Avaliação dos Filtros de Rh e Ag na Qualidade de Imagem e Dose em Mamografia

Current mammography systems have automatic exposure control based only on breast thickness and not on anatomy and composition. However, the breast tissue has structures that have very similar radiation attenuation coefficients. These studies are needed to obtain optimized acquisition techniques, so that it results in an image with quality and lowest dose possible for the patient. The objective of this work is to compare W/Rh and W/Ag combinations and to evaluate their influence on image quality and mean glandular dose (DGM). For this study, eight images of one were acquired using an anthropomorphic phantom, four with the W/Rh combination and four with the W/Ag combination, in a Hologic FFDM equipment, model Selenia Dimensions. The voltages used were 28, 30, 32 and 34 kVp and an ionization chamber was used to obtain DGM. The CNR and SNR were calculated using ImageJ software. DGM was lower for the W/Ag combination in all acquired images. The evaluation of the image quality considering only the SNR, for the two combinations, presents similar behavior, however, when considering the CNR, the combination W/Rh presents a considerable increase in the images acquired with lower voltage. Dose reduction with the W/Ag combination can be achieved on images acquired at higher voltage.