Karel Slavíček

A new approach to fully-reversible watermarking in medical imaging with breakthrough visibility parameters

Securing of medical images against intentional or accidental modification is a general issue in modern radiology. Watermarking, with its data-centric security, is very convenient for this purpose. We proposed a new method of fully reversible watermarking in medical imaging by combining the advantages of three traditional approaches—Reversible, Zero and RONI watermarking. The new method achieves exceptionally high values of Peak Signal to Noise Ratio and Structural Similarity index. The article evaluates the pros and cons of current methods of watermarking in medical imaging. Keeping the pros and eliminating the cons of the methods allows a new approach. Specific methods are selected and their application in practice described in detail. Application of the proposed method on a database of 6000 medical images from common hospital operations delivers very promising results which are discussed at the end of the article.

Mathematical Processing of Syslog Messages from Routers and Switches

The development of computer networks is very fast. Masaryk university in Brno owns and operates rather large metropolitan computer network. This network is based on fiber optics cable infrastructure owned by the university. Networking devices used in our universitys backbone network can send their log messages to a Unix-style syslog server. A syslog server accepts messages, and stores them to a file. The number of syslog messages generated by still increasing number of networking devices is growing very rapidly. To read all the messages generated every day by active networking devices is out of human capabilities. When we want to really process thousands of messages generated every day it is necessary to use some special software tools which help us to skip over messages containing mostly no information. Till now we are using software tool developed by a student of our university as a part of her master thesis. This tool is based on parsing of the syslog messages of known structure. This approach allows aggregation of messages reporting the same event and summarizing of repeating messages. This approach we can call semantic analysis of syslog messages. Nowadays we have probably reached limits of this system. The main limitation of this semantic based syslog analysis is the necessity of description of each event type i.e. knowledge of all messages describing this type of event. The system cant adapt to new condition like new routing or data transport protocols usage (e.g. IPv6). In this paper we describe mathematical methods we are trying to use for syslog messages processing. The goal was to find out some mathematical description of syslogging behavior which would allow us to check if the network behavior is usual or if it needs some special attention. The mathematical model of syslog should be adaptive and reflect possible structural changes in network equipment maintenance procedures, introduction of new protocols and smooth changes in network behavior. Mathematical processing of syslog messages seems to be perspective method for the future development of data networks.

Introduction of alien wavelength into Cesnet DWDM backbone

CESNET is an association of universities and Academy of science of Czech republic. It is operating a national research and education network (NREN) interconnecting all university cities in the republic. The optical transport backbone of this network is based on DWDM. Commonly used DWDM equipment are optimised for usage of transponders for connection of the user signal to transport network. For some particular applications we have utilised coloured signal and avoid transponders. Lab measurements and deployment of this solutions is described in the following article.

Integration of Telemedicine Activities in the Czech Republic

Institute of Computer Science of Masaryk University is working on the field of supporting medicine multimedia data transport archiving and processing more than ten years. Since first steps like transport of ultrasound and CT images across private fibre optics network these activities have grown up to regional PACS archive. Today more and more hospitals are participating on this project know under the name MediMed and we stand before scaling this project to republic wide application. Connection of remote hospitals introduced some not very common technical solutions. This paper describes current state of the art of MediMed project.

MEDIMED - Regional Centre for Medicine Image Data Processing

Masaryk University in Brno is operating a regional PACS archive serving to mostly all hospitals in Brno metropolis and a lot of remote medicine institutions. The communication between modalities (i.e. CT, ultrasound, X-ray, etc.) PACS archive and viewing stations is based on DICOM standard. This paper describes current state of the art of this medicine images storage system.

CESNET Fiber Optics Transport Network

This paper describes design and implementation of the optical transport network backbone of CESNET NREN. Both single-channel and DWDM technology are discussed. Uncommon technology solutions and the process of its implementation in CESNET backbone network is described. Paper is enclosed by description of the current CESNET DWDM topology and prospective development. The last part deals with analysis of optical channel protection capabilities of the core DWDM network.

PKI utilisation for PACS users authentication

Masaryk University in Brno is operating a regional PACS archive serving to mostly all hospitals in Brno metropolis and a lot of remote medicine institutions. For communication between modalities (i.e. CT, ultrasound, Xray, etc.) PACS archive and viewing stations is used DICOM standard. This standard was originally mentioned for usage inside one hospital so user authentication relays on IP address of viewing stations. This approach is not usable for communication between hospitals. In this paper we try to describe user authentication we are nowadays implementing in metropolitan PACS archive in Brno.

Maximum Frame Size in Large Layer 2 Networks

Ethernet protocol originally designed local area networks became very popular and in practice the only protocol used in local and metropolitan networks. Currently both IETF and IEEE are working on some improvements of this protocol to make it more attractive for usage in WAN networks. These modifications may add some additional fields into ethernet header so that the effective maximum transportable data unit will be decreased. From this point follows the problem how to inform upper layers about maximum data unit which ethernet layer can transport. This problem is not addressed in prepared IETF and IEEE standards. This paper tries to point out to this problem and propose some possible solutions.

Wireless Technology in Medicine Applications

Institute of Computer Science of Masaryk University is working on the field of supporting medicine multimedia data transport archiving and processing more than ten years. Since first steps like transport of ultrasound and CT images across private fibre optics network these activities have grown up to regional PACS archive. Today more and more hospitals are participating on this project know under the name MediMed. For deployment of MediMed to some remote locations and especially to residence users (medicine specialists) it was necessary to utilise wireless and microwave technologies. Experiences with usage of wireless technology for delivery of medicine picture data are described in this paper.

Redundancy in Processing of Medical Image Data

The Regional PACS (Picture Archiving and Communication System) Project, MeDiMed (Metropolitan Digital Imaging in Medicine), an advanced system for the support of processing of medical image information, started as a collaborative effort among hospitals in the city of Brno to process medical multimedia data. Masaryk University is the coordinator of this project ensuring that the demands and requirements of radiology departments are met and overseeing the changing legislative standards and the practical possibilities of technology. Masaryk University, in cooperation with CESNET (the Czech National Research and Education Network Operator), also provides the necessary network infrastructure. The open system described in this paper was, from the start, designed to serve also as a reliable and accessible communication node and as an educational and research tool available to any hospital or another healthcare institution, including medical faculties, that participated in the system. The regional system is designed as a combination of distributed architecture in terms of incorporated hospital data centres and centralized architecture as the image studies are continuously being sent to the long-term broadly accessible archive in the centre.