Estudo de otimização de sistemas mamográficos utilizando FOM (Figura de Mérito)

Abstract

Mammography is the most effective way to identify breast cancer. As the breast tissue has similar X ray attenuations, the image must have a good contrast so that it is possible to distinguish healthy tissue from lesions. But a consequence for good contrast is the increased dose in the patient. With this, it is necessary that the mammographic system be optimized, that is, it must have the best image quality, which is a great contrast for the lowest dose. The optimization of the system can be evaluated through a metric that considers the dose received by the patient and contrast of the image, called Merit Figure, which can be expressed as: 𝐹𝑂𝑀= 𝐶𝑁𝑅2𝐷𝑒𝑝. FOM is used for the normalization of dose effects, and the higher the value obtained the better the system optimization, that is, it has the highest possible contrast for the lowest acceptable dose in the patient. With these considerations, the objective of the work is to evaluate two FFDM mammographic systems installed in public reference services in the city of São Paulo. The images were simulated in the equipment through the phantom CIRS 011A, and the analysis was performed in the IMAGEJ® software, in which regions of interest were selected to perform the calculations. Analyzing the results, the amount of Glandular Dose and DEP were within normalities, as well as the FOM value, which had a satisfactory result. Regarding optimization, the mammographic system of UNIFESP presented a better optimization.