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Measurement of patients´ personal doses in radiotherapy outside the central beam of ionizing radiation using the electronic personal dosimeter
CHYLÍKOVÁ, Renáta
The introductory part of the diploma thesis primarily focuses on the history of radiotherapy, i.e. what it emerged from and how it developed, as it is one of the most important fields in medicine, especially because thousands of people are irradiated every day due to different tumour and non-tumour diseases. Another reason why ionizing radiation is described is the fact that it is a necessary part of tumour disease irradiation. Ionizing radiation is also connected with radiation protection. This section presents a historical overview of radiation protection, as well as principles and quantities of this field. Furthermore, it focuses on Czech acts, decrees, and government regulations which define various measures governing this issue. Radiation protection forms the basis of patient, workplace, and personnel monitoring. All this is connected with the measurement and evaluation of received personal doses. This brings the thesis to the field of dosimetry, therefore various dosimeters used in practice are described. The aim of this diploma thesis is the measurement of patients? personal doses in head and neck irradiation using the electronic personal dosimeter at the radiotherapy centre of Nemocnice České Budějovice, a. s. The thesis is based on the question of whether irradiation doses that patients with head and neck tumours receive outside the primary radiation beam are negligible. The theoretical part of the thesis uses all available resources from both foreign and Czech literature. The practical part is based on numerical statistics, i.e. a quantitative method. The research was carried out at the radiotherapy centre of Nemocnice České Budějovice, a. s. Irradiation of patients with head and neck tumours was performed on a linear accelerator. Each patient had a mask to which an electronic personal dosimeter was attached during irradiation. Using this dosimeter, it was possible to measure doses received outside the central radiation beam. The measured values were then used to carry out assessment using formulas. Patients who undergo cancer treatment receive relatively high doses of radiation, so my main goal was to measure personal dose equivalents at the reference point. When comparing the percentage of the number of examinations with the web portal Epidemiology of Malignant Tumours in the Czech Republic, it was found that irradiation of the neck is more frequent than irradiation of the head. The total values of personal dose equivalents are relatively high in each patient, but because it is medical treatment, these values are not subject to radiation exposure limits. The comparison of the irradiated areas shows that irradiation of the neck has small values of personal dose equivalents to 1Gy compared to irradiation of the head.
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High resolution computed tomography - its role and position in radiodiagnostics
CHYLÍKOVÁ, Renáta
In the introduction to my bachelor´s thesis, I have described the historical background of HRCT, its origins, and evolution. The historical part includes information about the development of CT equipment and the principles of diagnostics using the instruments that preceded HRCT. In the following part, I have described the principle of how HRCT works and the conditions that are needed for HRCT examination. I focused on lung examination and partly also on the examination of temporal bone. The objective of my thesis is to determine the frequency of CT and HRCT application, for the purposes of which I compared two leasing hospitals in the South Bohemian region. I issued from the hypothesis of a higher frequency of HRCT use. In my bachelor´s work I used foreign literature and sources and also the method of comparing data from two hospitals. The preferred method was the quantitative one, used for numerical statistics in the theoretical part; for the practical part I used the mentioned comparison of the number of examinations performed at two hospitals in South Bohemia. When confronting the two hospitals, a significantly higher frequency of HRCT use was found in Nemocnice Tábor a.s. This fact is explained by the use of Aquilion 16, which is a lower ? quality appliance, and Aquilion 64 in České Budějovice, as well as by the monitoring of patients with fibrosing processes (so ? called cordarone lung, etc.), and patients with unclear small lesions appearing on summing images when only HRCT examination was performed. HRCT is also performed as a part of routine examination of the lungs and mediastinum if the indication requires it, while check ? up examinations run only under the HRCT algorithm. In conclusion it can be stated that the difference between the examinations in hospital České Budějovice a.s. and Nemocnice Tábor a.s. is based on the difference between their equipment and also the slightly different approach to small lesions in the pulmonary parenchyma.The hypothesis that the HRCT examination is used more frequently than the common CT examination of the lungs and mediastinum was not confirmed, which results from the fact that the number od patients needing the examination of just small or larger changes in the pulmonary parenchyma is substantially lower than the number of patients with indicated classical examination of the lungs and mediastinum.
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