Simulação Monte Carlo de mamógrafos para determinação da Dose Glandular Média, para diferentes combinações anodo/filtro dos tubos de Raios-X

Abstract

Mammography plays a crucial role in detecting breast cancer. In several places, Computed Radiography (CR) and Direct Radiography (DR) are still used. However, the latest technology is the digital breast tomosynthesis (DBT) system, which employs a sequence of acquired projections onto the breast. In quality control for X-ray mammography, there are no standard protocols for 3D breast imaging dosimetry, along with considerable output in X-ray spectrometry. Furthermore, it is necessary to evaluate the Mean Glandular Dose (DGM) using polymethylmethacrylate (PMMA), which simulates a medium breast. Additionally, simulations with these experiments are increasingly essential. Therefore, the objective of this work was to evaluate the mean glandular dose (DGM), kerma and spectra in PMMA plates, using the following equipment: a mammograph; a solid state detector; a spectrometer (for spectra only); a clinical COMET X-ray tube; and the MCNPX Code. The references recommend, in the DR, the following X-ray tube voltages: 25 kVp; 26 kVp; 28 kVp; 31 kVp and 33 kVp. For the CR system: 26 kVp; 28 kVp; 30 kVp and 32 kVp. Finally, for DBT: 26 kVp, 29 kVp, 30 kVp and 33 kVp. The results involving the DGM in metrological, clinical and simulated cases were in accordance with the references from 30 mm of PMMA, in the DR system; in the CR system, from 28 kVp (Mo/Mo), 30 kVp (Mo/Rh), and 32 kVp (Rh/Rh); in DBT, the results were lower than the references. All spectra of the three cases indicated good agreement with the literature.