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Biomedical subjects

Z Kolitsi

Publications and source records attributed to Z Kolitsi.

At least 19 recordsLinked to original sources
PubMed2001

Image quality in extended arc filtered digital tomosynthesis.

PURPOSE: To study image quality in filtered digital tomosynthesis (FDTS) tomograms as a function of their reconstruction arc, using isocentrically acquired, fluoroscopic projection data. MATERIAL AND METHODS: Both digital tomosynthesis (DTS) and cone beam CT (CBCT) reconstruction algorithms are based on backprojection and use cone beam projection data as input. Under limited angle conditions, CBCT is reduced to FDTS, where only a subset of projection data are used for reconstruction. The effect of the reconstruction arc on the spatial resolution, slice thickness, contrast sensitivity, shape distortion and artifacts, was also experimentally studied. The investigation was performed using both simulated and actual fluoroscopic images. RESULTS AND CONCLUSION: Image quality in terms of spatial resolution, slice thickness, shape distortion and artifacts, improved with increasing reconstruction arc and was optimized at 180 degrees, while contrast continued to improve as the arc was increased to 360 degrees. However, DTS was determined to be the technique of choice when reconstruction arcs of less than 40 degrees were used. Consequently, FDTS may be successfully implemented in applications involving extended arc reconstructions, in the range between 40 degrees delimiting the DTS domain and 360 degrees corresponding to CBCT.

Image Processing, Computer-Assisted↗
PubMed2000

A software data generator for radiographic imaging investigations.

A software data generation tool, intended to be used in radiographic applications, has been developed. The application integrates a phantom design module and an imaging simulator. Phantoms can be described as a set of either geometrical objects or voxels, or contours drawn on multiple tomographic slices. Radiographic projections of the phantoms are formed on the basis of a simulated irradiation process, with selectable imaging parameters. Comparison between actual projection images from a physical and a simulated phantom shows good correspondence. The application was used for digital tomosynthesis (DTS) investigations and has proven to be a useful tool in the study of tomographic noise. Further development is expected to expand the use of the application to more areas of radiological imaging research.

Algorithms↗
PubMed2000

Improving user acceptance of health-care telematics.

Telehealth represents a new approach to health-care with the potential for improving accessibility and reducing costs. Over the years, technology has become increasingly interactive, cheaper and standardized. Despite this, the uptake of technology has been low. One of the main reasons is that the introduction of telematics in health-care requires more than technology and software--organizational and cultural change is required as well. A suggested approach is based on the principles of service quality and quality management, to produce a partnership between the users and the developers of new technologies. This will in turn make it possible to bring user-validated requirements into the design of the system and create feelings of ownership and motivation on the part of users, in order to prepare their environment for the change. The methodology has been effectively used in various projects of the Telematics Application Programme of the European Commission.

Consumer Behavior↗
PubMed2000

Education in biomedical engineering: experience from a European ERASMUS program.

Based on recent advances in biomedical research and the developments of new equipment and techniques, the field of Biomedical Engineering and Health Care Telematics are currently undergoing a rapid evolution characterized by an increasing degree of specialization. This, in turns, imposes new requirements in advanced education, while the changing scene at European level, introduces a major challenge for harmonization and standardization of education with a focus on meeting the emerging needs. At the same time information technologies provide new means and tools supporting the educational and training activities. An initiative for the development of a multinational advanced course in Biomedical Engineering, is implemented in the University of Patras with extended collaboration of European Universities, providing a unique case for achievement of excellency. In order to take full advantage of this potential, a Quality Assurance system has been designed and implemented over the past four years, aiming to provide the appropriate framework for mutual recognition amongst the participating institutions. Additionally, the implementation of new telematic tools is scheduled for the near future, in order to provide the Course with teleconference facilities and allow a much larger number of students to remotely attend the lectures.

Biomedical Engineering↗
PubMed1999

An integrated system for the production of field shaping devices in radiotherapy.

A system has been developed in our department that simplifies the production processes of field shaping devices in radiotherapy, integrating an image grabbing and processing facility at a radiotherapy simulator and an automated block cutter. The data acquisition subsystem captures images, processes and corrects them for pincushion distortions, creates a composite radiograph, records user defined contours of blocks and exports data to the block cutter controller. A robotic subsystem drives and controls the polystyrene cutting unit. The system has been experimentally evaluated. Errors in contour definition were found to be less than 1 mm for a broad range of gantry angles and not exceeding 1.5 mm for those gantry orientations that present maximum magnetic field related image intensifier distortion, while the automated block cutter is capable of cutting out contours in polystyrene with an accuracy comparable to that of commercially available systems. The system is expected to contribute to the overall improvement of radiotherapy processes, particularly in low budget radiotherapy departments, introducing improvements in accuracy and efficiency at minimum costs.

Cost Control↗
PubMed1999

Three-dimensional localisation based on projectional and tomographic image correlation: an application for digital tomosynthesis.

Accurate three-dimensional tumor localisation in Radiotherapy, is critical to the treatment outcome, particularly when high dose gradients are present. A number of techniques have been proposed for the localisation of anatomical structures or markers. The present study proposes an approach to a concurrent maximisation of localisation accuracy and efficiency by correlation of tomographic and projectional images. The method introduces an element of direct verification and interactive optimisation of the process. Tomographic images are used for the identification of a point of interest. Its position is computed within the treatment co-ordinate system and verification of this position is achieved by obtaining the beam's eye view of the identified point on two projection radiographs. The key element of the approach is that all images used should be part of one single image data set. The implementation of this localisation method, as part of the functionality of a Digital Tomosynthesis prototype, has provided an integrated facility for localisation, of optimised accuracy and precision, while easy and efficient to use. The considerations are general and apply in principle to any imaging system that can augment tomographic images with projections.

Algorithms↗
PubMed1999

Monte Carlo simulation of the radiographic imaging procedure for electronically designed phantoms.

This paper presents a software simulation package of the entire X-ray projection radiography process including beam generation, absorber structure and composition, irradiation set up, radiation transport through the absorbing medium and image formation. This software tool is an augmented version of a previously presented system with expanded range of application by the implementation of Monte Carlo approach for the simulation of the radiation interaction at the absorber and the detector. Phantoms are created as composite objects from geometrical or voxelized primitives and can be subjected to simulated irradiation process. The acquired projection images represent the two dimensional spatial distribution of the energy absorbed in the detector and are formed at any geometry, taking into account energy spectrum, beam geometry and detector response.

Computer Simulation↗
PubMed1999

A protocol building software tool for medical device quality control tests.

Q-Pro is an application for Quality Control and Inspection of Medical Devices. General system requirements include friendly and comprehensive graphical environment and proper, quick, easy and intuitive user interface. Functions such as, a tool library for protocol design widely used multimedia, as well as, a support of a local database for protocol and inventory data archiving are provided by the system. In order to serve the different categories of users, involved in Quality Control procedures, the system has been split into three modules of different functionality and complexity, each of which can work as a stand-alone application. The implementation of protocols and use of the software functions, as well as, the user interface itself have been proved by the evaluators to be clear and intuitive. The software seems to adapt easily to different kinds of Quality Control procedures and objectives. Q-Pro effectively supports and enhances the processes to attain a highly tuned, professional, responsive and effective quality control and preventive maintenance procedures for biomedical equipment management.

Data Collection↗
PubMed1997

Quality assurance in conformal radiotherapy: DYNARAD consensus report on practice guidelines.

BACKGROUND AND PURPOSE: Conformal radiotherapy has only recently been widely implemented. Although not all aspects have yet been adequately proven, it is generally recognized that maintaining a high degree of precision throughout the process is critical to the treatment outcome while the focus for quality assurance and quality improvement will need to concentrate more on human factors, procedures, communication, organization and training. A general consensus document on quality assurance guidelines for institutions that deliver conformal radiotherapy treatments to patients has been elaborated within the framework of the DYNARAD/BIOMED concerted action on conformal radiotherapy. The present paper aims to highlight those issues that were identified as of specific importance to conformal radiotherapy. The work reported here further details this guidance by direct correlation with the issues involved in the special case of conformal radiotherapy. METHODS: The DYNARAD document has been drafted in the form of a desktop guide comprising six sets of guidelines and is based on the ESTRO advisory report on 'Quality Assurance in Radiotherapy'. RESULTS AND CONCLUSIONS: The document has been endorsed by the DYNARAD group of institutions. As such it can form the basis for further discussions and enter into the subsequent phase of expanding its consensus basis.

Consensus Statements as Topic↗
PubMed1996

Volume imaging in fluoroscopy. A clinical prototype system based on a generalized digital tomosynthesis technique.

PURPOSE: This work involves the development of a new digital tomosynthesis technique into a clinical prototype imaging system for the three-dimensional visualization of patient anatomy. MATERIAL AND METHODS: The multiple projection algorithm (MPA) has been developed into a clinical prototype imaging system comprising a digital chain that is interfaced with an isocentric fluoroscopic unit to form an integrated DTS facility. Planes of varying orientations can be synthesized retrospectively on the basis of an acquired set of appropriate projection images extending over the whole volume of interest. RESULTS AND CONCLUSION: The system provides an image reconstruction and processing facility that can effectively augment fluoroscopic examinations. Reconstruction times of a few seconds per plane have been achieved. The region of interest can be approached by tracking through cross-sections with user-selected orientations. Anatomical planes of particular interest can be identified and their reconstructed images can be stored. The characteristics of the image presentation modality have the potential to extend the field of current digital tomosynthesis applications to new areas in radiology and other clinical domains.

Algorithms↗
PubMed1979

Scattered radiation from beam modifiers used with megavoltage therapy units.

The magnitude and distribution of scattered radiation produced by scatterers inserted into megavoltage therapy beams, including the beams from an 8MV medical linear accelerator and a 60Co teletherapy unit, were investigated. The intensity distribution of scatter depends on the distance from the scatterer to the measurement plane (retraction distance) and also, to a lesser extent, on the atomic number of the scattering material. The effective energy of the scattered radiation was determined by depth dose measurements in tissue equivalent material using thermoluminescent dosimeters and was found to increase with photon beam energy.

Cobalt Radioisotopes↗
PubMedDate not supplied

An anatomical filter for exposure equalization in mammography.

An anatomical filter has been designed, tested and subsequently used in clinical practice to equalize optical density over the entire mammographic image, thus eliminating the need for dual exposure whenever both the mammary gland and the peripheral structures of the breast must be clearly visualized. The use of the filter results in a reduction of the optical density, at the peripheral structures of the breast, with a simultaneous increase of the contrast, without causing deterioration of the mammary gland image. Improved visualization of the connective tissue, the skin, the nipple and the subcutaneous adipose tissue is achieved, as well as minimization of the radiation dose to the breast for patients with an indication of peripheral breast lesions.

Female↗
PubMedDate not supplied

A wavelet-based method for removal of out-of-plane structures in digital tomosynthesis.

Reconstructed images in digital tomosynthesis (DTS) are affected by artifacts due to blur from planes other than the fulcrum plane. A wavelet-based method has been developed for the discrimination and subsequent removal of unrelated structures from the reconstructed plane. The approach exploits both the specific pattern of noise in DTS and the spatial locality of the wavelet transformation. The technique was implemented on a DTS clinical protoype system. Experimental evaluation on angiographic types of images demonstrated excellent noise differentiation and elimination. The method is therefore particularly useful for certain medical imaging applications such as vascular DTS imaging.

Angiography↗
PubMedDate not supplied

Q-Pro: a quality control management system for medical equipment.

Q-Pro is an application for quality control (QC) and inspection of medical equipment. The system has been designed on the basis of a broad requirements analysis, contributed by clinical engineers from several European countries and with a focus on current and forthcoming regulatory requirements concerning the quality control and risk management for medical equipment. Q-Pro comprises a generalized application, providing the necessary flexibility to accommodate the different degrees of difficulty and specialization in creating or customizing QC protocols, carrying out inspections and managing collected data. The system incorporates a tool library for QC protocol design, widely used multimedia as well as a local database for protocol and inventory data archiving. The paper presents a detailed account of the system context of use, design and functionality.

Equipment and Supplies↗
PubMedDate not supplied

Development of a new Clinical Engineering Management Tool & Information System (CLE-MANTIS).

The evolution of the field of biomedical technology has led to the diffusion of an impressive number of medical devices into healthcare institutions. In this environment, Clinical Engineering Departments (CEDs) are expanding their role in healthcare technology management, by changing their structure and introducing quality systems in order to improve their services and monitor the outcomes. In the framework of the national project BIOTECHNET II, a software tool for the management of biomedical technology, named CLE-MANTIS, has been developed, with the aim to assist CEDs in their tasks. CLE-MANTIS functions include the upkeep of an inventory, the support and monitoring of scheduled maintenance, corrective maintenance, vigilance, equipment acquisition and replacement, service contract management and user training. The system offers clinical engineers the possibility to monitor and evaluate the quality and cost-effectiveness of their departments through the monitoring of quality and cost indicators. This paper presents the main features and functions of the system.

Biomedical Engineering↗