On the effect of FineView,mean energy and anti-scatter grid on the DQE of a mammography system

The GE Senographe DS digital mammography system includes a preprocessing algorithm called FineView designed to improve spatial resolution. The effect of FineView on modulation transfer function MTF, normalized noise power spectrum NNPS, and detective quantum efficiency DQE has been measured by some authors under different experimental conditions and their results do not always agree. We have evaluated the effect of FineView on these functions under rigorous standard conditions, following the 2007 IEC guidelines for DQE measurement in digital mammography detectors. We have also investigated the impact on DQE of the use of different beam spectra and the presence of the anti-scatter grid. Measurements were made with Mo/Mo, 28 kV operating voltage, and 2 mm Al at tube exit. MTF was obtained with the edge method, detector air-kerma DAK levels ranged from 60 to 272 μGy, and the grid was set in or out, depending on the measurement. DQE values showed a dependence on DAK but were not significantly affected by FineView. The effect of the grid on DQE was of the order of 2% average difference and considered nonsignificant, while no effect of beam quality on DQE was observed at 200 μGy, and 6% average difference was observed between 18.5 and 19.4 keV mean energies at 60 μGy, also considered nonsignificant.