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Monitoring the effects of new exposure parameters after transition to CR digital image processing in the Radiodiagnostic Department at Sušice Hospital, o.p.s.
KLIMENT, Karel
At the current time, doses of radiation caused by medical exposure make up the largest part of peoples' exposure to artificial sources of ionising radiation (SIR). Every medical exposure must be justified as of benefit to the individual subject to it. Radiation protection at the workplace is subject to the principle of optimisation. One of the paths leading to optimisation of radiation protection is the specification of the Local Diagnostic Reference Level (LDRL). The objective of this thesis was to test and evaluate whether and how transition to indirect digitisation affects image quality. According to model examinations on a water phantom, the lowest possible dose for which image quality would be preserved was to be determined. If the dose could be reduced, it would be possible to specify a new LDRL. The dose can be reduced, amongst other things, by making appropriate adjustment to exposure parameters on the control unit. I tested how changes in the exposure parameters set affected the quality of the resulting image. I used the water phantom for each examination which corresponded to the thickness of the area to be examined for a standard patient. For constant default voltage, first of all changes to the settings were made to reduced blackening and increase electrical charge. Subsequently, voltage was increased and reduced with a constant blackening level. Image quality was evaluated according to the measured values for noise, and high and low contrast resolution. I used the results to determine recommendations for specific examinations in terms of exposure parameters to be set. I worked out the LDRL for the new exposure parameter settings and compared it to the current LDRL values at the workplace and with the NDRL (National Diagnostic Reference Level).
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Methods of checking the observance of diagnostic reference levels in the field of radiodiagnostics
KROUPOVÁ, Helena
Methods of Checking the Observance of Diagnostic Reference Levels in the Field of Radio diagnostics Although there is a simultaneous development of diagnostic and therapeutic methods, perfection of instrumentation and means for personnel and patient protection, there is also an effort to reduce applied doses. In this way, medical irradiation caused by ionizing radiation used in medicine represents a significant contribution to the total dose of ionizing radiation that a person is exposed. Today the medical radiation in the Czech Republic comprises more than ninety per cent of radiation from an artificial source and approximately one ninth from the total population radiation. Evaluation of professional doctor radiation and X-ray devices attendance has been safeguarded within the personal dosimetry for many decades. However, systematic monitoring of doses related to medical radiation of the patient is a relatively new problem in the radiodiagnostics sphere. According to the Council directive 97/43/EUROATOM requirement, the SUJB has stated the so called ``diagnostic reference levels{\crqq} within enclosure number 9, Regulation No. 307/2002 Coll., about radiation protection. These ``diagnostic reference levels{\crqq} are dose levels within medical radiation and their exceeding is not expected at the 70 kg adult patient medical examination in the case of correct practice. The systematic exceeding of diagnostic reference levels under clinical practice conditions is the reason for reconsideration of radiation protection optimalization at a given workplace. In accordance with the proposal of the National Radiology Standards for Radiology Physics, the author team recommends the monitoring extension of the patient radiating load related to a particular medical radiation by specifying the local diagnostic reference levels, typical for a given type of workplace at a particular keeper, and their continuous verification within the clinical examination of the standard group of patients. Generally, the doses can be determined in two ways: by exposure parameter calculation or by product measure of area kerma, which is generally implemented by special devices, so called DAP meters. The aim of the work is the description of both methods, their comparison and the evaluation of the method effectiveness at various types of sciagrammatic workplaces.
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