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Optimization of the Radiological Protection in Diagnostic X-ray Examinations
GREGOROVÁ, Tereza
This thesis deals with the topic of optimization of radiation protection of patients at a radiodiagnostic workplace. It discusses the possibilities of protecting patients from X-ray radiation in radiodiagnostics, both by technical parameters that can influence the dose and by the use of protective shielding, both in the primary radiation beam and outside it. In the practical part I focused on the calculation of diagnostic reference levels for selected examinations. Examination data was obtained from the DICOM header from the Dicompass viewer. For the calculation, I chose the chest examination in PA projection and the skull examination in AP projection lying on the examination table. Exposure parameters from three stationary scanners on which both selected examinations are currently routinely performed were analyzed. The observed values of input surface kerma and surface kerma for each scans were compared with the values of local diagnostic reference levels and with the values of national diagnostic reference levels. There are no national diagnostic reference levels for pediatric examinations, so I used the 2015 European Guidelines on DRLs for Pediatric Imaging document, which contains diagnostic reference levels for pediatric patients, to compare the values. The content of this paper can serve as a basic overview of optimizing radiation protection and calculating diagnostic reference levels for healthcare professionals and the general public.
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Evaluation of the clinical results of in-vivo dosimetry in oncology in České Budějovice
ČAJANOVÁ, Nikola
Today radiotherapy or treatment using ionizing radiation effects is one of the main methods of treatment of oncological diseases. Sufficiently high doses of ionizing radiation are able to inactivate and kill cancer cells. The surrounding healthy tissue, however, these effects of radiation is harmful. The strategic aim of radiotherapy is the removal of tumor bearing the least damage to the surrounding healthy tissue. The task of the radiotherapy is to find the optimum compromise between these two conflicting requirements. Radiation treatment planning is a very lengthy and complex process. It should be precisely executed, in order to maintain the highest efficiency and safety of the treatment. The destination volume identified by the radiation oncologist must be using various imaging techniques (CT) exactly localize before start the exposure. It is also necessary to make the determination of the size of the individual and the total dose, fractionation, irradiation conditions, the size and arrangement of irradiation fields, etc. The entire planning process is the need to constantly verify. Verification is carried out during the planning of the patient, irradiation conditions (System verification), the target volume (verification) and verification of dose (measurement) to ensure the highest quality of radiotherapy. Ensuring quality in radiotherapy deals with international Quality Assurance (QA), which by law must have each of the departments of radiation oncology in the Czech Republic drawn. This program defines the procedures to be followed in order to eliminate all inaccuracies that could lead to sub-optimal treatment of radiation excessive or insufficient exposure. One of the tools for QA in radiotherapy is also the in-vivo dosimetry, which is the main subject of this Bachelor's study. Part of the verification system, and as the last fuse QA throughout the algorithm of radiation treatment is in-vivo dosimetry. Using this technique, measure input and output radiation dose in terms of in-vivo, i.e.. directly on the patient. The measurement shall be verified, that the scheduled dose agree with a dose of radiation. In-vivo dosimetry is performed on radical cancer patients during external radiation on a Linear Collider. The radiation dose is detected by using semiconductor diodes or termoluminescent materials. In-vivo measurement is not only to control the dose delivered to the target volume, but also absorbed dose in critical organs or in situations where it is difficult to predict the dose. Through the in-vivo dosimetry in time can reveal various system inaccuracies or random errors for individual patients. To detect incorrect radiation doses are used tolerance limits. When exceeding the limits it is necessary to perform a detailed inspection of all steps of the radioterapeutic process. To get acquainted with the issue of in-vivo dosimetry and its representation in the current radiotherapy was handled by the theoretical part of the Bachelor´s thesis with the use of specialized information sources...
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The feasibility of different biodosimetric methods for dose estimation in case of radiation accidents.
PAVEZKA, Luboš
A deterioration of the coincidental hazards linked to the use of ionizing radiation is currently observed for four reasons. First, the increasing demand for radiation sources in numerous industrial applications (food sterilization, construction, engineering) leads to an increasing likelihood of loss of the sources or abnormal/unsuitable use and storage. Second, advances in medicine generate new protocols and tools that are more efficient but also much more complex to execute, increasing the risk of accidental overexposure. Third, the possibility of a terrorist attack using radiological or nuclear devices has to be taken into account. Finally, recent events in Fukushima (Japan) highlight the risks of exposure in the case of nuclear power plant accidents. All these issues could lead to the accidental exposure of one to several thousand individuals not wearing dosimeters. Thus, it is essential to be able to assess the exposure level of victims. Nowadays, this evaluation is based on clinical diagnosis (mainly irradiation symptoms and hematological variations) supplemented with biological dosimetry andphysical dose reconstruction. Biological dosimetry is especially important when the personal dosimeter is lacking or when the accidental context is unclear. All this information should help the medical staff to deliver appropriate medical care and to manage the long-term medical follow-up, if required. To fulfil this task, the dose estimates has to be timely, exact and conclusively reached in large-scale disasters. In my bachelor thesis, I have focused on the applicability of the various techniques for different scenarios: small- and large-scale exposes to different levels of a radiation that could manage to the urgent radiation syndrome and exposures with lower doses that do not need direct care, but should be followed for evidence of long-term impacts. The principle of biodozimetry is to utilize changes caused in the individual by ionizing radiation to estimate the dose and, if feasible, to predict or reflect the clinically relevant reaction. Optimally, the changes should be specific for ionizing radiation, and the response should be unaffected by prior medical or physiological variations among subjects, including changes that might be caused by the stress and trauma from a radiation event. There are two basic types of biodozimetry with dissimilar and very often complementary characteristics: those based on changes in biological parameters such as gene activation or chromosomal abnormalities and those based on physical changes in tissues. Factors advised comprise: time interval when the assay is feasible biologically, time for sample preparation and analysis, dose finding limit, ease of use, logistical demands, potential efficiency, point-of-care eligibility, and the ability to support patient diagnosis and treatment within a therapeutically relevant time point. The development of of biodozimetry has been mainly encouraged by the needs after a large-scale accident, where it is essential to have a tool or device to identify those individuals who would profit to be brought into the medical care system.
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Monitoring of radiation stress of pacients during radiographic examination in FNKV Prague
SEDINOVÁ, Monika
Abstract In my Bachelor´s thesis I dealt with the X-ray burden to which patients were exposed during the skiagraphic examination at the Radiodiagnostic Clinic of the Královské Vinohrady Teaching Hospital in 2008 and 2009. The goal of the thesis was to optimize the dose of X-rays during skiagraphic examination, while maintaining the highest possible quality of the skiagram, and to propose an optimum solution in terms of the control of exposure of the population. I have tried to compare the radiation burden on the patients in analogue and digital skiagraphy using standart protective aids, and to analyze the radiation burden on the patients during skiagraphic examinations. Calculations partly confirmed the hypothesis that the radiation burden on the patients may be reduced not only by setting appropriate exposure parameters, but mainly through different image systems and their optimization
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Reduction of radiation exposure by the use of the fluoroscopic spinal navigation system during the transpedicular screw placement of the lumbal spine.
ŠRŮTKOVÁ, Eva
RADIATION EXPOSURE REDUCTION BY THE USE OF FLUOROSCOPIC NAVIGATION IN TRANSPEDICULAR INSTRUMENTATION OF THE LUMBAR SPINE SUMMARY The topic of this thesis is a comparison of radiation exposure during standard fluoroscopy and navigated transpedicular instrumentation of the lumbar spine, in compliance with standard techniques and accuracy of screw placement. Material and the Method: A group of 60 patients, divided into two equal groups, was statistically processed. In the first group 1.9 lumbar spine segments were stabilized. The patients´ average age was 60.8 years (from 35 to 75 years). Screws were inserted transpedicularly under the X-ray image intensifier navigation. In the second group stabilization of 1.8 segments was performed on average. The average age was 61.1 years (from 38 to 75 years). The screws were inserted postoperatively by using 2D fluoroscopic navigation technique (VectorVision, BrainLAB, Germany). The duration of skiascopy was collected from the X-ray image intensifier and recorded for each surgery (with navigation and without). The measured values were compared with each other. In both groups the screw positioning was checked continuously according to the rules defined by Learch, Acikbas and Whitecloud in the anteroposterior and lateral projection by meticulous pedicle palpation Results: The radiation exposure was calculated to one vertebra (2 screws) in both groups. In the second (navigated) group the radiation exposure time was significantly shorter (3.4 s) than in the first (standard) group (14.4 s). The mean duration of data registration was 6.0 minutes (range 3 to 11 minutes). The mean ratio according to Acikbas's calculation method was 43.2 % (range 32 % to 74 %) in the first group and 44.1% (range 35% - 76%) in the second group. The mean exposure dose of the first group was 243 ?G/m2 and 138 ?G/m2 in the second group. Exposition doses are smaller by 105 ?G/m2 in the second group Conclusion: Based on the results, the hypothesis that navigation allows the same accuracy of pedicle screws insertion while reducing radiation exposure of the patients and the operating room staff to about ? can be confirmed. This reduction is more pronounced in multiple-level spinal stabilizations and in the centers for spinal surgeries, where numerous spinal instrumentations are performed every day.
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Digitization, the advantages and disadvantages, compared with analog processing of X-ray method with respect to radiation dose
TONCROVÁ, Silvie
Many years have passed since the discovery of X-rays, and yet X-ray examination remains one of the most frequently used examinations today. During the course of existence of radiological science, high-performance X-ray machines have been developed for basic radioscopy and radiographic techniques. In recent decades, computing technology has been increasingly applied in X-ray devices, and has become the basis for new X-ray examination techniques, introducing digitalization to the field of X-ray diagnosis. The objective of my work is to compare the advantages and disadvantages of digital processig of X-ray images versus analogue techniques, and to compare the economic and operational costs of these systems and the doses used in the respective devices. The comparisons were made at departments and units equipped with systems of direct digitalization, indirect digitalization, and analogue image processing. My hypothesis that the use of digital devices entails a lesser radiation burden for patients was confirmed. This is well apparent from the tables and graphs documenting the results of my measurements. I also provide a basic description of the generation and processing of X-ray images using the respective systems, some legislative requirements, and an explanation of basic terms and technicals data about the diagnostic devices used. This work indicates that digitalization in the field of radiodiagnostics contributes to the reduction of radiation dose for patients and is more economical for major healthcare facilities. Digitalized systems place greater demand on the software for image creation, but when properly used, they facilitate and expedite the work of radiology assistants and improve the quality of patient care.
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Monitoring and comparison of radiation dose of patient and physician during examination of brain arteries with single plane (conventional) digital subtraction angiography (DSA) and biplane DSA
SLAVÍKOVÁ, Jana
In experimental part I deal with measurement of radiation dose of the staff and patients in angiography examination of brain arteries.I compare the measurements with the use of single plane and biplane DSA and radiation dose of patients. The measurement was carried out with Siemens Axiom Artis Biplane machines at radiodiagnostic department in"Na Homolce"hospital. For the calculation of dose the programme Effdose version was chosen. I also compare measurement in physicians during angiography examination at radiodiagnostic department in České Budějovice hospital and in {\clqq}Na Homolce" hospital in Prague. For these purposes electronic personal dosimeters EPD Mk2 ( Siemens firm) were used. All results were worked out into graphic charts for better clarity.In the end of my work the proposals and measures, how to reduce radiation dose which is necessary in these angiography examinations, are described.
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