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The radiation exposure of the employers in Jachymov Spa
STRAKOVÁ, Eliška
Jáchymov radon spa, which is the subject of this bachelor thesis, uses, besides classic spa methods and balneological procedures, the radon water treatment. The main goal of this thesis is to get familiarised with the spa and empirically evaluate radiation exposure of spa employees. In the theoretical part, I define (theoretical basis) basic concepts, on which the problematics of this thesis is based. In another part I deal with the history of the spa complex, origin of therapeutic sources and their utilization. Also, as a part of this thesis, I mention illnesses, indicated for this type of treatment and clarify principles and effects on the basis of documentable research from literary sources. Because the thesis is focused on radiation exposure, in other chapters I deal with radiation protection and monitoring of doses (of radiation) of staff present in the spa. Practical part is focused on empirical quantitative research, aiming at statistical processing of data for development monitoring. The main idea is to process radiation exposure of employees in the timeframe of 26 years, between years 1991 - 2016. Furthermore to evaluate the development with closing general comparison of the processed results between spas, utilising radon water treatment and employees of uranium mines. Statistical processing shows that development of received doses is periodically fluctuating. The average value of effective dose was found to be 2,39 mSv in all employees with the highest possible received dose of 10,23 mSv per year. In case of equivalent dose to the skin was the average value 1,70 mSv per year. Despite the dose values being fairly high, it can not be said that radon spa employees exceed limits of radiation protection.
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The comparison of plastic scintillation detector with detector NaI(Tl), their utility and dosimetric properties. 1. The plastic scintillator detector 2. NaI(Tl) detector
VÁVRA, Jiří
This bachelor thesis deals with ionizing radiation, especially with its detection by another name measurement, in two scintillation detectors of ionizing radiation, a plastic scintillation detector and the detector of thallium-activated sodium iodide by another name NaI (Tl). The first description of an ionizing radiation in general terms is in the first chapter, eg. what is ionizing radiation and radioactivity, types of radioactive decay are listed and explained, further there are explained the interaction of ionizing radiation. Subsequently there are shown the passage of ionizing radiation by the material and in shortly way sources of ionizing radiation. Then there are quantities and units characterizing the radiation field in the space and the radiation exposure to the substance. As I do not deal with the effects of ionizing radiation on the organism in my bachelor thesis, there are not listed quantities and units associated with it. After information about ionizing radiation there is general information about scintillation detectors, which ideal properties should have scintillation material, the principle of scintillation detectors. In particular, there are information about mentioned detectors and their properties. The aim of the thesis is to compare the plastic scintillation detector with the detector NaI (Tl), which are used very often nowadays. Then to compare functional characteristics of these detectors, which are used in dosimetry, in industry, healthcare, and others. Then to compare efficiency, resolution, energy dependence, etc. with using the measurement of point emitters. There were used to measure the detectors of the same size for effective comparison, then radionuclide sources emitting the ionizing radiation with different energies in the entire measurement range. All measurements were made over a sufficiently long period and in the lead shielding to avoid interference from other (natural) radiation. The resulting spectras are indicated by peaks of the radionuclides to be a distinct difference in the resolution at used detectors, then there is graphically illustrated the light yield of detectors. I performed the energy calibration of both detectors, the efficiency calibration of the detector only at NaI (Tl) detector. It was not possible to implement this calibration at a plastic detector mainly due to the bad resolution of the detector and the resulting lack of calibration points. This problem has resulted that the energy calibration curve is not linear at a plastic detector; therefore, it is not entirely optimal. Both formed curves are essentially ideal at the detector NaI (Tl). It is shown from the measured spectras and their evaluation that the detector NaI (Tl) has a significantly better resolution and better light yield. So why and for what to use a plastic scintillator detector? The fact is discussed at the end of this thesis. Although plastic detectors have low spectrometric properties, they are used very often. Mainly because they are several times cheaper and they can be produced in large sizes and different shapes for a reasonable price. They are used for quick selection, thus determining whether the measured object emits ionizing radiation or not. NaI (Tl) detectors are used to identify radionuclides because of their relatively high resolution.
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RADIATION PROTECTION OF PATIENT WITH USING INTENSITY MODULATED RADIOTHERAPY (ImRT) {--} DOSIMETRIC VERIFICATION OF TREATMENT PLAN.
KLEČKOVÁ, Naděžda
Nowadays more and more radiotherapy departments use intensity modulated beams for treatment of patients. Intensity modulated radiotherapy (ImRT) is able to modificate intensity of radiation across the iradiated field. In this way it is posible to achieve better dose conformity than in conventional radiotherapy. Implementation of ImRT allows us to escalate dose to target volume with same side effects of organs at risk as in conventional radiotherapy or to reduce normal tissue complication - decrease dose to organ at risk with the same tumour dose. This fact reguires extension of our guality system to all network of delivery dose to patients, inclusive linear accelerator with multileaf collimator, treatment planning system, electronic portal imaging device and so on. Quality assurance is guaranteed both periodical user tests and independent verification of The State Office for Nuclear Safety. The aim of this work is finding the optimal and effective way for the verification treatment plans, determining criteria for evaluation measured results, proposing summary all aspects of radiation protection patients which are treate ionisation beams with intensity modulated radiotherapy. The optimization one of the principles of radiation protection will be provided by routin verification treatment plans.
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