Avaliação de parâmetros da qualidade de imagem e dosimetria de pacientes submetidos a exames radiológicos de tórax

• Ano de defesa: 2012
• Autor(a) principal: Paulo Marcio Campos de Oliveira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Ciências e Técnicas Nucleares; Tecnologia nuclear
• Link de acesso: http://hdl.handle.net/1843/BUBD-92WJN3

Optimization of procedures for obtaining high quality diagnostic images plays an important role for reducing radiation exposures of patients undergoing diagnostic radiology examinations to levels as low as reasonably achievable. Patient dose monitoring for different radiographic procedures has been used as a parameter to evaluate the performance of radiology services; skin entrance absorbed dose values for each type of examination were internationally established and recommended aiming the optimization for patient protection. In Brazilian institutions, a few studies for evaluating radiographic image quality have been done and there is a lack of criteria on the matter, except for mammography. This addressed the need and interest of using test objects and phantoms for large scale survey of the image quality in the region.In this work, internationally standardized radiation beams were implemented, characterized and applied for calibrating radiation detectors to be used for dosimetry of patients submitted to chest x-ray examinations. Absorbed dose in specific organs were determined by thermoluminescent dosimeters in an anthropomorphic Alderson Rando phantom and by the PCXMC® e CALDose_X Monte Carlo based softwares; disagreements found in the results were attributed to differences among the physical and mathematical characteristics ofeach phantom. An image quality evaluation methodology was studied and applied to one diagnostic service with a conventional chemistry film processing and two with a CR digital one. The image quality was evaluated based on European criteria and by means of the Fluke Biomedical Chest X-ray Phantom, Leeds TOR CDR Test Object and Gammex Radiographic Survey Phantom. Spatial resolution and high and low contrast used during postero-anterior (PA) and lateral (LAT) 9incidences. Data were collected from 200 patients related to 200 PA and 100 LAT incidences. Results showed that the image quality in the three diagnostic services was similar; the best relation between dose and image quality was found in the institution with the chemistry film processing. It is observed that there is room for dose optimization in the services with digital processing without reducing significantly the quality of the image. This work contributes for disseminating the radiation protection culture by emphasizing the need of a continuous evaluation of the technical procedures for optimized images.