Experimental comparison of noise and resolution for 2k and 4k storage phosphor radiography systems

Abstract

The purpose of this study was to compare the image quality for a digital storage phosphor system using 1760×2140 and 3520×4280 image arrays. Measurements were made on a chest radiography system (Fuji FCR-9501) with special provisions to be operated in both (standard) and (HQ) modes. Presampled modulation transfer functions (MTF) were measured using an edge method. Noise power spectra (NPS) were determined for different input exposures by two-dimensional Fourier analysis. These measures along with exposure measurements and an x-ray spectral model were used to determine the frequency-dependent detective quantum efficiency DQE (f ) of the system for the and the modes. The magnitude of the NPS for the mode was about 1/2 that of the mode. A MTF value of 0.5 was found at 1.25 cycles/mm for the system and 1.50 cycles/mm for the system. The images had an extended MTF of 0.1 at 4.5 cycles/mm in the plate-scan direction. Overall, the DQE (f ) of the mode was slightly better than that for the mode by about 0.02 due primarily to its better noise characteristics.