can: (1) Observe RIS/PACS operation with web image distribution, component by component, (2) Trace image data flow through each component, (3) Query, retrieve and review images at web display clients, (4) Induce failure in a component to observe its impact on the entire RIS/PACS operation. The Simulator has been developed as a stand-alone tool for trainees to understand RIS/PACS concept and appreciate RIS/PACS workflow with hands-on experience. The Simulator has been applied in many training classes, and the addition of web server will significantly improve its training value.
We have developed and evaluated a novel image-matching method for medical images. This method allows the radiologist to search through - in a matter of seconds - large medical databases containing thousands of patients. To illustrate the usefulness of this method in a clinical setting, we have employed this method as a diagnostic support tool for pediatric brain diseases. To this aim, we have assembled a database containing Magnetic Resonance (MR) brain images of 2500 patients between ages 0 and 18 with known brain lesions. As the images are added to the database, they are registered to a global coordinate system. In addition, regions of interests (ROI) are labeled, and sophisticated image processing techniques are used to extract image parameters from the ROIs and from the entire MR image. To perform a clinically realistic search through this database, we have established a training testbed at Childrens Hospital Los Angeles for acquiring MR images from our PACS server of patients with unknown lesions. We have matched these images with the images in the pediatric brain MR database containing known lesions using our image-matching method. An expert pediatric neuroradiologist evaluated the search results. We found that in most cases, our image-matching method is able to retrieve images with relevant diagnostic content, making it highly attractive as a diagnostic support tool.
Proc. SPIE. 5033, Medical Imaging 2003: PACS and Integrated Medical Information Systems: Design and Evaluation
KEYWORDS: Image encryption, Digital image processing, Image segmentation, Medical imaging, Digital imaging, Image transmission, Computer security, Device simulation, Network security, Picture Archiving and Communication System
Health data security, characterized in terms of data privacy, authenticity, and integrity, is a vital issue when digital images and other patient information are transmitted through public networks in telehealth applications such as teleradiology. Mandates for ensuring health data security have been extensively discussed (for example The Health Insurance Portability and Accountability Act, HIPAA) and health informatics guidelines (such as the DICOM standard) are beginning to focus on issues of data continue to be published by organizing bodies in healthcare; however, there has not been a systematic method developed to ensure data security in medical imaging Because data privacy and authenticity are often managed primarily with firewall and password protection, we have focused our research and development on data integrity. We have developed a systematic method of ensuring medical image data integrity across public networks using the concept of the digital envelope. When a medical image is generated regardless of the modality, three processes are performed: the image signature is obtained, the DICOM image header is encrypted, and a digital envelope is formed by combining the signature and the encrypted header. The envelope is encrypted and embedded in the original image. This assures the security of both the image and the patient ID. The embedded image is encrypted again and transmitted across the network. The reverse process is performed at the receiving site. The result is two digital signatures, one from the original image before transmission, and second from the image after transmission. If the signatures are identical, there has been no alteration of the image. This paper concentrates in the method and evaluation of the digital image envelope.
Last year we presented a Fault-Tolerant Backup Archive using an Application Service Provider (ASP) model for disaster recovery. The purpose of this paper is to update and provide clinical experiences related towards implementing the ASP model archive solution for short-term backup of clinical PACS image data as well as possible applications other than disaster recovery. The ASP backup archive provides instantaneous, automatic backup of acquired PACS image data and instantaneous recovery of stored PACS image data all at a low operational cost and with little human intervention. This solution can be used for a variety of scheduled and unscheduled downtimes that occur on the main PACS archive. A backup archive server with hierarchical storage was implemented offsite from the main PACS archive location. Clinical data from a hospital PACS is sent to this ASP storage server in parallel to the exams being archived in the main server. Initially, connectivity between the main archive and the ASP storage server is established via a T-1 connection. In the future, other more cost-effective means of connectivity will be researched such as the Internet 2. We have integrated the ASP model backup archive with a clinical PACS at Saint John's Health Center and has been operational for over 6 months. Pitfalls encountered during integration with a live clinical PACS and the impact to clinical workflow will be discussed. In addition, estimations of the cost of establishing such a solution as well as the cost charged to the users will be included. Clinical downtime scenarios, such as a scheduled mandatory downtime and an unscheduled downtime due to a disaster event to the main archive, were simulated and the PACS exams were sent successfully from the offsite ASP storage server back to the hospital PACS in less than 1 day. The ASP backup archive was able to recover PACS image data for comparison studies with no complex operational procedures. Furthermore, no image data loss was encountered during the recovery. During any clinical downtime scenario, the ASP backup archive server can repopulate a clinical PACS quickly with the majority of studies available for comparison during the interim until the main PACS archive is fully recovered.
Proc. SPIE. 5033, Medical Imaging 2003: PACS and Integrated Medical Information Systems: Design and Evaluation
KEYWORDS: Image fusion, Computer aided diagnosis and therapy, Databases, Image segmentation, Radiography, Feature extraction, Bone, Digital imaging, Computer aided design, Picture Archiving and Communication System
Bone age assessment is a procedure frequently performed in pediatric patients to evaluate their growth disorder. A commonly used method is atlas matching by a visual comparison of a hand radiograph with a small reference set of old Greulich-Pyle atlas. We have developed a new digital hand atlas with a large set of clinically normal hand images of diverse ethnic groups. In this paper, we will present our system design and implementation of the digital atlas database to support the computer-aided atlas matching for bone age assessment. The system consists of a hand atlas image database, a computer-aided diagnostic (CAD) software module for image processing and atlas matching, and a Web user interface. Users can use a Web browser to push DICOM images, directly or indirectly from PACS, to the CAD server for a bone age assessment. Quantitative features on the examined image, which reflect the skeletal maturity, are then extracted and compared with patterns from the atlas image database to assess the bone age. The digital atlas method built on a large image database and current Internet technology provides an alternative to supplement or replace the traditional one for a quantitative, accurate and cost-effective assessment of bone age.
Many educational courses have been designed for training radiologists and allied healthcare providers to operate PACS workstations. There are yet tools available for educational training of PACS concepts and workflow analysis. We have designed and implemented a RIS/PACS Simulator for this purpose. The RIS/PACS Simulator consists of six key components simulating a typical clinical RIS/PACS: RIS simulator, acquisition modality Simulator (AMS), DICOM gateway, PACS controller (UNIX-based), clinical viewing workstation, and network infrastructure with a 100mbits/sec Ethernet switch connecting to all these components. A generic RIS and a generic DICOM compliant PACS software package are used to simulate normal clinical data flow. Using this simulator, trainees can:
1. Observe clinical RIS/PACS operation, component by component
2. Trace image flow through each component
3. Identify PACS data flow bottle neck
4. Induce failure in a component to observe its impact on the PACS workflow and operation
RIS/PACS simulator is a valuable tool for participants to gain knowledge of the complexity of RIS/PACS data flow with hands-on experience. As a stand-alone system, it also becomes a good test bed for evaluation of medical imaging applications without interrupting clinical workflow.
Tele-imaging consultation requires high performance network, which can be fulfilled by Internet2 technology. International partnership allows institutions around the world to join Internet2 outside of North America. Once this partnership has been formed, there are three major issues of connectivity: commercial issue, cost of international link and performance issue. Those issues are worthy to be considered before establishing the International Internet2 connection. Since the international link involves the collaborative efforts from vendors, there exists infrastructure looping inside US, which degrade the performance and raise the cost.
Image workflow in today's Picture Archiving and Communication Systems (PACS) is controlled from fixed Display Workstations (DW) using proprietary control interfaces. A remote access to the Hospital Information System (HIS) and Radiology Information System (RIS) for urgent patient information retrieval does not exist or gradually become available. The lack for remote access and workflow control for HIS and RIS is especially true when it comes to medical images of a PACS on Department or Hospital level. As images become more complex and data sizes expand rapidly with new image techniques like functional MRI, Mammography or routine spiral CT to name a few, the access and manageability becomes an important issue. Long image downloads or incomplete work lists cannot be tolerated in a busy health care environment. In addition, the domain of the PACS is no longer limited to the imaging department and PACS is also being used in the ER and emergency care units. Thus a prompt and secure access and manageability not only by the radiologist, but also from the physician becomes crucial to optimally utilize the PACS in the health care enterprise of the new millennium. The purpose of this paper is to introduce a concept and its implementation of a remote access and workflow control of the PACS combining wireless, Internet and Internet2 technologies. A wireless device, the Personal Digital Assistant (PDA), is used to communicate to a PACS web server that acts as a gateway controlling the commands for which the user has access to the PACS server. The commands implemented for this test-bed are query/retrieve of the patient list and study list including modality, examination, series and image selection and pushing any list items to a selected DW on the PACS network.
Failure of PACS archive server would cripple the entire PACS operation. Last year we demonstrated that it was possible to design a fault-tolerant (FT) server with 99.999% uptime. The FT design was based on a triple modular redundancy with a simple majority vote to automatically detect and mask a faulty module. The purpose of this presentation is to report on its continuous developments in integrating with external mass storage devices, and applying as an Application Service Provider (ASP) back-up archive server. ASP back-up archive is to provide instantaneous automatic backup of PACS image data and instantaneous recovery of PACS image data in the event of disaster. FT server is used as an off-site backup-archive PACS server from the main PACS archive locations. Clinical data from a hospital PACS is sent to the FT server in parallel to the exams being archived in the main server. A disaster scenario is simulated and the PACS data is sent from the offsite FT server back to the hospital PACS. The reliability, functionality and performance of the FT server and external mass storage devices are evaluated during the simulation.
Tele-medical imaging applications require low cost, and high-speed backbone wide area networks (WAN) to carry large amount of imaging data for rapid turn around interpretation. Current low cost commercially WAN is too slow for medical imaging applications, while high speed WAN is too costly. The next generation Internet (NGI) or Internet2 is federal initiatives for the integration of higher speed backbone communication networks (up to 2.4 Gbits/sec) as a means to replace the current inadequate Internet for many applications including medical imaging. This paper describes our preliminary experience of connecting to Internet2 for teleradiology application. A case study is given for the NGI WAN connection between Childrens Hospital Los Angeles and National Library of Medicine. NGI WAN performance for different image modalities, measured in throughput rate and application response time, were obtained and then compared to the T1 WAN connection between Childrens Hospital Los Angeles and Saint John's Health Center Santa Monica.
Failure of a PACS archive server could cripple an entire PACS operation. Last year we demonstrated that it was possible to design a fault-tolerant (FT) server with 99.999% uptime. The FT design was based on a triple modular redundancy with a simple majority vote to automatically detect and mask a faulty module. The purpose of this presentation is to report on its continuous developments in integrating with external mass storage devices, and to delineate laboratory failover experiments. An FT PACS Simulator with generic PACS software has been used in the experiment. To simulate a PACS clinical operation, image examinations are transmitted continuously from the modality simulator to the DICOM gateway and then to the FT PACS server and workstations. The hardware failures in network, FT server module, disk, RAID, and DLT are manually induced to observe the failover recovery of the FT PACS to resume its normal data flow. We then test and evaluate the FT PACS server in its reliability, functionality, and performance.
Proc. SPIE. 4685, Medical Imaging 2002: PACS and Integrated Medical Information Systems: Design and Evaluation
KEYWORDS: Data modeling, Data storage, Networks, Image restoration, Data acquisition, Data archive systems, Information technology, Data backup, Data storage servers, Picture Archiving and Communication System
A single point of failure in PACS during a disaster scenario is the main archive storage and server. When a major disaster occurs, it is possible to lose an entire hospital's PACS data. Few current PACS archives feature disaster recovery, but the design is limited at best. These drawbacks include the frequency with which the back-up is physically removed to an offsite facility, the operational costs associated to maintain the back-up, the ease-of-use to perform the backup consistently and efficiently, and the ease-of-use to perform the PACS image data recovery. This paper describes a novel approach towards a fault-tolerant solution for disaster recovery of short-term PACS image data using an Application Service Provider model for service. The ASP back-up archive provides instantaneous, automatic backup of acquired PACS image data and instantaneous recovery of stored PACS image data all at a low operational cost. A back-up archive server and RAID storage device is implemented offsite from the main PACS archive location. In the example of this particular hospital, it was determined that at least 2 months worth of PACS image exams were needed for back-up. Clinical data from a hospital PACS is sent to this ASP storage server in parallel to the exams being archived in the main server. A disaster scenario was simulated and the PACS exams were sent from the offsite ASP storage server back to the hospital PACS. Initially, connectivity between the main archive and the ASP storage server is established via a T-1 connection. In the future, other more cost-effective means of connectivity will be researched such as the Internet 2. A disaster scenario was initiated and the disaster recovery process using the ASP back-up archive server was success in repopulating the clinical PACS within a short period of time. The ASP back-up archive was able to recover two months of PACS image data for comparison studies with no complex operational procedures. Furthermore, no image data loss was encountered during the recovery.
A dedicated small animal x-ray computed tomography system, named MicroCT, has been developed to mutagenize small animals such as mice for anatomical phenotypes in vivo. However, its output volumes are very large, and it is a tough job to transfer, archive and mange them in order. We designed a DICOM standard conformance image acquisition gateway (IAG) to interface the MicroCT system with PACS. The IAG consists of 4 major modules. First module detects the output of MicroCT in shared disk, and offers a GUI for user to modify or add information relative to imaging. Second module is DICOM encoding process, which creates DICOM objects, fills the DICOM header structure with information both from log files and manual settings, and converts raw image data to DICOM format. Third module is for local image management, which consists of an image database and a management tool. The last module is a communication process working as DICOM Storage SCU (Service Class User) to send encoded DICOM images to remote PACS computers or DICOM conformance viewers for display or image management. Using the developed acquisition gateway can integrate MicroCT imaging system into a PACS infrastructure, and enable potential users to obtain benefits from matured PACS technologies.
The Hong Kong Polytechnic University has a Radiography Division under the Development of Optometry and Radiography. The Division trains both diagnostic and therapeutic radiographers with 60 students/year and offers a B.Sc. degree. In addition the Division together with the University Health Service operates a radiography clinic with radiology consultation from radiologists from other hospitals and clinics. This paper describers the implementation of a PACS in the Division for radiography training, and for clinical service.
Proc. SPIE. 3980, Medical Imaging 2000: PACS Design and Evaluation: Engineering and Clinical Issues
KEYWORDS: Image encryption, Digital imaging, Mammography, Medical imaging applications, Computer security, Digital mammography, Asynchronous transfer mode, Network security, Picture Archiving and Communication System, Breast imaging
Tele-medical imaging applications require low cost, and high- speed backbone wide area networks (WAN) to carry large amount of imaging data for rapid turn around interpretation. Current low cost commercially available WAN is too slow for medical imaging applications, while high speed WAN is too costly. Internet2 or Next Generation Internet (NGI) emerges as a good candidate for tele-medical imaging applications because of its high speed and low cost. This paper describes the beginning of a three-year project on exploring the possibility of using NGI for medical imaging applications. Connectivity of a private ATM to the Internet2 is first discussed, followed by methods of preserving data integrity in the public networks. Two medical imaging applications in telemammography and interactive teaching of breast imaging are presented. A preliminary plan on methods of evaluating the performance of the NGI is followed.
Proc. SPIE. 3976, Medical Imaging 2000: Image Display and Visualization
KEYWORDS: Human-machine interfaces, Computer aided diagnosis and therapy, Databases, Image processing, Computing systems, Bone, Medical imaging, Digital imaging, Computer aided design, Picture Archiving and Communication System
A frequently used assessment method of skeletal age is atlas matching by a radiological examination of a hand image against a small set of Greulich-Pyle patterns of normal standards. The method however can lead to significant deviation in age assessment, due to a variety of observers with different levels of training. The Greulich-Pyle atlas based on middle upper class white populations in the 1950s, is also not fully applicable for children of today, especially regarding the standard development in other racial groups. In this paper, we present our system design and initial implementation of a digital hand atlas and computer-aided diagnostic (CAD) system for Web-based bone age assessment. The digital atlas will remove the disadvantages of the currently out-of-date one and allow the bone age assessment to be computerized and done conveniently via Web. The system consists of a hand atlas database, a CAD module and a Java-based Web user interface. The atlas database is based on a large set of clinically normal hand images of diverse ethnic groups. The Java-based Web user interface allows users to interact with the hand image database form browsers. Users can use a Web browser to push a clinical hand image to the CAD server for a bone age assessment. Quantitative features on the examined image, which reflect the skeletal maturity, is then extracted and compared with patterns from the atlas database to assess the bone age.
Bone age assessment of children using a hand x-ray image is traditionally performed by comparing it with an atlas of a limited number of images. This method is not accurate due to the small homogeneous sample of images in the atlas, and the comparison is done qualitatively. A digital hand atlas, on the other hand, can circumvent these disadvantages by collecting a large sample size, identifying the ethnic origins, and using quantitative parameters relevant to bone age for comparison. This paper describes a general framework of the digital hand atlas and how it can be used to assess the skeletal growth of children.
A frequently used assessment method of bone age is atlas matching by a radiological examination of a hand image against a reference set of atlas patterns of normal standards. We are in a process of developing a digital hand atlas with a large standard set of normal hand and wrist images that reflect the skeletal maturity, race and sex difference, and current child development. The digital hand atlas will be used for a computer-aided bone age assessment via Web. We have designed and partially implemented a computer-aided diagnostic (CAD) system for Web-based bone age assessment. The system consists of a digital hand atlas, a relational image database and a Web-based user interface. The digital atlas is based on a large standard set of normal hand an wrist images with extracted bone objects and quantitative features. The image database uses a content- based indexing to organize the hand images and their attributes and present to users in a structured way. The Web-based user interface allows users to interact with the hand image database from browsers. Users can use a Web browser to push a clinical hand image to the CAD server for a bone age assessment. Quantitative features on the examined image, which reflect the skeletal maturity, will be extracted and compared with patterns from the atlas database to assess the bone age. The relevant reference imags and the final assessment report will be sent back to the user's browser via Web. The digital atlas will remove the disadvantages of the currently out-of-date one and allow the bone age assessment to be computerized and done conveniently via Web. In this paper, we present the system design and Web-based client-server model for computer-assisted bone age assessment and our initial implementation of the digital atlas database.
We are in the process of conducting a research of full-field direct digital telemammography using three protocols: telediagnosis, teleconsultation, and telemanagement. To conduct this research project, an asynchronous transfer mode network based telemammography system was developed across two remote campuses in our facility. The hardware and software components of this system are detailed. The system was embedded in a clinical environment for a four-month test. Some preliminary study results from the current phase of this study are reported.
The digital breast imaging teaching file developed during the last two years in our laboratory has been used successfully at UCSF (University of California, San Francisco) as a routine teaching tool for training radiology residents and fellows in mammography. Building on this success, we have ported the teaching file from an old Pixar imaging/Sun SPARC 470 display system to our newly designed telemammography display workstation (Ultra SPARC 2 platform with two DOME Md5/SBX display boards). The old Pixar/Sun 470 system, although adequate for fast and high-resolution image display, is 4- year-old technology, expensive to maintain and difficult to upgrade. The new display workstation is more cost-effective and is also compatible with the digital image format from a full-field direct digital mammography system. The digital teaching file is built on a sophisticated computer-aided instruction (CAI) model, which simulates the management sequences used in imaging interpretation and work-up. Each user can be prompted to respond by making his/her own observations, assessments, and work-up decisions as well as the marking of image abnormalities. This effectively replaces the traditional 'show-and-tell' teaching file experience with an interactive, response-driven type of instruction.
Bone age assessment by a radiological examination of a hand and wrist image is a procedure frequently performed in pediatric patients to evaluate growth disorders, determine growth potential in children and monitor therapy effects. The assessment method currently used in radiological diagnosis is based on atlas matching of the diagnosed hand image with the reference set of atlas patterns, which was developed in 1950s and is not fully applicable for children of today. We intent to implement a diagnostic workstation for creating a new reference set of clinically normal images which will serve as a digital atlas and can be used for a computer-assisted bone age assessment. In this paper, we present the initial data- collection and system setup phase of this five-year research program. We describe the system design, user interface implementation and software tool development for collection, visualization, management and processing of clinically normal hand and wrist images.
Full-field direct digital mammography has many advantages over the conventional film/screen imaging detector. Among these are larger dynamic range, lower scattering noise, and the possibility of using it for telemammography applications to alleviate the shortage of expert mammographers. We are in the process of developing a full-field direct digital telemammography imaging chain to investigate its usefulness for telediagnosis, teleconsultation, and telemanagement. This paper describes the first phase of a three-year research program to set up a full-field direct digital mammography (FFDDM) imaging chain at the Breast Imaging Section connecting the University of California, San Francisco Medical Center and the Mt. Zion Hospital in the San Francisco Bay area. The chain consists of two FFDDM system, and two 2,500 line two-monitor workstations. An OC-3 155 Mbits/sec asynchronous transfer mode (ATM) communication network is used to connect the FFDDM and the two workstations. The FFDDM is based on a slot scan CCD detector which can image a full breast with 3,100 X 3,870 pixels, and produce a direct digital image with 50 micron pixel size. Preliminary results of the FFDDM demonstrate that it has a greater dynamic range and lower detector noise than that of a film-screen detector, and that the scattered radiation is reduced without using a grid. However, the spatial resolution is less than that of the conventional screen/film system. The 2K workstation can display simultaneously any two or four full-view mammographic images by either scrolling or subsampling on the two monitors. Display of an image takes about 1.5 seconds from the RAID disks. The ATM can transmit a 32 Mbyte digital mammogram from the FFDDM to the workstation in 3-4 seconds.
We implemented a high resolution display system for viewing digitized mammograms at real-time speeds. This display system has been utilized at the UCSF to develop a digital breast imaging teaching file. The mammography display station is built on a Sun workstation and Pixar processing hardware. It is capable of real-time 2K image display and manipulation, and serves as a basic platform for our digital mammographic teaching file. The teaching file is designed on a sophisticated computer-aided instruction (CAI) model, which simulates the work-up sequences used in imaging interpretation. Our CAI model not only provides answers to questions, but also allows user's detection of imaging abnormalities by pointing at the image. We also developed a software tool with an easy-to-use interface to manage patient images and related information, and manipulate the large quantity of digital mammograms. The display station is found to be adequate for fast display of high resolution digital mammograms. Our sophisticated CAI model integrates the vast image and textual data with visualization software into an interactive mammographic teaching file. This teaching file can be used as a real teaching tool for training radiology residents in mammography.