Caracterização elementar de filtros de alumínio de equipamentos de raios X odontológicos intrabucais

Abstract

The quest for radiographic quality with the lowest dose of radiation absorbed is a constant in the radiology community. Along with the ALARA principle (As Low As Reasonably Achievable), the aluminum filters are essential parts to bar the low energy photons do not contribute to the image and cause radiation dose to the patient. According to standard Portaria No. 453, the Agência Nacional de Vigilância Sanitária decreed that all equipment intraoral dental X-rays must have an additional filtration. Acording this, the filters are essential parts to radiological protection of patients. This study aims to characterize the elemental composition of filters used in intraoral X-ray equipment. We also intend to relate them to the quality of the radiographic images. The analysis of the filters was made using the method Energy Dispersive X-ray Fluorescence (EDXRF). Ten aluminum filters were analyzed (qualitatively and quantitatively). To evaluate the quality of images, 30 periapical radiographs of molars to 0.3 s (ten radiographs) and the incisor teeth 0.2 and 0.3 s (twenty radiographs) were performed with different filters. All filters and all radiographs were identified, it was possible to distinguish which folder each radiograph belonged at the time of the evaluations. All radiographs were performed under the same conditions. Radiographs were subjected to analysis of optical density by a densitometer and later, two dentists radiologists realized a subjective analysis. Three regions for analysis of the densitometer (differentiated between molars and incisors) and a region for subjective analysis (for different regions molars and incisors) were selected. The data were correlated with the assessment of the effects of the elemental composition of all filters in the quality of radiographic images. From the results, the elements of the filters in the analysis were: Al, S, Cl, Ti, Mn, Fe, Cu, Zn and Zr. The filters had higher aluminum concentrations (over 96%), other elements were contaminants or components that are added to improve the mechanical stability of the filter. The optical densities of radiographs followed a pattern for the regions analyzed except blackened regions of the film. Subjective analysis revealed that many of the radiographs were accepted for diagnosis. But considered low-contrast images obtained the same value of optical density. Therefore, it is concluded that the elemental composition of filters do not change the image quality. Consequently, conventional filters were evaluated option to produce an acceptable image quality in dental radiology, despite differences in the composition of the alloys.