Optimization of Image Quality in Digital Mammography with the Response of a Selenium Detector by Monte Carlo Simulation

Mammography machines must meet high requirements to ensure the quality of the generated images. On the other hand, due to the use of ionizing radiation, there is a need to minimize the dose received by patients. To optimize both of these parameters (dose and image quality), the response characteristics of image detectors and, depending on the composition of the breasts, the physical contrast of the examined structures should be considered. This study aimed to determine the optimal voltage values for a given breast thickness during imaging with the use of a selenium image detector. Analysis was carried out using the Monte Carlo simulation method with the GEANT4 code. Our results reveal that the combination of Mo anode together with Mo filtration (the system recommended in analog mammography) was the least favorable combination among those used in digital mammography machines with a selenium detector. Moreover, the use of Rh filtration instead of Mo was advantageous regardless of the thickness of the breast and resulted in a significant improvement in image quality with the same dose absorbed in the breast. The most advantageous solution was found to be an X-ray tube with a W anode. The highest values of the image quality-to-dose ratio were observed for breasts with dimensions ranging from 53 mm to 60 mm in thickness. Lower image quality was observed for breasts with smaller dimensions due to high breast glandularity, resulting in the deterioration of the physical contrast.