Quality of images acquired with and without grid in digital mammography.

In this study, we assessed the quality of digital mammography images acquired with a grid and without a grid for different kVp values. A digital mammography system was used for acquisition of images of the CIRS Model 015 Mammography Accreditation Phantom. The images were obtained in the presence of the grid and then with the grid removed from the system. The energy of the X-rays was varied between 26 and 32 kVp. The images were evaluated by five senior radiologic technologists with extensive experience in mammography. Statistical analysis was carried out with the Mann-Whitney non-parametric test with the level of significance set at p = 0.05. The comparison between images obtained with a grid and without a grid indicated that, for the visibility of fibers, the non-grid images at 28 kVp were significantly (p = 0.032) better than the images acquired with a grid. At all other kVp values, the images were not statistically different regarding the visibility of fibers. For the visibility of specks and masses, the images did not show any significant differences at any of the kVp values of the study. Imaging with kVp higher than 30 requires a grid to improve the visibility of fibrous calcifications and specks. For the visibility of masses at 32 kVp, no statistically significant differences between the grid and non-grid images were found.