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The use of the TL dosimeters for measuring inhomogeneities irradiation
CANDROVÁ, Daniela
Radiotherapy has commonly been utilised to cure cancer for more than a century. It is counted among the fundamental branches of medicine and represents an effective local or locally-regional method of curing both cancer and some non-cancerous conditions. It utilises ionising radiation which unfortunately eliminates tumour cells along with healthy ones. This is why a wide range of harmful effects of the radiation can be observed on humans. Patients treated with radiotherapy are in some cases monitored with dosimeters so that the intended dose can be compared with what is really absorbed. Nemocnice České Budějovice, a. s. monitors the dose in expected locations of non-homogeneous irradiation using the aforementioned TL dosimeters during the process of rotary irradiation of Mycosis fungoides. Before actually being used in an in vivo dosimetry, these dosimeters must be properly calibrated and have their sensitivity adjusted. Other than that, they are fairly easy to use, do not require much time or money invested and are able to constantly monitor the dose received by a patient treated with rotary irradiation. This diploma thesis discusses the usage of TL dosimeters to measure non-homogeneity of irradiation. It therefore compares the doses received by patients in various parts of the body during irradiation by the TSEI method. These 22 irradiated patients had thorough measurements taken of the doses they received in the so-called black hole region, their axillae and neck while holding their arms up and with arms loosely positioned close to the body. The thesis also suggests the possibility of the dosimeters being used by the integrated emergency service to assist during rescues and demolitions performed in emergency situations when a leak of ionising radiation occurs. Using TL dosimeters would mean more precise measurements of the dose received by the involved personnel in various parts of their body. If a patient is treated with the TSEI method, the dose received is monitored in a reference point, critical areas and areas with residual infiltrations or tumours. Doses measured in critical areas indicate that should the acral parts of limbs be left uncovered, they absorb larger doses than the rest of the body. They thus exceed the intended dose significantly. In the case of fingers, the dose tends to reach as much as 3 Gy. Depending on clinical picture, the attending physician determines whether special covering should be used. This covering reduces the doses received to merely a few tenths of a Gy. There also tends to be a large difference in absorbed doses in axillar areas and the neck, depending on whether the patient's arms are held up or close to the body respectively. Test results indicate that holding arms up or keeping them close to the body on a particular side have always had a profound effect on the dose absorbed by the patient in this particular area. This means that the position of the body greatly influences how much is absorbed in various parts of the body. TL dosimeters are also used in other areas than in vivo dosimetry in radiotherapy. An example of this could be determining the dose received in upper limbs of the workers monitored with thermoluminescent dosimeters in the form of bracelets or rings. They also serve to monitor the external irradiation of persons within the limits of the Czech Republic (TLD network). In radiation therapy, both the doses in skin and body are taken into account when conducting measurements. Depending on the data extracted, it is then possible to assess the course of treatment and ensure safe implementation of ionising radiation. Integrated emergency service teams deployed in cases of radiation emergencies are not considering using TL dosimeters so far, although they could most likely be used to ascertain the exact doses absorbed. Further research would however need to be conducted to either confirm or disprove the benefits of using TLD.
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Special access of the radiology assistant to interventional procedures in diagnostics of oncological patients
CANDROVÁ, Daniela
In my work I deal with the peculiarities in approach of a radiology assistant to interventions in diagnostics of oncological patients. Biopsy has a special importance in diagnostics of neoplasm. It is essential for histological and cytological diagnostics. The aim of this work was to find out the incidence of bioptic interventions on oncological patients during one year at radiology department at České Budějovice hospital plc, and to compare the advantages and disadvantages of used modalities. The work proceeds from the presumption that the number of interventions carried out under the sight control without the use of ionizing radiation methods is growing. In the theoretical part of my work appear descriptions of bioptic methods of intervention radiology regarding oncology and its methods, biopsies, screening methods used at biopsy (ultrasound controlled biopsy, computer tomography controlled biopsy, magnetic resonance controlled biopsy, skiascopic controlled biopsy), instrumentarium, especially the needles used for tissue extraction (puncture and bioptic needles), characteristics of oncological patients, the principle of tumour disease, carcinogenesis, oncologically changed tissue, and basic diagnostics of oncology disease. The practical part reveals the number of biopsies performed in 2012 at České Budějovice hospital plc, under computer tomography, ultrasound and mammography machine control, and the number of other interventions on oncological patients, namely localization of impalpable breast lesion, percutaneous drainage of the urinary tract under skiascopic control. Standard methods regarding these interventions and biopsies are described focusing on the advantages and disadvantages of their use for different organs in the body. I also described radiology assistant?s work and created photo documentation of given interventions. In 2012, 96 biopsies were performed under any of the mentioned diagnostic screening methods at radiology department of České Budějovice hospital. They represent 0,06% of the total of 171 466 diagnostic interventions at this department in the respective year. At the same time they represent 3,4% of the total of 2844 interventions of the ČB radiodiagnostic department of that period. From the whole number of 96 biopsies, 79% were performed on oncological patients. No biopsies were performed under magnetic resonance or skiascopic- skiagraphic control. Since the formation of a tumour is supposed to be the main somatic risk which an individual after a low intensity radiation faces, I supposed that the number of bioptic samples taken under sight control without the use of non ionizing radiation is rising, which significantly contributes to radiation protection. It is not univocally assigned which screening method is the best for biopsy. Usually we chose the biopsy that can screen best the site in different organs and that allows the safest, the fastest and the economically most convenient procedure. The chosen method should allow the doctor chose the site for sample extraction. The choice also depends on the habits and the technical equipment of given hospital. In view of the fact that according to this work computer tomography is the most commonly used method for bioptic extractions, and under magnetic resonance control no biopsies are performed, the prestige and importance of a radiology assistant grows up, because their presence at modalities using ionizing radiation is commonly indispensable. The hypothesis of my work has not been proved. Concrete results do not support the operative hypothesis of y work. However, I can recommend concessive long-term type and multicentrically elaborated sample studies. I would be grateful if this work provided an information base for radiology assistants´ training and for interventions in the diagnostics of oncologically ill people.
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