The system allows the experts of a medical centre to recover and manage information. ⢠Our solution also makes it .... for data storage as well as data recovery.
Development of a System for Access to and Exploitation of Medical Images Pereira, J.; Castro, A.; Ronda, D.; Arcay, B.; Pazos, A.; Computer-Based Medical Systems, 2002. (CBMS 2002). Proceedings of the 15th IEEE Symposium on , 4-7 June 2002 Page(s): 309 -314
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Abstract 1. Introduction 2. System architecture 3. Acquisition 4. Information storage 5. Support tools for the clinical decision-making 6. Web interface 7. Security 8. Results and conclusions
Abstract • This article describes a system for the acquisition, storage and secure remote access to information generated by a hospital’s devices for image diagnosis. • The system allows the experts of a medical centre to recover and manage information. • Our solution also makes it possible to obtain more elaborate results, thanks to the implemented functionalities of image analysis (edge detectors, clustering algorithms, etc.) and the storage of historical diagnosis results that give a certain experience to the application.
Abstract • acquisition, storage and secure • manage information • experience to the application
1. Introduction • They facilitate the access to and the visualization of the digital medical image • PACS [1] (Picture Archiving and Communication Systems). • Computerized Tomography (CT), • Nuclear Magnetic Resonance (NMR), • Positron Emission Tomography (PET),...
• The first generation each manufacturer disposed of his own proprietary format that was usually closed and not easily accessible for other systems, such as the ones derived from the use of a different syntaxis (little endian versus big endian). This provoked situations in which one hospital would have several devices that were incompatible because they could not exchange their information.
• The first generation each manufacturer disposed of his own proprietary format that was usually closed and not easily accessible for other systems • This provoked situations in which one hospital would have several devices that were incompatible because they could not exchange their information.
• In 1982, the ACR (American College of Radiology) and the NEMA (National Electrical Manufacturers Association) decided to work together at a standard that would eliminate these incompatibility problems. After several revisions, they published the DICOM 3 standard in 1988 [2].
• In the nineties, the most important companies of this sector (AGFA, SIEMENS, etc.) • inconsistent interfaces that provoke rejection among the users, difficulties in the follow up of the patient’s clinical history; scarce statistical tools, and nonexistent development modules (API) for the integration of new tools that improve the information obtained from the images.
• In the nineties, the most important companies of this sector (AGFA, SIEMENS, etc.) • difficulties in the follow up of the patient’s clinical history ，scarce statistical tools, • Applicaiton Programming Interfaces , API）
• Moreover, these information systems must also dispose of all the necessary security mechanisms that guarantee the integrity as well as the condifentiality of the medical data they store and transmit
• thus allows the practices of telemedicine, teleformation, telediagnosis and teleconsulting; • it also provides hospitals with a direct access, for instance from an emergency service, where a patients X rays could be consulted instantly. • RIS (Radiology Information System) as well as the HIS (Hospital Information System) [6].
• The graphical user interface (GUI) had to be a user friendly and recognizable environment that integrated all the tools the user disposes of. • We chose to develop a web based interface, because it offers all the advantages of network development: the user can access his system locally or from a remote site. During the construction of our system, we tried to achieve the following objects: scalability, simultaneous and remote access, interaction between heterogeneous systems, possibility to develop new functions, standardized information, fit in the existing structures, secure, use of open standards and user friendly interface and support to the expert’s decisionmaking.
• The graphical user interface (GUI) had to be a user friendly and recognizable environment • We chose to develop a web based interface, because it offers all the advantages of network development
2. System architecture • For the communication between the layers and with other systems inside and outside the hospitals, we defined functional modules that communicate through services. • we propose an architecture that consists of four layers: • the network and acquisition layer, • the storage or database layer, • the analysis and minning layer and • lastly the decision-making support layer.
Figure 1. Functional modules of the system.
3. Acquisition • Image generation equipments can be classified according to the image technology that they generate both in analogue and digital applications.
• If the equipment supports DICOM, image acquisition takes place directly as shown in figure 2. We developed an application that implements the Query/Retrieve and Storage services as defined in part 3 of the DICOM standard. Acting as a SCU (Service Class User), it can be connected to DICOM equipments and acquire the data so as to integrate them in the information system. Equipments that are not DICOM use a kind of bridge for the conversion of images to the DICOM format.
• In order to acquire images from equipments other than DICOM, we have to develop bridges that convert the images with proprietary formats to the DICOM standard. • These black boxes also dispose of the Query/Retrieve and Storage services, but in this case they act as SCPs (Service Class Providers). The connection between the no-DICOM equipments and the standardisation bridge takes place through a periodically programmed FTP (File Transfer Protocol).
Figure 2. Image acquisition mechanisms
4. Information storage • DICOM messages (bitmap+basic identification information) • demographic data (from the HIS) • clinical information (issued by the specialists) and information that is generated by the system itself (result or consequence of the statistical analysis, processing and studies)
• In that respect, the exploitation is oriented towards the level of data that we wish to recover: the recovery of the information is linked to the functionality of the system. This characteristic determines the set of SQL querys that are defined in the system: the information that corresponds to the SQL level is recovered and becomes the basic level to which then information is added in each of the different stages.
• The design of the database is based on the Entity-Relationship model and the implementation is using a relational database management system (RDBMS). From the point of view of the information, the database is the nucleus of the system and is being used by the other components for data storage as well as data recovery.
• The DICOM files consist of the studies that were performed and of the personal and demographic data of the patient, and are stored as BLOB data (Binary Large Object). Thedemographic data however (number of clinical history, name and gender of the patient, etc.) are also stored in a number of tables.
• Even though this means that the information is being replicated, it assures an efficient access to the data, allows us to have a DICOM study as a whole without modifications (maintenance of the standard) and guarantees more data integrity (normalization).
• We optimized the access to the database by creating for each of the images it contains a fast visualization icon (about 50 Kb) linked to the real image. This “preview” is also used to select the study that the expert wishes to recover.
5. Support tools for the clinical decision-making • Our main objectives in this development were the following: • automatic segmentation of medical images, angle measurement • and • visual improvement of the image.
• we had to divide this layer in three perfectly differentiated modules: • tools for measurement, • tools for processing and • analysis and tools for advanced visualization of the images.
• The techniques that are currently being implemented in the system can be divided into two groups: analysis by regions (FCM [7], FKNN [8] and AFCM [9]) and analysis by detection of discontinuities (Canny [10], Heitger [11] and Bezdek’s fuzzy detector [12]).
• We have also included several classic algorithms for digital image processing, which can be of use to the specialist: equalization of the histogram, homomorphic filters, etc.
• The module of advanced visualization is still being tested, but we have already been able to ascertain that for certain pathologies (tumor diagnosis, dental analysis, etc.)
• it is of great importance to have various perspectives of the image, and in particular the third dimension. If the image technique allows it, researchers use 3D reconstructions of the anatomic structure (CT, NMR, etc.) as in figure 3.
6. Web interface • user-friendly • We implemented the interface according to the W3C norms for the construction of HTML pages • The public zone proposes an “image gallery”
• Access to this gallery is determined by three criteria: • modalities, • pathologies • anatomic zones.
Figure 3. Interface of the advanced visualization of medical images.
7. Security • we followed the ISO 7498-2 safety norm, • Spain’s Organic Law 15/99 for the Protection of PersonalData (December 13th) • We selected the SSL protocol because it is standardized and provides the highest security level.
8. Results and conclusions • We tested the way the system functions at the Hospital Modelo (HM) and the Instituto Medico Quirurgico San Rafael (IMQSR), and at the Hospital Fundacion Publica Virxe da Xunqueira (HFPVX).
• 5 km from the HM and the IMQSR • 100 km from the HFPVX • The communication infrastructure consists of Ethernet and Fast Ethernet networks • the IMQSR uses a dedicated ISDN line of 64Kb, • the HM an ADSL line, and the HFPVX a dedicated line of 512 Kb.
• These tests used a fast-ethernet communication line and an Internet Explorer 5.5 browser on an Intel with Windows 98 • The webserver was accessed through the hospital’s Intranet, using fast ethernet technology (100 Mbts/sg) and SSL
Table I Response of the system
