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

Michael J. Flynn, Ehsan Samei, and David A. Reimann

82st Scientific Assembly and Annual Meeting of the Radiologic Society of North America. Chicago, Illinois, 1-6 December 1996. Accpted for Presentation, Paper 1082.

PURPOSE: To compare the image quality for a digital storage phosphor system using either 1760 x 2140 (2K) or 3520 x 4280 (4K) arrays.

MATERIALS AND METHODS: Measurements were made on a chest system (Fuji FCR-9501) with special provisions for 2K or 4K (HQ) modes. Presampled MTF was measured using both edge and slit phantoms. NPS was determined for different input exposures by 2D Fourier analysis. DQE was estimated using exposure measurements.

RESULTS: NPS from the 4K system was 1/2 that of the 2K system. The .5 MTF value was at 1.25 for the 4K system and 1.50 for the 2K system. The 4K images had an extended vertical MTF with .1 at 4.5 cycles/mm. Overall, the DQE of the 4K system was slightly better system due primarily to it's better NPS.

CONCLUSION: The Fuji FCR-9501HQ (4K) has less noise with similar resolution than the FCR-9501 (2K). Resolution is probably limited by the opto-physical properties of the ST-V screens employed.

Disclosure: Support from Fuji is acknowledged.

TAKE HOME POINTS: For the Fuji FCR-9501, the HQ option with .1 mm pixels improves noise relative to systems with .2 mm pixels. This improvement is still present when the 4K images are reduced to 2K.

Copyright © 1996, David A. Reimann. All rights reserved.