The air kerma area product PKA is an important quantity used by hospital physicists in quality assurance and optimization processes in diagnostic radiology and is recommended by national authorities for setting of diagnostic reference levels. PKA can be measured using a transmission ionization chamber (kerma area product (KAP) meter) mounted on the collimator housing. Its signal QKAP must be calibrated to give values of PKA. The objective of this thesis is to analyze the factors influencing the accuracy of the calibration coefficients k= PKA/QKAP and of reported PKA-values. Due to attenuation and scatter in the KAP-meter and presence of extra-focal radiation, values of PKA depend on the choice of integration area A and the distance of the reference plane from the focal spot yielding values of PKA that may differ by as much as 23% depending on this choice. The two extremes correspond to (1) PKA=PKA,o integrated over the exit surface of the KAP-meter resulting in geometry independent calibration coefficients and (2) PKA=PKA,Anom integrated over the nominal beam area in the patient entrance plane resulting in geometry dependent calibration coefficients. Three calibration methods are analysed. Method 1 aims at determine PKA,Anom, for clinical use at the patient entrance plane. At standard laboratories, the method is used to calibrate with respect to radiation incident on the KAP-meter. Problems with extra-focal and scattered radiation are then avoided resulting in calibration coefficients with low standard uncertainty (±1.5 %, coverage factor 2). Method 2 was designed in this work to approach determination of PKA,o using thermoluminescent detectors to monitor contributions from extra-focal radiation and account for the heel effect. The uncertainty in derived calibration coefficients was ± 3% (coverage factor 2). Method 3 uses a Master KAP-meter calibrated at a standard laboratory for incident radiation to calibrate clinical KAP-meters. It has potential to become the standard method in the future replacing the tedious method 2 for calibrations aiming at determination of PKA,o. Commercially available KAP-meters use conducting layers of indium oxide causing a strong energy dependence of their calibration coefficients. This dependence is investigated using Monte Carlo simulations and measurements. It may introduce substantial uncertainties in reported PKA– values since calibration coefficients as obtained from standard laboratories are often available only at one filtration (2.5 mm Al) as function of tube voltage or HVL. This is not sufficient since higher filtrations are commonly used in practice, including filters of Cu. In extreme cases, calibration coefficients for the same value of HVL but using different tube voltages and filtrations can deviate by as much as 30%. If standardised calibration methods are not used and choice of calibration coefficients not carefully chosen with respect to beam quality, the total uncertainty in reported PKA–values may be as large as 40-45%. Conversion of PKA-values to risk related quantities is briefly discussed. The large energy dependence of the conversion coefficients, ε/PKA, for determination of energy imparted,ε, to the patient reduces to a lower energy dependence of calibration coefficients CQ,ε = ε/QKAP for determination of ε from the KAP-meter signal.

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Made available in DSpace on 2014-10-09T12:27:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:06Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:33Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:06Z (GMT). No. of bitstreams: 0 / Foram estudadas as respostas de 76 detectores Geiger-Müller, 4 detectores semicondutores e 34 câmaras de ionização. Muitos deles foram calibrados em feixes de radiação gama (37Cs e 60Co) e alguns foram testados em feixes de radiação beta (90Sr+90Y e 204Tl) e X (N-60, N-80, N-100, N-150). Para os três tipos de radiação, foram obtidos os fatores de calibração dos instrumentos e foi estudada a dependência tanto energética como angular destes detectores. Para radiação gama e beta foi estudada a dependência angular para ângulos de 00 e ± 450. Foram ainda obtidas as curvas da resposta dos instrumentos em relação a uma varredura angular de 00 e ± 900, para radiação gama, beta e X. Também foram analisados os fatores de calibração obtidos para radiação beta em relação à radiação gama. Para radiação gama, dos 66 detectores Geiger-Müller estudados, 24 apresentaram resultados para a dependência energética de acordo com a recomendação internacional da ISO 4037-2 e 56 estão de acordo com a recomendação brasileira da ABNT 10011. As câmaras de ionização e os semicondutores estão de acordo com as recomendações nacional e internacional. Todos os instrumentos apresentaram dependência angular menor que 40%. Para radiação beta, os instrumentos apresentaram resultados insatisfatórios para a dependência energética e angular; Para radiação X, as câmaras de ionização apresentaram resultados para dependência energética de acordo com a recomendação nacional, e a dependência angular foi menor que 40%. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Diploma thesis describes situation of Russian federation as an energy power. It is concerned with relationships of EU and Russia, especially with the distribution of russian energy resources to Europe. It describes projected gas pipelines, which do not cross the territory of Ukraine. Thesis analyses European union dependence on energy supplies (especially gas supplies) from Russia and is concerned with the question of Energy security. In the thesis there are introduced both relationships of Russia and EU (one subchapter is devoted also to relationships of Russia and Czech republic) and relationships of Russia and China -- rising and rapidly growing economy which needs a lot of energy resources to its growth, therefore China increases its energy demand and turns its interest to Russia. The main contribution of the thesis is conducted analysis of the situation of Russia as energy power and analysis of russian relationships with Europe (and china) and mentioned solutions of EU-Russia dependence on gas supplies.

The aim of the diploma thesis is to analyze People's Republic of China and India from the point of view of their mineral and energy dependence, where mineral means the necessity to import raw materials for the industry, while energy corresponds to imports of energy resources, namely coal, oil and natural gas. The secondary aim is so called 3C-Analysis (Comparison, Competition, Cooperation), which compares these two economies and evaluates their mutual relationships. The thesis is divided into three main parts - China, India, 3C-Analysis. The subchapters focuse on partial analysis, which are the definition of strategic minerals based on the key industrial branches, the determination of causes of mineral resources dependence and problems outcoming from current structure of energy imports, as well as the analysis and evaluation of the steps leading to the dependence elimination. The text also contains information about the situation in industrial and energy sector of both countries and basic data of raw materials production, reserves, consumption and imports.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19820号 / エネ博第326号 / 新制||エネ||66(附属図書館) / 32856 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 宇根﨑 博信, 教授 石原 慶一, 教授 手塚 哲央 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

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